Class 7

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 16 Natural Resources Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 16 Natural Resources

Class 7 Science Chapter 16 Natural Resources Textbook Questions and Answers

1. Describe natural resources with reference to the following 3 types:

Question a.
Mineral resources
Answer:
Mineral wealth has an important place among natural resources. The rocks on the earth are mainly made of minerals. These minerals can be obtained by mining. Minerals that contain a high proportion of metals are ores, (i) Minerals are formed from the magma in the earth’s crust and the lava from the eruption of volcanoes when they cool and get transformed into crystals e.g. magnetite, mica, (ii) Minerals get transformed from one form into another due to large changes in temperature and pressure e.g. Diamond, Graphite, (iii) There are 3 types of minerals according to their properties Non-metal minerals: e.g. mica, sulphur, potash, diamond.

• Metals minerals: e.g. Iron, gold, silver, tin, bauxite, platinum.
• Energy minerals: e.g. Coal, mineral oil, natural gas, diamond, ruby, sapphire, jade are used as gems.

Some important minerals and ores are Iron ore, manganese, bauxite, copper and mica.

Question b.
Forest resources
Answer:

1. A forest is a natural habitat of plants, animals and microbes.
2. Forest perform certain specific protective and productive functions.
3. We get different types of wood and many medicinal plants from forests.
4. Forest wealth includes fire wood, trees like teak, mahogany, neem, acacia, subabhul, fibers, paper, rubber, gum, aromatic substances.
5. We get fragrant essential oils from lemon grass, vanilla, kewada, vetiver (khus) and eucalyptus.
6. Sandalwood and oil of eucalyptus are used for making soaps, cosmetics and incense sticks.
7. Also we get fruits, bulbs, roots, honey, sealing wax, dyes from forest.
8. Many medicinal plants adulsa, bel, neem, periwinkle, cinnamon, are used for treatment of various diseases such as cough cold, malaria, diarrhoea, cancer, fever and cold.
9. Wood is used as a source of energy for cooking purpose and for keeping warm.
10. For making furniture, tool handles, matches, bridges, boats etc.
11. Bamboos are used for matting, flooring, basket, ropes, rafts, cots etc.
12. Bamboos, wood are used in the manufacture of rayon, yams, artificial silk-fibers.

Question c.
Ocean resources
Answer:

1. Oceans occupy about 70% of a earth’s surface.
2. Energy can be obtained on a large scale from oceans.
3. Sea waves at high and low tide and ocean currents are being used for generation of power.
4. There are billions of tons of minerals dissolved in ocean water.
5. There are large reserves of tin, chromium, potassium, phosphates, copper, zinc, iron, lead, thorium, manganese, sulphur, uranium in the ocean and sea beds.
6. Also we get many types of gems, conches, shells and pearls from the sea.
7. There are large reserves of mineral oil and natural gas at the bottom of sea.
8. We get fishes, dried shrimp, shells, fungi, shark, cod fish and sea cucumber from the ocean.

2. Write answers to the following questions in your own words.

Question a.
What is meant by fossil fuel? What are their types?
Answer:

1. Fossil fuels (such as coal or natural gas) are formed in the earth from dead plants and animals, due to high pressure from above and the heat from the earth’s interior.
2. The dead plants, animals get transformed into fossil fuel.
3. There are three types of fossil fuels which can be used for energy production, Coal, oil and natural gas.

a. Coal:

1. Coal is a solid fossil fuel formed over millions of years by the decay of land vegetation,
2. Coal is a store house of carbon. Coal is found in mines,
3. It is like porous, hard, black rock.
4. It is burnt to obtain heat energy.
5. It is used as a fuel in thermal power plants and to run boilers and railway engines, for cooking and baking bricks.
6. Anthracite is the coal of the highest grade.
7. Producer gas and water gas are obtained from coal.

b. Mineral oil:

1. Mineral oil is the liquid fuel formed by the decomposition of organic substances buried underground,
2. The underground mineral oil is extracted through oil wells.
3. Mineral oil is found mainly in oil sands, shale, sandstone and limestone at a depth of about 1000 to 3000 metres.
4. Mineral oil is also known as petroleum or crude oil. It is greenish-brown in colour.
5. Petroleum is a mixture of many compounds mainly of the hydrocarbon type.
6. It also contains compounds of oxygen, nitrogen and sulphur.
7. Petroleum is extracted through oil wells and refined by fractional distillation to separate other components,
8. Aviation petrol, gasoline, diesel, kerosene, naphtha, lubricating oil, tar are all obtained from petroleum.
9. They are used as fuel and for production of dyes, pesticides, perfumes and artificial fibres.

c. Natural gas:

1. Natural gas is an important fossil fuel.
2. It is lighter than air. It is found with petroleum in underground oil wells and in some places as natural gas alone.
3. The main component of natural gas is methane (CH₄), ethane (C₂H₆), propane (C₃H₈) and butane (C₄H₁₀) are present in small proportions.
4. This gas is highly flammable.
5. This fuel can be carried over long distance by means of a gas pipeline.
6. In absence of pipeline, it is transformed under high pressure into compressed natural gas (CNG) and liquefied natural gas (LNG).

Question b.
Make a list of the components we obtain from mineral oil.
Answer:

1. Mineral oil is the liquid fuel. It is also known as petroleum or crude oil. Petroleum is refined by fractional distillation to separate other components.
2. Aviation petrol, gasoline, diesel, kerosene, naphtha, lubricating oil, tar are the components we obtain from mineral oil.

Question c.
What do we get from forest?
Answer:

1. A forest is a natural habitat of plants, animals and microbes. We get wood, firewood from trees like teak, mahogany, neem, subabhul.
2. Also we get fibers, paper, rubber, gum and aromatic substances.
3. We get many medicinal plants like Adulsa, Bel, Neem, Periwinkle, Cinnamon, Cinchona which are used for treatment of various diseases like cough, cold, diarrhea, fever, cancer, diarrhoea, nausea, malaria.
4. We get fragrant essential oils from lemon grass, vanilla, kewada, khus, eucalyptus.
5. In addition to this we get fruits, bulbs and roots, honey, sealing wax, catechu, dyes from forest.

Question d.
What are the items included in ocean resources? What are their uses?
Answer:

1. Tons of minerals are found in ocean water.
2. They are tin, chromium, phosphates, copper, zinc, iron, lead, manganese, sulphur, uranium etc.
3. We also get many types of gems, conches, shells and pearls from the sea.
4. Mineral oil and natural gas is found at the bottom of sea.

Bio-resources in oceans

• Fishes – like pomfret, seer fish as also shrimps
• prawns – they are sources of proteins and vitamins, therefore, mainly used as sea food
• Dried shrimp, Bombay duck powder – used as poultry feed and is a good manure.
• Shells – used for preparation of medicines, ornaments and decorative articles.
• Fungi – used for the production of antibiotics.
• shark and cod fish – used for producing edible oil rich in Vitamins A, D and E.
• Sea cucumbers – used as medicine for treating cancer and tumours.

Mineral resources from oceans

• Thorium – used in the production of atomic energy.
• Magnesium – used in the flash bulb of a camera.
• Potassium – the main ingredient in production of soap, glass, fertilizer.
• Sodium – used in the production of cloth and paper.
• Sulphate – used in making artificial silk.

Question e.
Why should we prevent the wastage of fuels used for vehicles?
Answer:

1. Vehicles are powered by gasoline or diesel petrol.
2. Nowadays compressed natural gas (CNG) is also used.
3. Aviation petrol, gasoline, diesel, we get from petroleum after fractional distillation.
4. Petroleum is a non-renewable source of energy.
5. It is getting depleted day by day and the demand for fuel has increased greatly due to the rapidly growing population.
6. But the reserves of petroleum (fossil fuel) are limited.
7. It is becoming difficult to meet the increased demand. So we should prevent the wastage of fuel.

Question f.
Why is the diversity of plants and animals in the forests declining?
Answer:

1. The major causes of biodiversity decline are land use changes, pollution, changes in atmosphere, CO₂ concentration, changes in the nitrogen cycle, acid rain, climate alteration and introduction of exotic species.
2. All this is due to population growth.
3. This is the main cause of the loss of biodiversity. More of wood for fuel is been used, more land is required for food production, livestock grazing etc.
4. Rainforest land is converted to industrial and residential usage, so natural habitat of birds, animals is destroyed.
5. Due to population growth most of wild land is converted to crop land. So no space for animals to live, their natural habitat is destroyed.

Question g.
Write the names of five minerals and the useful substances obtained from them.
Answer:
Some important minerals and ores are:

1. Iron ore: It is used for making farming implements, rails of railway tracks etc.
2. Manganese: Compounds of manganese are used in the preparation of medicines and for giving a pink tinge to glass. Manganese is also used in electrical appliances.
3. Bauxite: It contains 55% Aluminium. Therefore, it is used mainly in aeroplanes, transport vehicles and to make electric wire.
4. Copper: It is used to make electric wires as well as in radios, telephones, vehicles, and for making kitchen utensils and statues.
5. Mica: Mica has many uses such as in ayurvedic medicines, dyes, electric machines and equipment, wireless communication equipment, etc.

Question h.
Name the two important stages in the process of obtaining metals from ores.
Answer:
The two important stages in the process of obtaining metals from ores are extraction and purification.

3. What steps are taken for protection and conservation of natural resources?

Question a
What steps are taken for protection and conservation of natural resources?
Answer:

1. Protection and conservation of natural resources is necessary to protect the natural world. (CNRM) Community Natural Resource Management has been promoted in recent years for biological conservation.
2. The World Conservation Union has been formed. It is the world’s leading authority and democratic platform in conservation and sustainability.
3. Young trees should not be cut. More and more trees need to be grown.
4. The stringent restrictions/ laws/ Regulations regarding use of forests should be strictly followed. Awareness is being created through Mass media.

4. Complete the Flow Chart:

Question a.

Answer:

5. How does the economic condition of a nation depend on its natural resources?

Question a.
How does the economic condition of a nation depend on its natural resources?
Answer:
1. Natural resources are a necessary condition for economic growth.
2. Three circles enclosed within one another shows how both economy and society are subsets of our planetary ecological system.

3. Natural resource economics deals with the supply, demand and allocation of the Earth’s natural resources.
4. Economic growth is an increase in the value of goods and services produced in an economy.
5. The natural resources of a country depend on the climatic and environmental conditions.
6. Countries having plenty of natural resources enjoy good growth than countries with small amount of natural resources.
7. A country having skilled and educated work force with rich natural resources takes the economy on the growth path, because skilled and educated people can efficiently utilize or exploit natural resources, e.g. Saudi Arabia: their economic growth is high, because they have oil wells.
8. All countries import fuel or oil from them so Saudi Arabia is economically a rich country.

6. Which medicinal plants will you grow on your school premises and near your house? Why?

Question a.
Which medicinal plants will you grow on your school premises and near your house? Why?
Answer:
1. I will grow tulsi, neem, lemon grass, bel, adulsa, periwinkle, cinnamon, ashwagandha, shatavari, amla, hirda, behda.
2. These plants are used for treatment of various diseases.

• Tulsi → for cough and cold.
• Amla, hirda, behda → Help in digestion of food or any stomach related problems.
• Adulsa → for cough and cold
• Bel → for Diarrhoea
• Neem → Fever and cold
• Periwinkle → Cancer
• Cinnamon → Diarrhoea, nausea.
• Cinchona → Malaria.
• Ashwagandha → It can reduce blood sugar levels. It can reduce stress and anxiety, may reduce symptom of depression.
• Shatavari → has been used for centuries in Ayurveda to support the reproductive system.
• Amla → Excellent source of vitamin C. Amla juice is best tonic to keep you younger for long.
• Hirda → This fruit is commonly called Haritaki. It is used for treating arthritis, dental problems like caries, bleeding gums.
• Behda →(Beleric) is a rejuvenative and laxative, proves beneficial for hair, throat and eyes.
• Tulsi → Tulsi has germicidal, fungicidal, anti-bacterial anti-biotic properties, cures fever. Treats diabetes, protects the heart. Tulsi has anti-oxidant component Eugenol which keeps one’s blood pressure under control.

Project:

Question 1.
Collect conches and shells of various shapes and colours and make a decorative article.

Question 2.
Collect information about the mines of various minerals.

Class 7 Science Chapter 16 Natural Resources Important Questions and Answers

Fill in the blanks:

Question 1.
………….. is the major raw material for biogas.
Answer:
cow dung

Question 2.
Atomic energy is obtained by using ores of ………….. .
Answer:
Uranium

Question 3.
Biogas generation is mainly based on the principle of ………….. .
Answer:
Fermentation

Question 4.
Floods can be prevented by ………….. .
Answer:
Afforestation

Question 5.
Coal, petroleum, natural gas are ………….. resources.
Answer:
non-renewable

Question 6.
The total percent of land of world under forest cover is ………….. .
Answer:
30%

Question 7.
A naturally occurring substance ………….. .
Answer:
minerals

Question 8.
Minerals that contain a high proportion of metal are called ………….. .
Answer:
ore

Question 9.
Coal, mineral oil and natural gas are ………….. .
Answer:
fossil fuel

Question 10.
Deposits of common salt are also found in the earth. This salt is called ………….. .
Answer:
rock salt

Question 11.
………….. is the liquid fuel formed by the decomposition of organic substances.
Answer:
Mineral oil

Question 12.
The underground mineral oil is extracted through ………….. .
Answer:
oil wells

Question 13.
Mineral oil is also known as ………….. or ………….. .
Answer:
petroleum, crude oil

Question 14.
………….. are the preserved remains of dead organisms in rock.
Answer:
Fossil

Question 15.
Coal can be formed from ………….. .
Answer:
Fossils

Question 16.
Impurities of sand and soil in ore are called ………….. .
Answer:
Gangue

Question 17.
Coal mainly contains ………….. .
Answer:
carbon

Question 18.
Petroleum is formed from ………….. .
Answer:
organisms in sea

Question 19.
Separation of various fractions of petroleum is called ………….. .
Answer:
Refining

Question 20.
We can obtain minerals from rocks by ………….. .
Answer:
mining

Question 21.
………….. is the most important ore of aluminium
Answer:
Bauxite

Question 22.
………….. is the coal of the highest grade.
Answer:
Anthracite

Question 23.
Metals are obtained from their ore by ………….. and ………….. .
Answer:
extraction, purification

Question 24.
………….. is the largest oil and gas research and production company in India.
Answer:
ONGC

Question 25.
Natural gas is transformed under high pressure into ………….. and ………….. .
Answer:
LNG and CNG

Question 26.
The main component of Natural gas is ………….. .
Answer:
Methane

Question 27.
………….. and ………….. are used for adding fragrance in soaps and incense sticks.
Answer:
Sandalwood and oil of Encalyptus

Question 28.
………….. is a natural herbal medicine for cough and cold.
Answer:
Adulsa

Answer the following:

Question 1.
What is meant by natural resources?
Answer:

1. We get many substances from nature.
2. They satisfy a variety of our daily needs. Soil, stones, minerals, air, water, plants and animals on the earth are all various kinds of natural resources.

Question 2.
What are alternative fuels?
Answer:
Hydrogen, biofuels, methanol or wood alcohol, ethanol or green alcohol are some of the alternative fuels.

Question 3.
What is meant by fuels?
Answer:

1. Fuel is a substance that is used in day-to-day life and burned to generate energy.
2. Fuels such as coal, wood, oil, gas provide energy when burned.
3. Fuels are found in solid, liquid or gaseous state.

Question 4.
Which natural resources do we use as fuels?
Answer:
We use coal, mineral oil and natural gas as fuels.

Question 5.
What is meant by forests?
Answer:
An extensive area of land covered by a variety of plants is called a forest. A forest is a natural habitat of plants, animals and microbes.

Question 6.
What are the uses of forests?
OR
Write short note on forest and its uses.
Answer:

1. A forest is a natural habitat of plants, animals and microbes.
2. Forest help improve and maintain the quality of environment.
3. Forest helps in prevention of soil-erosion, help to control floods, protects wild life, maintains the balance of atmospheric gases.
4. We get many medicinal plants from forest which help in treatment of various diseases.
5. Examples Adulsa, Bel, Neem, periwinkle, amla tulsi, cinnamon.
6. We also get wood, firewood from trees like teak, mahogani, neem, sababhul. Wood is useful for making furniture, farming implements, in construction work.
7. Forest wealth includes fibres, paper, rubber, gum and aromatic substances.
8. We get fragrant essential oils from lemon grass, vanilla, kewada and eucalyptus.
9. They are used for making soaps, cosmetics and incense sticks. We get various fruits, bulbs, roots, honey, sealing wax, catechu dyes etc. from forest.

Question 7.
Are minerals to be found in seas and on the seabed as they are found inside the earth?
Answer:
Yes, there are very large reserves of tin chromium, phosphates, copper, zinc, iron, lead, manganese, sulphur, uranium etc. in the ocean and seabed.

Question 8.
How is mineral oil formed?
Answer:

1. Mineral oil is the liquid fuel formed by the decomposition of organic substances buried underground.
2. Millions of years ago, bodies of dead sea organisms sank to the bottom of the sea.
3. Layers of soil and sand collected on them.
4. Due to high pressure and temperature the remains of the dead organisms were transformed into mineral oil.
5. The underground mineral oil is extracted through oil wells.

Use your brain power!

Question 1.
Why are all minerals not ores?
Answer:

1. Minerals that contain a high proportion of metal are called ores.
2. Majority of the metals occur in the form of compounds called ores.
3. But all minerals are not ores.
4. Few metals like gold, silver, copper, platinum and bismuth occur in free state in nature. So all minerals are not ores.

Question 2.
What is meant by metal mineral and non¬metal mineral?
Answer:

1. Metal-minerals contain metallic elements in their chemical formula. So they are called metal-minerals, for example, iron, copper, gold, silver etc.
2. They contain metal in raw form.
3. Non-metallic minerals do not contain metal elements in their inorganic chemical formula Example, Clay, Diamond, Dolomite, Gypsum, Mica, Quartz.

Question 3.
Why is mineral oil called ‘liquid gold’?
Answer:
Because of its high price and value and its economic need, the mineral oil is called liquid gold. It’s reserve is less and demand is more.

Question 4.
Why is coal called black gold?
Answer:

1. Coal is a storehouse of carbon. Coal is used as a fuel, in thermal power plants as well as to run boilers and railway engines.
2. It is used as a fuel for cooking and for baking bricks in kilns on a large scale.
3. The gaseous fuels, producer gas and water gas are obtained from coal.
4. Coal as an energy resource, contributes greatly to industrial development.
5. As coal is black in colour and worth a lot of money just like gold, it is called black gold.

Question 5.
What would happen if underground mineral resources are exhausted?
Answer:

1. Coal, petroleum and other mineral are all non-renewable sources of energy.
2. The reserve is less and demand is more. They would get exhausted one day.
3. If such a situation occurs, we will not get electricity.
4. All our household and industries depend on electricity.
5. Transportation and household items, and food items would become very costly.
6. The survival of human life will be ver\ difficult.

Question 6.
Why is natural gas an eco-friendly fuel?
Answer:

1. Natural gas is an important source of energy which is eco-friendly because of its low carbon dioxide emission.
2. When burned it produces 45% less CO₂ than coal, 30% less than oil, and about 15% less than wood.
3. It does not produce carbon monoxide, sulphur dioxide or airborne particles, all of which are harmful to human and animal health.
4. It is referred as the clean energy source and is fuel for the present century as it does not ‘ pollute the atmosphere or contribute to global warming.

Question 7.
What useful things will we have to do without if rubber is no longer available?
Answer:

1. Rubber has played a largely hidden role in global environment history for more than 150 years.
2. In industries, rubber is needed to connect and protect all moving parts of machines.
3. Native people used rubber for rubber boots.
4. Household uses rubber in everything viz dish washing gloves, toys, jar seals, tyres in vehicles.
5. Welcome mat at the door, Boots, raincoats, mattress cushions, earplugs, hot water bottles, surgical tubing and gloves, in labs, birth control device.
6. In schools rubber bands, erasers, mouse pads, key board, rolling chair wheels. Head phone pads, rubber stamps are useful items used in schools and offices.

Question 8.
What are the adverse effects of clearing of forest or cutting down trees?
Answer:

1. Clearing of forest is also called Deforestation.
2. Removal or cutting down of trees has resulted in damage to habitat, biodiversity loss and aridity.
3. If has adverse impacts on concentration of atmospheric carbon dioxide. (Trees use up carbon dioxide from the atmosphere for the process of photosynthesis.)
4. Deforestation is a main contributor to global warming. Major cause of enhanced greenhouse effect. Deforestation cause carbon dioxide to linger in the atmosphere.
5. Deforestation reduced the content of water in the soil and ground water and atmospheric moisture, because trees extract ground water through the roots and release it into the atmosphere.
6. When a part of forest is removed the trees no longer transpire this water, resulting in much drier climate.
7. Due to deforestation soil erosion and flooding, landslide problems occur.
8. Deforestation results in decline in biodiversity, on a natural global scale is known to cause the extinction of many species.
9. Forest is habitat for wild life, and many medicinal plants. If forests are removed it will affect wild life and also we will not get medicinal plants.

Find out:

Question 1.
How did the various ages of the prehistoric period get their names on the basis of the uses of metals.
Answer:
1. The three-age system in history archaeology, and physical anthropology is a methodological concept adopted during the 19th century by which artifacts and events of late prehistory and early history could be ordered into a recognizable chronology.

2. Initially developed by C. J. Thomson, director of the Royal Museum of Nordic Antiquities, Copenhagen – as a means to classify the museum’s collection according to whether the artifacts were made of stone, bronze or iron.

3. Depending-upon the use of stone, bronze, iron, that period was known as stone age, bronze age, and iron age, respectively.

Answer the following:

Question 1.
Write down the difference between Metal minerals and Non-metallic minerals.
Answer:

Metal minerals	Non-metallic minerals
1. Metal minerals contain metal in raw form.	1. Non-metallic minerals do not contain metal.
2. These metals are generally associated with igenous rocks.	2. These metals are generally associated with sedimentary rocks.
3. They are usually hard and have shine of their own.	3. They are not usually hard, have no shine of their own.
4. e.g. Iron, copper tine, bauxite.	4. e.g. Salt, coal, mica, clay.

Question 2.
Write down the different types of coal.
Answer:
Peat, lignite (brown coal), bituminous coal and anthracite are various types of coal.
Anthracite is the coal of the highest grade.

Question 3.
Write down the characteristics of Compressed Natural Gas.
Answer:
Characteristics of CNG:

1. Catches fire easily.
2. No solid waste remains after combustion.
3. Carbon dioxide and water are formed in small quantities.
4. Other pollutants are not produced.
5. Can be transported easily.
6. Combustion can be controlled easily.

Observe the pictures and answer the question.

Question a.
What is the process shown in the given picture?
Answer:
The process shown is formation of mineral oil and natural gas.

Question b.
Explain the process.
Answer:

1. Mineral oil is the liquid fuel formed by the decomposition of organic substances buried underground.
2. Millions of years ago, bodies of dead sea organisms sank to the bottom of the sea.
3. Layers of soil and sand collected on them.
4. Due to high pressure and temperature the remains of the dead organisms were transformed into mineral oil.
5. The underground mineral oil is extracted through oil wells.

Question c.
What are the gaseous substances formed in the above process?
Answer:
Natural gas is also formed along with mineral oil. It contains methane, ethane, propane and butane gases.

Question d.
When the products of the process is refined, what other components are produced?
Answer:
When mineral oil is refined by fractional distillation products produced are petrol, diesel, kerosene, naphtha lubricating oil, tar, etc.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 20 In the World of Stars Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 20 In the World of Stars

Class 7 Science Chapter 20 In the World of Stars Textbook Questions and Answers

1. Write the proper words in the blanks:
(meridian, horizon, twelve, nine, apparent, celestial, ecliptic)

Question a.
When seen from a great distance, the sky seems to be touching the ground along a circle. This circle is called the …………… .
Answer:
horizon

Question b.
The ………….. is used while defining the zodiac sign.
Answer:
meridian

Question c.
Classified according to seasons, one season will have ………… nakshatras.
Answer:
nine

Question d.
The rising of the sun in the east and its setting in the west is the ………. motion of the sun.
Answer:
apparent

2. A star rises at 8 pm. tonight. At what time will it rise after a month? Why?

Question a.
A star rises at 8 pm. tonight. At what time will it rise after a month? Why?
Answer:

1. Str s rise and set 4 minutes earlier every day. If star rises at 8 pm tonight, it will rise at 7:56 pm tomorrow.
2. It will rise at 5:24 pm after a month.
3. The sun and the moon are seen to move from the west to the east against the background of stars.
4. The sun moves through one degree every day and the moon through 12 to 13 degrees.
5. This happens due to the motion of the earth around the sun and the moon around the earth which affects the duration of the stars and shortens its time period.

3. What is meant by “The sun enters a nakshatra?” It is said that in the rainy season the sun enters the mrug nakshatra. What does it mean?

Question a.
What is meant by “The sun enters a nakshatra?” It is said that in the rainy season the sun enters the mrug nakshatra. What does it mean?
Answer:

1. When we look at the sun we see not only the sun but also constellation behind the sun.
2. The constellation cannot be seen in bright sunlight but it is indeed present behind the sun.
3. As the earth changes its position, a different constellation or zodiac sign or raashi appears behind the sun.
4. This is what we express when we say that the sun enters a particular zodiac sign or raashi.
5. In rainy season due to the perceived motion of the sun, it enters mrug nakshatra and that is how it is expressed.

4. Answer the following questions. 

Question a.
What is a constellation?
Answer:
A group of stars occupying a small portion of the celestial sphere is called a constellation.

Question b.
What points should be considered before a skywatch?
Answer:

1. The place for sky watching should be away from the city and as far as possible it should be new moon night.
2. Binoculars or telescopes should be used for skywatch.
3. Identifying the pole star in the north makes the skywatch easier. Hence the pole star should be used as a reference point for skywatch.
4. As the stars in the west set early, sky watching should begin with stars in the west.
5. (a) On a sky map, the north and south are towards the bottom and top of the map respectively, (b) This is because the sky map is to be held overhead in such a way that the direction we face is at the bottom side.

Question c.
It is wrong to say that the planets, stars and nakshatras affect human life. Why?
Answer:

1. Science has proved that the constituents of the solar system e.g. planets, satellites and comets as also distant stars and constellations do not have any influence on human life.
2. Man has stepped on the moon and will conquer Mars in the 21st century.
3. Hence, in this age of science, holding on to beliefs which have been proved wrong by numerous scientific tests, is an unnecessary waste of time and energy.
4. It is important to consider all these issues with a scientific frame of mind.

5. Write a paragraph on the birth and life cycle of stars using following figure.

Question a.
Write a paragraph on the birth and life cycle of stars using following figure.
Answer:
Stars are born out of nebulae. Nebulae are clouds made up mainly of hydrogen gas and dust particles which are attracted towards one another by the force of gravity, (i) As a result of pressure, the internal temperature increases and the cloud becomes dense and spherical in shape, (ii) From the diagram, life cycle of two stars can be explained.

(a) Ordinary star: (i) The ordinary star forms a Red giant star at the later stage of its evolution when it runs out of hydrogen gas at its core. (ii) At the end stage of its life it forms a white dwarf. Stars like the sun become white dwarf when its nuclear fuel is totally exhausted. (iii) It is 1% in diameter of its original size.

(b) Massive Star: (i) Massive star forms Red super giant star at the end of its life cycle, (ii) They are also called super red giants with a relatively cool outer surface, (iii) Supernova is the explosive death of the star of the end of its life with the brightness of 100 million stars in a short amount of time, (iv) A neutron star is the dense core of the supernova. (v) It is the smallest and the densest star known to exist with a 10 km radius, (vi) Neutron stars sometimes end as a black hole, (vii) Black holes are not seen from telescopes and are identified by their intense gravitational pull where even light cannot escape.

Project:

Question a.
Visit a planetarium, collect information and present it in your school on Science day.

Class 7 Science Chapter 20 In the World of Stars Important Questions and Answers

Fill in the blanks:

Question 1.
The different group of stars is known as ………….. .
Answer:
constellation

Question 2.
The pole star is ………….. .
Answer:
North star

Question 3.
The moon moves around the earth in about ………….. days.
Answer:
27 days

Question 4.
The celestial objects are ………….. .
Answer:
The stars

Question 5.
The star that lies close to the aris of rotation of the earth ………….. .
Answer:
Pole star

Question 6.
The definite elliptical path in which a planet revolves around the sun is called ………….. .
Answer:
Orbit

Question 7.
Our earth as well as the sun belongs to the galaxy which has a spiral shape called ………….. .
Answer:
milky way

Question 8.
………….. is made up of five bright stars which are distributed along the figure of the letter M.
Answer:
Sharmishtha

Question 9.
The pole star has ……………. on one-side and ……………… on the other.
Answer:
Saptarashi, Sharmishtha

Question 10.
The continuous empty space between the planets and stars in the sky is called ………….. .
Answer:
space

Name the following:

Question 1.
The brightest star in the nakshatra.
Answer:
Yogatara

Question 2.
The stars forming a group that has a recognizable shape.
Answer:
Constellation

Question 3.
Millions of stars and planets present in the sky forming a group.
Answer:
Milky way

Question 4.
The clouds from which stars are bom.
Answer:
Nebulae

Question 5.
Saptarshi constellation in English.
Answer:
Great Bear

Question 6.
The festival celebrated when sun enters Makar raashi.
Answer:
Makara Sankranti

Question 7.
The brightest star in the Orion constellation.
Answer:
Sirius

State whether the following statements are True or False. Correct the false statements:

Question 1.
The hydrogen gas and dust particles in a nebulae are attracted towards each other by gravity.
Answer:
True

Question 2.
While standing on the ground, the celestial sphere exactly below our feet is called the Zenith.
Answer:
False. The point on the celestial sphere exactly above our head is called the Zenith

Question 3.
The circle describing the apparent motion of the earth around the sun is called the ecliptic.
Answer:
False. Ecliptic is the apparent motion of sun around the earth

Question 4.
Vrushchik or Scorpio is a constellation with 10 to 12 stars.
Answer:
True

Question 5.
Makar raashi is also known as Capricorn zodiac sign.
Answer:
True

Match the following:

Question a.

Column ‘A’	Column ‘B’
1. Saptarshi	a. Divided into 88 constellations
2. Mmg nakshatra.	b. In the north direction.
3. Orion	c. Group of 7 bright stars (kite)
4. Vrushchik	d. Made up of 5 bright stars (M)
5. Pole star	e. 7 – 8 stars.
6. Celestial sphere	f. Group of 10 -12 stars

Answer:

Column ‘A’	Column ‘B’
1. Saptarshi	c. Group of 7 bright stars (kite)
2. Mmg nakshatra.	d. Made up of 5 bright stars (M)
3. Orion	e. 7 – 8 stars.
4. Vrushchik	a. Divided into 88 constellations
5. Pole star	b. In the north direction.
6. Celestial sphere	f. Group of 10 -12 stars

Answer in one line:

Question 1.
In which direction stars move in the sky except polar star?
Answer:
When seen from earth, stars appear to move from east to west.

Question 2.
What activity does IUCAA carry out?
Answer:
IUCAA which is present in PUNE carries out fundamental research in astronomy.

Question 3.
Define constellation.
Answer: A group of stars occupying a small portion of the celestial sphere is called constellation.

Question 4.
What is Nakshatra?
Answer:
The moon completes one revolution around the earth in approximately 27 days. The portion celestial sphere traversed by the moon in one day is called a nakshatra.

Question 5.
What is yogatara?
Answer:
A nakshatra is known from the brightest star that it contains. The brightest star is called the yogatara.

Define the following:

Question 1.
Horizon
Answer:
Far away the sky seems to be touching the ground. The line at which they meet is caled horizon.

Question 2.
Zenith
Answer:
While standing on the ground the point on the celestial sphere exactly above our head is called the Zenith.

Question 3.
Nadir
Answer:
While standing on the ground the point on the celestial sphere exactly below our feet is called the nadir.

Question 4.
Meridian
Answer:
The great circle which passes through both the celestial poles and the observer’s zenith and nadir is called a meridian.

Question 5.
Celestial equator
Answer:
If we uniformly expand earth’s equator in all directions indefinitely, it will penetrate the celestial sphere along a circle. This circle is known as the celestial equator.

Question 6.
Ecliptic
Answer:
The earth moves around the sun, but seen from the earth, the sun appears to move along a circle on the celestial sphere. This circle describing the apparent motion of the sun around the ‘ earth is called the ecliptic.

Question 7.
Zodiac sign
Answer:
The ecliptic has been imagined to divided into 12 equal parts. Each part subtends 30 degrees at the centre of the celestial sphere. Each of these part is called a raashi or zodiac sign.

Question 8.
Mrug Nakshatra or Orion
Answer:
It has 7 – 8 starts of which four are at the comers of quadrangle. The line passing through the three middle stars of the constellation when extended meets a very bright star. This is Vyadh or Sirius.

Find out.

Answer the following questions

Question 1.
Using a Marathi calendar collect information about 27 nakshatras, and divide them into the following 3 categories.
(i) Monsoon Nakshatra (ii) Winter Nakshatra (iii) Summer Nakshatra
Answer:
27 nakshtras: Ashwini, Bharani, Krittika, Rohini, Mrigashirasha, Ardra, Punarvasu, Pushya, Ashlesha, Magha, PurvaPhalguni, Uttara Phalguni, Hasta, Chitra, Swati, Vishakha, Anuradha, Jyeshtha, Mula, Purva Ashadha, Uttara Ashadha, Abhijit, Shravana, Dhanishtha, Shatabhishta, Purva Bhadrapada, Uttara Bhadrapada, Revati

Monsoon Season	Winter Season	Summer Season
Ashwini Karthe	Krittika	Visakha
Bharani Karthe	Rohini	Anuradha
Arudra Karthe	Mrigashirsha	Jyeshtha
Pushyani	Ardra	Mula

Aslesha	Punarvasu	Purva Ashadha
Magha		Uttara Ashadha
Purva Phalguni		Shravana
Uttara Phalguni
Chitra
Hasta

Question 2.
Write the difference between constellations Saptarshi and Mrug nakshatra
Answer:

Saptarshi	Mrug nakshatra
1. It is made up of five bright stars which are distributed along the figure of the letter M.	1. It is made up of seven-eight stars of which four are at the corners of a quadrangle.
2. Pole star is the brightest star in the constellation.	2. Sirius is the brigh jveutr0n Starie constellation.
3. It is on the meridian in the month of April and in the month of October.	3. It is on the meridian in the month of February and in June.
4. In English, it is called the Great Bear.	4. In English, it is called Orion.

Question 3.
Draw sketches to show the relative position of prominent stars in Ursa major and Orion.
Answer:
a. Ursa major (Saptarshi) appears like a big dipper, (or kite shape). There are 3 bright stars in the handle and 4 stars in the bowl of the dipper. (It can be seen during April in summer in northern skies).

(b) Orion appears like a hunter. Three bright stars appear in the belt, 5 bright stars are arranged in the form of a quadrilateral. (It is visible during winter in the northern skies)

Question 4.
Why is the pole star important for sky watch?
Answer:

1. Identifying the Pole Star in the north makes the sky watch easier. Hence the pole star should be used as a reference point for skywatch.
2. If we extend one side of the quadrangle of Saptarshi, it reaches the Pole Star.
   The pole star has Saptarshi on one side and Sharmishtha on the other.

Question 5.
What is the relation between the pole star and the constellations Saptarshi and Sharmishtha?
Answer:

1. Saptarshi is in the shape of a quandrangle with a tail made up 3 stars resembling a kite. If we extend one side of the quadrangle it reaches the Pole Star.
2. The constellations of Saptarshi and Sharmishtha are useful in locating the Pole Star.
3. The perpendicular bisector of the line joining the third and fourth stars in Sharmishtha goes towards the Pole star.
4. The Pole Star has Saptarshi on one side and Sharmishtha on the other.

Use your brain power!

Answer the following questions.

Question 1.
One Zodiac Sign = ………….. nakshatras
Answer:
27 nakshatras. Each nakshatra is divided in padas or charan. Every nakshatra has 4 padas. These 27 nakshatra complete the entire circle of 360° of zodiac.
The zodiac comprises of 360°.

Question 2.
Is sun the only star present in our Milky Way galaxy?
Answer:
No. Sun is not the only star present in the Milky Way. There are lakhs of stars in the Milky Way, some of them being many times bigger than our sun. Some of them have their own planetary systems with a great diversity in colour, brightness, as well as size.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 11 Cell Structure and Micro-organisms Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 11 Cell Structure and Micro-organisms

Class 7 Science Chapter 11 Cell Structure and Micro-organisms Textbook Questions and Answers

1. Answer the following questions.

Question a.
What is a cell?
Answer:
The cell is the fundamental, structural and functional unit of living organism.

Question b.
Name the different organelles in a cell.
Answer:
The nucleus, endoplasmic reticulum, Golgi bodies, lysosomes, mitochondria, vacuoles, plastids, chloroplasts are the different organelles in a cell.

Question c.
What are micro-organisms?
Answer:
The organisms which cannot be seen with our eyes but can only be observed under a microscope are called micro-organisms.

Question d.
Which are the different types of micro-organisms?
Answer:
Algae, fungi, bacteria, protozoa and viruses are various types of micro-organism. Some are unicellular and others are multicellular. Some of them are useful and some are harmful.

2. Fill in the blanks with the proper word.

Question a.
The organelle called the ……………. is present in the plant cells only.
Answer:
chloroplasts

Question b.
Garbage is converted into ……….. by microorganisms.
Answer:
fertilizer

Question c.
In the cell, photosynthesis is carried out with the help of …………… .
Answer:
chloroplast

Question d.
An electron microscope is necessary for the study of ……………… .
Answer:
micro-organism

Question e.
The process of preparing their own food in presence of sunlight and chloroplast by plants cells is known as ……….. .
Answer:
photosynthesis.

3. What is the difference between us?

Question a.
Plant cell and animal cell.
Answer:

Plant cell	Animal cell
1. Plant cell has cell wall.	1. Cell wall is absent in animal cell.
2. Plant cell has definite shape due to presence of cell wall.	2. Animal cell do not have definite shape.
3. Plant cell has one big vacuole.	3. Animal cells have many small vacuoles.
4. Plant cell has chloroplast so they produce their own food.	4. Animal cells do not have chloroplast, so they cannot produce their own food.
5. Plant cell has plastids.	5. Plastids are absent in animal cell.
6. Centrosomes are absent in plant cell.	6. Centrosomes are present near the nucleus.
7. Lysosomes are absent in plant cell.	7. Lysosomes are present in animal cell.

Question b.
Prokaryotic cell and Eukaryotic cell
Answer:

Prokaryotic cell	Eukaryotic cell
1. No well defined nucleus.	1. Well defined nucleus with a nuclear membrane
2. Ribosomes are small.	2. Ribosomes are large.
3. A single length of DNA is present.	3. Several lengths of genetic materials (DNA) is present.
4. No other cell organelles are present.	4. Several organelles like mitochondria, chloroplasts, etc. are present.
5. Examples: Bacteria, blue green algae	5. Examples: Euglena, Amoeba, all plant and animal cells

4. Sketch and describe in your on words, the plant cell and animal cell.

Question a.
Sketch and describe ¡n your on words, the plant cell and animal cell.
Answer:
There are two types of cell-animal cells and plant cells. These cells contain various types of membrane beyond cell-organelles. Plant cells have a definite shape due to the presence of cell wall. Besides, unlike animal cells, plant cells contain single large vacuole. All these cells are known as eukaryotic cells. It cell has four main parts: the cell wall, cell membrane, cytoplasm and cell organelles.
1. Cell wall: The cell wall is the outermost covering of a cell. It is present only in plant cells.

2. Plasma membrane: The plasma membrane, also called the cell membrane, is a kind of thin covering, (a) It is extremely delicate and flexible, (b) It is the outermost covering of animal cells.

3. Cytoplasm: The liquid part in the cell, present around the nucleus is called cytoplasm, (a) It occupies the space between the plasma membrane and nucleus, (b) Cell organelles are scattered in the cytoplasm.

4. Cell organelles: These mainly include the nucleus, endoplasmic reticulum, Golgi bodies, lysosomes, mitochondria, vacuoles, plastids etc.

Plant cells contain chloroplasts.
(a) The nucleus is the most important organelle of the cell, (b) There is a porous double membrane around it. (c) The nucleus controls all functions of the cell, (d) The endoplasmic reticulum is a sprawling net-like organelle. Its function is to make necessary changes in the proteins produced by ribosomes and send them to the Golgi bodies, (e) Golgi bodies are made up of several flat sacs. Their function is the proper distribution of proteins.

(f) Mitochondria and plastids are organelles with double outer coverings, (g) As mitochondria produce energy, they are called the powerhouses of the cell, (h) The chloroplasts in plant cells carry out the function of photosynthesis, (i) Vacuoles help to throw out waste products of the cell, (j) Vacuoles in animal cells are small whereas there is only one large vacuole in a plant cell.

5. Explain the uses and the harmful effects of micro-organisms.

Question a.
Explain the uses and the harmful effects of, micro-organisms.
Answer:
Micro-organisms which are helpful are called useful micro-organisms.
Uses:
1. Micro-organisms present in nodules of leguminous plants, convert atmospheric nitrogen into its compounds and these compounds help to increase the soil fertility and protein content in the soil.

2. Some micro-organisms are useful in process of fermentation, making the food easily digestible and more nutritious. For producing milk products like butter, buttermilk, cheese, paneer, etc.

3. Microbes present in soil, dung etc. decompose garbage and convert into manure of best quality and surrounding is kept clean.

4. Microbes are also useful for sewage disposal. They help in decomposition of organic compounds in it.
5. Microbes are used in production of vaccines.

6. Microbes are also used in processes like tanning of skin, production of ropes and strings, from agave.
7. Some microbes use oil for their growth. Such microbes are used to clear a layer of oil floating on the surface of an ocean or lake formed due to leak or spill.

8. Farm waste, human urine and faeces, wet garbage etc. is collected and used in a biogas plant to produce biogas and fertilizer.

Harmful effects:
1. Disease producing micro-organisms are called pathogens, they are harmful micro-organisms.

2. Fungus grows on moist food, and microbes release enterotoxins into the food. Such toxins spoil the foods. Eating such spoiled food causes food poisoning i.e. loose motions and vomiting.

3. Pathogens may be present in water bodies contaminated with sewage, and dirt from surroundings, in food with flies sitting on it. If such contaminated food or water is consumed, we may fall ill with diseases like amoebiasis, typhoid, cholera, hepatitis, gastro, etc.

4. Pathogens are released in the air by a person having infection of the respiratory, sneezes or coughs. A healthy person may get infected by pathogens on breathing in the same air and contract diseases like common cold, cough, diphtheria, pneumonia, tuberculosis, etc.

5. Microbes that cause diseases like malaria, dengue, elephantiasis, yellow fever, chikunguniya, zike
fever etc. gain entry into the human body through the bite of a female mosquito.

6. Give reasons.

Question a.
Diseases spread on a large scale during periods of heavy rainfall and floods.
Answer:

1. Due to floods there is shortage of clean, safe drinking water.
2. It gets contaminated with sewage and dirt having disease causing pathogens, causing disease of alimentary canal, typhoid, cholera, dysentery.
3. Due to stagnant water, many mosquitoes breed on it and cause diseases like malaria, dengue, etc.

Question b.
There is a possibility of food poisoning if we eat stale food.
Answer:

1. Fungus grows quickly on moist and stale food. Micro-organisms grown on the food release toxic materials like enterotoxin into the food.
2. Such toxins spoil the food.
3. Eating such spoiled food may cause loose motions and vomiting. So, we should eat food which is freshly prepared.

Question c.
Soil is turned over during tilling.
Answer:

1. Tilling is done to loosen the soil in initial agricultural practice.
2. Loose soil allows the penetration of roots of the plant.
3. By turning of soil, it allows uniform mixing of manure and fertilizer.
4. It increases the fertility of soil. Seeds also germinate easily in aerated soil. Hence, soil is turned during tilling.

Question d.
Fungus grows quickly in moist or humid condition.
Answer:

1. Fungus needs water and moisture for its growth.
2. Humidity brings about spore germination and the fungus is able to grow and reproduce quickly in moist or humid condition.

Question e.
A refrigerator is used in almost every home.
Answer:

1. Refrigerator is used to keep food item in healthy condition and to keep them fresh.
2. If the food items are kept outside, they spoil very fast due to growth of micro-organisms and they make food spoiled and harmful.
3. The optimum temperature for the growth of micro-organism is 15°C to 35°C.
4. In refrigerator the temperature is kept very low. So, the food is preserved in refrigerator.

Question f.
Bread rises during baking.
Answer:

1. The process of fermentation is used in baking, for example, in making bread. Yeast is added to make the dough rise.
2. The fermentation is a chemical process of conversion of one type of carbon compound into another type of carbon compound by the action of micro-organisms.
3. Heat is generated in this process. Carbon dioxide (CO₂) and some other gases are released.
4. These gases cause an increase in volume so the bread dough rises.

Question g.
Fodder is soaked in water before offering to cattle.
Answer:

1. In dry fodder only some part of it is useful for cattle and rest is wasted.
2. When fodder is soaked in water, it sprouts.
3. So, to make the fodder more nutritious and more easy to digest it is soaked in water before offering to cattle.

7. When will you use a simple microscope and when a compound microscope?

Question a.
When will you use a simple microscope and when a compound microscope?
Answer:

1. I will use a simple microscope to magnify the objects and to see the growth of a fungi or mucor on a piece of moist bread.
2. I will use a compound microscope in Research Laboratory and high school science lab to observe micro-organisms which we are not able to see with our naked eye.

Project:

Question 1.
Visit a bakery in your area, collect information about the process of manufacture of their products and make one of them at home.

Class 7 Science Chapter 11 Cell Structure and Micro-organisms Important Questions and Answers

Fill in the blanks and rewrite the sentences:

Question 1.
………… is the fundamental, structural and functional unit of living organism.
Answer:
Cell

Question 2.
The four main parts of the plant cell are …………, …………, ………… and ………… .
Answer:
cell wall, cell membrane, cytoplasm, cell organelle

Question 3.
Plant cell contains ………… which carry out the process of photosynthesis.
Answer:
chloroplast

Question 4.
…………… are called the power houses of the cell.
Answer:
Mitochondria

Question 5.
The outermost covering of plant cell is …………. .
Answer:
cell wall

Question 6.
The outermost covering of animal cell is ………….
Answer:
plasma membrane

Question 7.
The ………… is the most important organelle of the cell.
Answer:
nucleus

Question 8.
………… is a national movement started several years ago to increase awareness about public hygiene and personal hygiene.
Answer:
Swach Bharat Abhiyan

Question 9.
The body temperature of a healthy human being is about ………… .
Answer:
37°C

Question 10.
Micro-organisms use food stuffs for their own nutrition and release toxic materials called ………. .
Answer:
enterotoxins

Name the following:

Question 1.
An instrument used to observe cells.
Answer:
Microscope

Question 2.
I control the function of a cell.
Answer:
Nucleus

Question 3.
I am like a policeman. I do not allow anything and everything to get in and out of the cell.
Answer:
Cell membrane

Question 4.
Outermost layer of the plant cell.
Answer:
Cell wall

Question 5.
Outermost layer of the animal cell.
Answer:
Cell membrane

Question 6.
I am the jelly like substance containing all the organelles.
Answer:
Cytoplasm

Question 7.
I contain thread like structures called chromosome.
Answer:
Nucleus

Question 8.
Which part of the cell contain organelles.
Answer:
Cytoplasm

Question 9.
The unit of measurement used for expressing dimension, size of the cell.
Answer:
Nanometer, micrometer

Question 10.
The power house of the cell.
Answer:
Mitochondria

Question 11.
Largest organelle in the plant cell.
Answer:
Vacuole

Question 12.
It is necessary for photosynthesis.
Answer:
Chlorophyll

Question 13.
The living substance in the cell.
Answer:
Cytoplasm

Question 14.
A group of cells.
Answer:
Tissue

Question 15.
Empty structures in cytoplasm.
Answer:
Vacuole

State whether the following statements are True or False. Correct and rewrite the false statement:

Question 1.
Cells can be easily seen with naked eyes.
Answer:
False. We can’t see cells with naked eyes, can be seen under microscope

Question 2.
A single cell can perform all the functions in a unicellular organism.
Answer:
True

Question 3.
Cell wall is present in both plant cells and animal cells.
Answer:
False. Cell wall is present only in plant cell

Question 4.
Vacuoles are not found in plant cell.
Answer:
False. Large vacuole is found in plant cell

Question 5.
Tissue is a group of dissimilar cells.
Answer:
False. Tissue is a group of similar cells.

Question 6.
Unicellular organisms have one celled body.
Answer:
True.

Question 7.
The basic living unit of an organism is an organ.
Answer:
False. The basic living unit of an organism is the cell.

Question 8.
The unit of measurement used for expressing dimension size of the cell is centimetre.
Answer:
False. It is nanometer.

Question 9.
Micro-organism cannot grow in extreme adverse conditions.
Answer:
False. Some micro-organisms can survive in extreme adverse conditions e.g. ocean floor, ice polar region, hot water spring.

Question 10.
Some micro-organisms can grow without oxygen.
Answer:
True

Question 11.
Amoeba has irregular shape.
Answer:
True

Question 12.
The process of fermentation is used for making yogurt from milk.
Answer:
True

Question 13.
Micro-organisms need an optimum temperature of 55°C to 70°C to grow.
Answer:
False. They need temperatures between 15°C to 35°C to grow well.

Question 14.
Cells with membrane bound organelles inside them are called prokaryotic cells.
Answer:
False. Cells with membrane bound organelles inside them are called eukaryotic cells.

Question 15.
Golgi bodies are the power houses of the cells.
Answer:
False. Mitochondria are the power houses of the cell.

Choose the correct word.

Question 1.
Which one of the following terms is not a part of the nucleus?
(a) ribosome
(b) DNA
(c) chromosome
(d) gene
Answer:
(a) ribosome

Question 2.
A suitable term for the various components of cell is.
(a) tissue
(b) cell organelle
(c) chromosome
(d) gene
Answer:
(b) cell organelle

Question 3.
The jelly like fluid substance present in the cells is called.
(a) protoplasm
(b) chromosome
(c) chloroplast
(d) cytoplasm
Answer:
(d) cytoplasm

Question 4.
The units of measurement used for expressing dimension size of the cell are,
(a) centimetre
(b) micrometre
(c) nanometre
(d) metre
Answer:
(c) nanometre, (b) micrometre.

Question 5.
The largest cell in the human body
(a) nerve
(b) muscle
(c) liver
(d) kidney
Answer:
(a) nerve

Question 6.
The barrier between protoplasm and other environment in animal cell
(a) plasma membrane
(b) cell wall
(c) nucleus membrane
Answer:
(a) plasma membrane

Question 7.
The term cell wall is given by
(a) Leeuwenhoek
(b) Robert Hooke
(c) Fleming
Answer:
(b) Robert Hooke

Question 8.
The cell theory was proposed by.
(a) Watsonar Cricks
(b) Schleiden
(c) Schwann
(d) Mengal Morgan
Answer:
(b) Schleiden, (c) Schwann.

Question 9.
Which of the following features will help you in distinguishing a plant cell from an animal cell.
(a) cell wall
(b) cell membrane
(c) mitochondria
(d) nucleus
Answer:
(a) cell wall

Question 10.
The gas released during the preparation of bread,
(a) O₂
(b) CO₂
(c) nitrogen
(d) sulphur oxide
Answer:
(b) CO₂

Question 11.
The structural-functional unit of life is called.
(a) cell
(b) tissue
(c) organ
(d) organism
Answer:
(a) cell

Question 12.
Which organelle is called power house of the cell?
(a) centrosome
(b) lysosome
(c) plastid
(d) mitochondria
Answer:
(d) mitochondria

Question 13.
Living substance of cell is called.
(а) cytoplasm
(b) protoplasm
(c) nucleus
(d) chromosome
Answer:
(а) cytoplasm

Give scientific reasons:

Question 1.
Mitochondria are called the power houses of the cell.
Answer:

1. Mitochondria are tiny organelles inside the cells that are involved in releasing energy from food.
2. This process is known as cellular respiration.
3. It is for this reason that mitochondria are often referred to as the power houses of the cell.

Question 2.
A compound microscope is used for observing cells.
Answer:

1. Cell are extremely minute in size.
2. We cannot see cells with naked eye.
3. An object when kept on a glass slide is magnified many times by the lenses of this microscope.
4. Hence, compound microscope is used for observing cells.

Question 3.
Cells are the basic structural units of living organism.
Answer:

1. Cells are the smallest unit from which a living organism is made.
2. A cell contains all the necessary structures which are required to carry out various biological processes.
3. A group of cells makes a tissue, which further makes an organ and many organs together make an organ system and finally organism. Thus, the cells are the basic structural units of living organism.

Answer the following in short:

Question 1.
What is a vaccine?
Answer:
Vaccine is a live micro-organism which is weak but in a very small amount, and is injected into a person so that antibodies are produced against that micro-organism.

Question 2.
What are the similarities between the Plant cell and Animal cell?
Answer:
They both have cell membrane, cytoplasm, nucleus, ribosomes, golgi bodies, mito-chondria, vacuoles and chromosomes.

Question 3.
What do micro-organisms need for growth?
Answer:
Micro-organisms need soil, water and decaying material. Temperature suitable for microbial growth is 15 to 35°C moist, humid and warm climate.

What is the difference between us:

Question 1.
Simple microscope and Compound microscope.
Answer:

Simple microscope	Compound microscope
1. It consists of single lens.	1. It consists of 2 lenses.
2. Magnification power is upto 300X	2. Magnification power is upto 2000X.
3. It uses natural light source.	3. It uses illumination as light source.
4. It is used to observe small objects.	4. It is used to observe very tiny objects or cells which we cannot see with naked eye.

Answer in details:

Question 1.
Explain the functions of organelles in a cell.
Answer:
1. Functions of cell wall: It consist of cellulose. It is present in plant cell only. It is a protective layer outside the cell membrane. It provides structural support and protection.

2. Function of cell membrane: It controls the movement of substances in and out of the cell. It protect the cell from its surrounding.

3. Function of cytoplasm: It is the jelly like liquid, it occupies space between cell membrane and nucleus. All the organelles are scattered in it.

4. Function of Nucleus: It is the brain of the cell. It directs all cell activities, and contains genetic material called chromosomes made of DNA.

5. Function of mitochondria: It is the power house of cell. It produces energy in the form of ATP from the food.

6. Vacuoles: It is the largest organelle in the plant cell surrounded by membrane. It holds material and waste. It maintains proper pressure. It helps to throw out waste products of cell.

Explain:

Question 1.
Ram ate chaat from a street hawker, when he reached home he fell ill and complained of stomach ache. What could be the reason?
Answer:

1. he chaat Ram ate from a street hawker must be contaminated with harmful micro-organism due to dirty water used in it or stale potato used in it.
2. Toxins are produced by micro-organisms in food.
3. Ram ate that and suffered from food poisoning.

Question 2.
With the help of diagram describe Prokaryotic cell.

Answer:

1. Prokaryotic cell do not have well-defined nucleus.
2. The plasma membrane, cytoplasm and nucleoid are the only components.
3. The prokaryotic cells have smaller ribosomes compared to eukaryotic cells.
4. Bacteria and blue green algae are examples of prokaryotic cell.

Question a.
Draw neat and labelled diagram of plant cell.
Answer:

Question b.
Draw neat and labelled diagram of animal cell.
Answer:

Name the types of cells shown in the diagrams.

Question 1.

Answer:

(a) A fat cell
(b) A nerve cell
(c) A sperm cell
(d) Spirogyra
(e) Red Blood cells

Try this:

Answer the following questions:

Question 1.
Keep a moistened piece of bread or bhakari in a closed box. What will you observe after 3-4 days?
Answer:

1. I will observe growth of fungus or mucor. White cotton like layer or black spots.
2. As we know fungus grows in presence of moisture.

Question 2.
Observe a drop of muddy water or water from a stagnant puddle, under the compound microscope.
Answer:

1. We will observe, living things, micro-organism, bacteria, fungi.
2. It will be swarming withbacteria,paramoecium, amoeba, ciliated bacteria and protozoa, etc.

Question 3.
Take a drop of yoghurt or buttermilk on a glass slide and observe it under a compound microscope.
Answer:

1. I will see Lactobacillus rod shapted bacteria and streptococcus spherical shape bacteria which may be in clusters.
2. Lactobacillus use lactose present in the milk and produce lactic acid which gives tangy taste to yoghurt.

Find out:

Answer the following questions:

Question 1.
Which diseases do micro-organism cause in plants and animals?
Answer:
Diseases caused by micro-organism in plants and animals are:

Plants	Animals
Cankers, Downy Mildew, Ergot, Root rot, Rust, Seed Decay, Smut, Soft rot, Wilts, Leaf spot, Crown gel, Curly top, Mosaic leaf, Yellowing of leaf etc.	Anthrax in cattle, Dysentery in monkey, Diphtheria in rabbit, Tuberculosis in cattle, Plaque in rats.

Question 2.
Why are infants vaccinated according to fixed time schedule?
Answer:
Vaccination is done to protect the child against diseases.
1. If a baby is vaccinated by true vaccine schedule, that baby will have immunity to over 14 diseases by the age of two. With the recommended schedule, babies visit their doctor 5 times in the first 15 months and receive protection against upto 14 diseases in as little as 18 shots.
2. We immunize children so young against these diseases because infancy is the time period that kids are most vulnerable to life threatening diseases.
3. It is not advisable to skip or delay vaccines as this will leave the child vulnerable to disease for a longer period of time.

Can you tell?

Answer the following questions:

Question 1.
Observe cells from various parts of plants like leaves, bark, root tips, etc.
Answer:
Question a.
Are the cells that you observed, all alike?
Answer:
No, all cells do not look alike, each one has different shape and size.

Question b.
What are their shapes?
Answer:

1. The cells of leaves, show a green pigment because of chloroplast.
2. The shape of the cell may be spherical or polygonal.
3. The shape of root tips are oval or polygonal and the cells of back are hexagonal in shape.

Question 2.
Observe the roots of the pea, bean and fenugreek plants. What could be the functions of the nodules on their roots.
Answer:

1. Micro-organisms are present in the root nodules.
2. They fix the atmospheric nitrogen and make it available for plants.

Question 3.
What happens if clothes remain damp in the rainy season?
Answer:

1. During rainy season the humidity in the air is quite high and also.
2. Due to presence of moisture in clothes it becomes breeding ground for fungus.
3. It is the favourable condition for growth of fungus.
4. We can see white cotton like growth of fungus on clothes.

Question 4.
What are the black or white spots sometimes seen on gunny bags?
Answer:
These spots are the growth of many microbes such as fungi, mucus, mold, etc.

Question 5.
Why are leather articles like purses, wallets, belts, footwear always polished before storing away?
Answer:
They are polished so as to protect them from the growth of fungus.

1. Polish creates a layer of wax on them so that moisture cannot enter from atmosphere.
2. It prevents the growth of fungus, which damages the leather.

Question 6.
What is the powdery material found on old currency notes or old rubber or paper?
Answer:

1. The powdery material is the spores of fungi.
2. All the materials like gunny bags, cotton clothes, paper, rubber, etc. are plant products and leather is an animal product.
3. In a humid atmosphere, fungi and some other micro-organisms grow on these articles and spoil or damage them.

Question 7.
Why children are vaccinated?
Answer:

1. A vaccine is produced in a laboratory with the help of microbes, that gives immunity against particular diseases.
2. Vaccine is actually a live micro-organism which is weak.
3. When injected into a person in small amount, antibodies are produced.
4. It increases the resistance power against the disease produced by that micro-organism. So, the possibility of contracting that disease is greatly reduced.

Question 8.
Try this and answer the following questions:

In pot A	In pot B
Soil + garden waste + dung + fruit peel vegetable stalks	Pieces of glass + scrap metal + plastic bags + Soil.

Question a.
Did the garbage in pot B remain unchanged.
Answer:

1. Yes, the garbage in pot B remained unchanged because micro-organisms need nutrients for their growth.
2. In pot B there was no medium for growth of micro-organisms.

Question b.
Where did the garbage in pot ‘A’ disappear? Why?
Answer:

1. Microbes present in soil, dung, etc. decompose the garbage to obtain food material.
2. As a result garbage is soon converted into manure of the best quality and our surroundings are kept clean.

Question 9.
What does your mother do to make yoghurt from milk?
Answer:

1. Few drops of yoghurt or buttermilk are mixed with lukewarm milk and it is kept at room temperature for 8-10 hours.
2. Microbes present in the drops of yoghurt quickly multiply and the milk gets converted into yoghurt. This is a process of fermentation.

Question 10.
Who discovered the process of fermentation?
Answer:

1. Louis Pasteur established that fermentation is initiated by living organisms.
2. It involves yeast microbes, breaking down molecules of complex carbohydrates into simple sugar, alcohol and CO₂.

Use your brain power!

Answer the following questions:

Question 1.
How will you know that a foodstuff is spoilt?
Answer:

1. When the food is kept for a long time it allows the growth of bacteria and fungi.
2. We can see the white layer of bacterial or fungal growth on it, it causes a typical odour, or smell, and also the food tastes sour due to presence of enterotoxins produced by fungi in the food.

Question 2.
What precautions will you take while purchasing food? Why?
Answer:

1. We will see the expiry date. If the food is kept for a long period of time, it may allow the growth of many microbes which can cause disease or food poisoning.
2. We will check for any fungal growth, any white or black spots on it.

Question 3.
Why do food poisoning incidents occur during marriage or other community feasts?
Answer:
1. During marriage feast, food is prepared in very large quantity and food may not be properly washed or if it is cooked with water contaminated, with sewage or dirt which has many disease causing microbes, or the people handling the food may be having dirty hands

2. Also the utensils used for cooking and storing food may be dirty, contaminated with dirt and may produce microbes. The consumption of such food is responsible for food poisoning.

Question 4.
How do the cells acquire definite shapes?
Answer:
The cells acquire definite shapes due to the presence of cell wall.

Question 5.
How are cells protected?
Answer:

1. Plant cells are protected due to presence of cell wall.
2. Animal cells are protected by the double plasma membrane.

Question 6.
What are the needs of cells?
Answer:

1. The most important things for a cell are oxygen and glucose.
2. Cell uses these during process of glycolysis and makes ATP which is energy source.

Question 7.
Can the point of a needle accommodate micro-organism?
Answer:
Yes, they are smaller than the point of a needle.

Question 8.
Why should dry and wet waste be collected separately?
Answer:

1. Dry waste consist of plastic, glass, metals, paper, etc. It is easier to segregate dry waste so that it is easier for treatment and recycling of waste.
2. Wet waste consists of organic matter. Wet garbage is converted into manure of the best quality and surroundings are kept clean.

Question 9.
Why is yoghurt mixed in the batter or dough for making rava-idli, butter naan?
Answer:

1. The microbes present in yoghurt are allowed to grow in batter or dough.
2. They break down these substances producing new compound and gases are released as they grow and multiply in them which allows the batter, dough to rise.
3. This process is called fermentation.
4. This makes the food soft and nutritious.

Question 10.
How do preparation like yoghurt, idli, dosa become easy to digest?
Answer:
Fermentation does detoxification and splits complex carbohydrates and proteins into simple ones. Thus, making it easy to digest.

Question 11.
What is the co-relation between the normal body temperature of humans which is 37°C and the optimum temperature for the growth of micro-organism, 15 °C to 35 °C?
Answer:

1. Each micro-organism needs a specific environment for growth and reproduction.
2. Optimum temperature for the growth of micro-organism is 15°C to 35°C.
3. Normal body temperature of human body is 37°C. At that temperature micro-organism can not grow and cause disease.

Question 12.
How do micro-organism survive the adverse conditions?
Answer:

1. During adverse conditions micro-organisms form a thick covering around themselves and stop their life processes.
2. On return of favourable conditions they come out of the protective covering and continue their life processes.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 7 Motion, Force and Work Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 7 Motion, Force and Work

Class 7 Science Chapter 7 Motion, Force and Work Textbook Questions and Answers

1. Fill ¡n the blanks with the proper words from the brackets.
(stationary, zero, changing, constant, displacement, velocity, speed. acceleration, stationary but not zero. inc reuses)

Question a.
If a body traverses a distance in direct proportion to the time, the speed of the body is ……………… .
Answer:
constant

Question b.
If a body is moving with a constant velocity, its acceleration is ……………… .
Answer:
zero

Question c.
……………. is a scalar quantity.
Answer:
Speed

Question d.
…………….. is the distance traversed by a body in a particular direction in unit time.
Answer:
Velocity

2. Observe the figure and answer the questions.

Sachin and Sarneer started on a motorbike from place A, took the turn at 13, did a task at C, travelled by the route CD to D and then went on to E. Altogether, they took one hour for this journey. Find out the actual distance traversed by them and the displacement from A to E. From this, deduce their speed. What was their velocity from A to E in the direction AE’? Can this velocity be called average velocity?

Question a.
Observe the figure and answer the questions

Sachin and Sarneer started on a motorbike from place A, took the turn at 13, did a task at C, travelled by the route CD to D and then went on to E. Altogether, they took one hour for this journey. Find out the actual distance traversed by them and the displacement from A to E. From this, deduce their speed. What was their velocity from A to E in the direction AE’? Can this velocity be called average velocity?
Answer:
1. Actual distance = \(\overline{\mathrm{AB}}\) + \(\overline{\mathrm{BC}}\) + \(\overline{\mathrm{CD}}\) + \(\overline{\mathrm{DE}}\) = 3 + 4 + 5 + 3
Actual distance = 15 km

2. Displacement = \(\overline{\mathrm{AB}}\) + \(\overline{\mathrm{BD}}\) + \(\overline{\mathrm{DE}}\)
= 3 + 3 + 3
Displacement = 9 km

3. Speed = \(\frac{\text { Distance travelled }}{\text { Total time }}\)
Distance = 15 km = 15 × 1000 = 15000 m
Time = 1 hr = 1 × 60 × 60 = 3600 sec.
s = \(\frac{15000}{3600}\) or s = \(\frac{15 \mathrm{~km}}{1 \text { hour }}\) = 15km/hour
= 4.16 m/sec. or 15 km/hour

4. Velocity = \(\frac{\text { Distance travelled }}{\text { Total time }}\)
Displacement = 9 km = 9 × 1000 = 9000 m
Time = 1 hr = 1 × 60 × 60 = 3600 sec
V = \(\frac{9000}{3600}\) or V = \(\frac{9 \mathrm{~km}}{1 \text { hour }}\) = 9 km/hour
= 2.5 m/sec. or 9 km/hour

5. Yes, this velocity can be called as average velocity.

3. From the groups B and C, choose the proper words, for each of the words in group A.

Question a.
From the groups B and C, choose the proper words, for each of the words in group A.

Answer:

Group ‘A’	Group B’	Group ‘C’
Work	Joule	erg
Force	Newton	dyne
Displacement	Metre	cm

4. A bird sitting on a wire, flies, circles around and comes back to its perch. Explain the total distance it traversed during its flight and its eventual displacement.

Question a.
Answer:
The total distance the bird has traversed is the length of the distance covered by circling, but the eventual displacement are the bird is zero as its initial and final position are one and the same.

5. Explain the following concepts in your own words with everyday examples: force, work, displacement, velocity, acceleration, distance.

Question a.
Explain the following concepts in your own words with everyday examples: force, work, displacement, velocity, acceleration, distance.
Answer:
1. Force: The interaction that brings about the acceleration is called force.
e.g: An ox is pulling a cart, applying brakes to a bicycle, lifting heavy iron object with a crane.

2. Work: When an object is displaced by applying a force on it, work is said to be done.
e.g: A bucketful of water is to be drawn from a well and taken to the home by walking from well to home.

3. Displacement: The minimum distance
traversed by a moving body in one direction from the original point to reach the final point is called displacement.
e.g: A rolling of a ball from point A to point B in the same direction.

4. Velocity: Velocity is the distance traversed by a body in a specific direction in unit time.
e.g: A truck is covering a distance of 40km from A to D in a straight line in 1 hour.

5. Acceleration: It is change in velocity per second. It can be deduced.
Acceleration = \(\frac{\text { Change in velocity }}{\text { Time taken for change }}\)
e.g:

(i) In the above example a truck covered the distance AB at velocity of 60 km/hr, BC at 30 km/hr and CD at 40 km/hr. (ii) It means that the velocity for the distance CD is greater than the velocity for the distance BC. (iii) From the number of seconds required for this change in velocity to take place, the change in velocity per second can be deduced. This is called acceleration (iv) Distance: The length of the route actually traversed by a moving body irrespective of the direction is called distance.
e.g: Ranjit travelled 1km. from his home to school.

6. A ball is rolling from A to D on a flat and smooth surface. Its speed is 2 cm/s. On reaching B, it was pushed continuously up to C. On reaching D from C, its speed had become 4 cm/s. It took 2 seconds for it to go from B to C. What is the acceleration of the ball as it goes from B to C.

Question a.
A ball is rolling from A to D on a flat and smooth surface. Its speed is 2 cm/s. On reaching B, it was pushed continuously up to C. On reaching D from C, its speed had become 4 cm/s. It took 2 seconds for it to go from B to C. What is the acceleration of the ball as it goes from B to C.

Answer:
As its initial and final positions are one and the same.
Initial Velocity = 2 cm/s.
Final Velocity = 4 cm/s
Time taken for the change in velocity from B to
D = 4 cm/s – 2 cm/s = 2 cm/s

7. Solve the following problems.

Question a.
A force of 1000 N was applied to stop a car that was moving with a constant velocity. The car stopped after moving through 10m. How much is the work done?
Answer:
Force (F) = 1000 N
displacement (s) = 10m
work done (W) = ?
W = Fs
= 1000 × 10
W = 10,000 Joule

Question b.
A cart with mass 20 kg went 50 m in a straight line on a plain and smooth road when a force of 2 N was applied to it. How much work was done by the force?
Answer:
Force (F) = 2 N
Displacement (s) = 50 m
Work done (W) = ?
W = Fs
= 2 × 50
W = 100 Joule

Project:

Question a.
Collect information about the study made by Sir Isaac Newton regarding force and acceleration and discuss it with your teacher.

Class 7 Science Chapter 7 Motion, Force and Work Important Questions and Answers

Fill in blanks:

Question 1.
Displacement is a …………. quantity.
Answer:
vector

Question 2.
The …………. of an object can change even while it is moving along a straight line.
Answer:
velocity

Question 3.
The …………. velocity can be different at different times.
Answer:
instantaneous

Question 4.
Change in velocity per second is called …………. .
Answer:
acceleration

Question 5.
The interaction that brings about the acceleration is called …………. .
Answer:
force

Question 6.
The scientist …………. was the first to study force and the resulting acceleration.
Answer:
Sir Isaac Nezvton

Question 7.
Ability to do work is called …………. .
Answer:
Energy

Question 8.
W = …………. × S.
Answer:
F

Question 9.
Unit of work is …………. and …………. .
Answer:
Joule, erg

Question 10.
Unit of force is …………. and …………. .
Answer:
Newton, dyne

Question 11.
Force is a …………. quantity.
Answer:
vector

Question 12.
The velocity at a particular time is called …………. velocity.
Answer:
instantaneous

Question 13.
The …………. of a body is the distance traversed per unit time.
Answer:
speed

Question 14.
Unit of acceleration is …………. and …………. .
Answer:
m/s² and cm/s²

Question 15.
Force is measured by the …………. that it produces.
Answer:
acceleration

Question 16.
Work done by a body with no displacement will be …………. .
Answer:
zero

Say whether True or False, correct the false 1 statements:

Question 1.
Velocity is distance travelled per unit of time.
Answer:
False. Speed is distance travelled per unit of time

Question 2.
In displacement, both distance and direction are taken into account.
Answer:
True

Question 3.
Speed = Distance/time.
Answer:
True

Question 4.
Change in speed per second is acceleration.
Answer:
False. Change in velocity per second is acceleration

Question 5.
Work done depends on the force and the displacement.
Answer:
True

Question 6.
C.G.S. unit of acceleration is m/s².
Answer:
False. C.G.S. unit of acceleration is cm/s².

Question 7.
M.K.S. unit of force is dyne.
Answer:
False. M.K.S. unit of force is Newton

Question 8.
Force is measured by the acceleration that it produces.
Answer:
True

Write the difference between the following:

Question 1.
Speed and Velocity
Answer:

Speed	Velocity
1. Speed is distance travelled per unit of time.	1. Velocity is the distance traversed by a body in a specific direction in unit time.
2. It is a scalar quantity.	2. It is a vector quantity.
3. Formula: Speed = \(\frac{\text { Distance traversed }}{\text { Total time }}\)	3. Formula: Velocity = \(\frac{\text { Displacement }}{\text { Total time }}\)

Question 2.
Distance and Displacement
Answer:

Distance	Displacement
1. The length of the route actually traversed by a moving body, irrespective of the direction is called distance.	1. The minimum distance traversed by a moving body in one direction from the original point to reach the final point is called displacement.
2. It is a scalar quantity.	2. It is a vector quantity.

Solve the following problems!

Question 1.
A bus travelled 200 km in the first 3 hours and then 100 kms for the next one and a half hours and then 120 kms for the next one and a half hours. What is the average velocity of the bus if it has moved in a straight line for the whole journey.
Answer:

Question 2.
See the diagram and calculate the Distance and Displacement travelled by the body from A to I.

Answer:
Distance travelled =
A → B → C → D → E → F → G → H + I
= 5 + 7 + 6 + 3 + 5 + 4 + 6 + 5
= 41 m
Displacement = A → I in a straight line shortest distance
= 1m

Use your brainpower:

Question 1.
The unit of acceleration is m/s², verify this.
Answer:

Question 2.
Acceleration is a vector quantity. Is force a vector quantity too?
Answer:
Yes, acceleration and force both are vector quantities, because both can be expressed completely only when magnitude and direction are given and the quantity which needs direction and magnitude both is called a vector quantity.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 10 Disaster Management Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 10 Disaster Management

Class 7 Science Chapter 10 Disaster Management Textbook Questions and Answers

1. Find the odd man out:

Question a.
Famine, earthquake, cloudburst, railway accident.
Answer:
Railway accident.

Question b.
Drought, heavy rains/storm, tsunami.
Answer:
Drought.

Question c.
Lava, hot mud, ash, locusts.
Answer:
Locusts.

Question d.
Washing away of crops, attack of pests on crops, volcano, singeing of crops.
Answer:
Volcano.

2. What are the remedial measures for the following calamities?

Question a.
Famine:
Answer:
Following are the remedial measures for famine:

1. Supply food and water to the people those who are dying due to hunger.
2. Give medicines to the people those who are suffering from malnutrition.
3. Government should start helping centres for the people those who are suffering from famine.
4. Give them temporary shelter in some other places where water and food are available.
5. Shift the animals to safer places.
6. Do proper planning so that region doesn’t get famine again and again.
7. Reuse water
8. grow more trees.

Question b.
Lightning strike:
Answer:
Following are the remedial measures for lightning strike:

1. Give immediate treatment to the lightning affected persons so their life can be saved.
2. Keep the people away from the open ground and swimming pool.
3. Provide them proper guidelines to cure for the lightning strike.

Question c.
Storm:
Answer:

1. Supply food, water and medicines to the people
2. Shift them to safe places.
3. Maintain peace, and advice the people not to panic.
4. Give time to time report on T.V. and radio.

Question d.
Cloudburst:
Answer:
Following are the remedial measures for cloudburst:

1. Shift people to safe places with the help of airplane, helicopter and army.
2. Supply them food, clothes, water and medicines.
3. Give time to time weather report.
4. Open more helpline centres.
5. Government should immediately send the help in terms of money and army to the people.

3. True or false? Give reasons for your answer.

Question a.
Information about a forthcoming storm is to be kept secret.
Answer:
False. Information about a forthcoming storm is not to be kept secret because, with this information we can take immediate steps for disaster management. Large scale damage of property and loss of life can be avoided.

Question b.
You should not swim when there is lightning in the sky.
Answer:
True. Lightning carries some electric charges which causes electric current in it. Water catches this current so if any person is swimming pool during lightning in the sky, then there are more chances that lightning may strike in water and the person may die due to it.

Question c.
It is possible to prevent the eruption of a volcano.
Answer:
False. It is not possible to prevent the eruption of a volcano because it is a natural event. However, by means of science and technology, it is possible to predict an eruption in advance and to take immediate steps for disaster management.

Question d.
Heavy rains result in famine.
Answer:
True. Heavy rains result in flood so crops get washed away or damaged in the flood and results in famine.

Question e.
A loud crashing sound follows a lightning.
Answer:
True, Friction and brushing happens between two clouds making them charged and lightning is produced between two clouds or one cloud and earth. The temperature increases and air pressure also increases to high amount and produces a loud sound of thunder.

4. Write answers to the following questions in our own words.

Question a.
What is a tsunami? What gives rise to a tsunami?
Answer:

1. Waves generated by an earthquake or volcano occurring on the ocean floor is called ‘tsunami’. ‘Tsunami’ is a Japanese word which means ‘harbour wave’.
2. As on land, earthquakes and volcanic eruptions occur, at the bottom of the sea, too.
3. If an earthquake occurs at the bottom of ocean, the energy released pushes the water upwards. As a result of this particular type of waves are formed.
4. These waves are not very high near the source, but they start spreading very fast to long distances.
5. The velocity of these waves is 800 to 900 km/hr. When they reach a coastal area, their velocity is reduced, but their height is found to have increased tremendously even to about 30 m. These are tsunami waves.

Question b.
What is cloudburst?
Answer:

1. Sometimes the water coming down from rain clouds does not reach the land in the form of rain. Instead, due to very high temperature near the land, it vaporizes and goes back into the same clouds.
2. As a result the amount of vapour in those clouds becomes very high.
3. Due to rapid condensation, it rains suddenly over a specific and small region at a rate of 100 mm per hour or more. This is known as a cloudburst.

Question c.
Explain the effects of a volcano.
Answer:
Following are the effects of a volcano:

1. The chemical substances such as lava, vapour, hot mud, sulphur etc. get collected on the surface of the earth and thereby mountains and hills are created
2. The atmosphere gets polluted due to the ash and gases ejected by the volcano.
3. Often, it rains as a result of a volcanic eruption.
4. The temperature rises due to hot gases.
5. Forests and settlement get buried under the hot mud.

Question d.
What are the measures to prevent loss of life due to lightning?
Answer:
Following are the measures to prevent loss of life due to lightning:

1. Do not stand on open ground, below a tree, on high location, near an electric pole, near a telephone pole or a tower etc.
2. Do not lean on wire fences around a farm, a compound, a garden or a house.
3. If you are on two-wheeler, a bicycle, a tractor or a boat, get off immediately and go to safe place.
4. Do not gather all together in one place.
5. Take care to keep a distance of 15 feet between any two persons.
6. Do not use plugged in electrical appliances. Do not use a mobile or telephone.
7. Stand on dry wood, a plastic sheet, sack or jute cloth or dry leaves.
8. Keeping your feet together support yourself on the soles of your feet placing your hands on your knees and crouch low.
9. Swimmers and fishermen should immediately come out of the water.
10. A pucca house is the safest place. Find out if there is a lightning conductor on any tall building near your house. If necessary get a lightning conductor fitted on your house.

5. What measures have been taken to deal with calamities such as floods and landslides under the disaster management programme in Maharashtra?

Question a.
What measures have been taken to deal with calamities such as floods and landslides under the disaster management programme in Maharashtra?
Answer:
In Maharashtra, all districts have their own disaster management plan to deal with calamities such as floods and landslides.

1. The plan deals extensively with the emergency, and evacuation measures to be taken up in cases of flood and landslide.
2. The district-level disaster management plan has detailed information about geographical details, population, flood-prone areas, villages and other macro details.
3. Nearly 14 such key departments are engaged in disaster mitigation measures and each one has been assigned a specific task to do at times of natural disasters.
4. The administration is now training master trainers at the district level who in turn will train key persons at village and taluka levels to deal with a natural disaster.
5. The administration through radio jingles, public advertisements and other measures is informing people about how to react at times of flood and landslide.
6. Currently, the Indian Meteorological Department (IMD) gives weather forecast on daily basis and for the next 5 days with advice to farmers on when to start crop sowing and harvesting etc.

6. With reference to disaster management what are the things in your house that you will check?

Question a.
With reference to disaster management what are the things in your house that you will check?
Answer:
With reference to disaster management, we should keep the following things at home and check regularly.

1. Keep proper first aid kit at a handy place.
2. Keep all the electric connections in proper condition.
3. Keep the gas line or tube connection proper.
4. Keep self-powered flashlights and self-powered radios.
5. Keep non-perishable food which will last for a week.
6. Keep a fire extinguisher handy and in proper condition.
7. Keep updated telephone diary which should have emergency phone numbers.

Project:

Question 1.
With the help of the Internet, collect information about the places where a calamity has occurred.

Question 2.
Collect information from the Internet about how cyclonic storms are named.

Class 7 Science Chapter 10 Disaster Management Important Questions and Answers

Fill in the blanks:

Question 1.
………… and ………… disasters are related to each other.
Answer:
Natural manmade.

Question 2.
………… implemented a canal scheme for drinking water in Aurangabad.
Answer:
Malik Ambar.

Question 3.
………… has turned out to be the most famine-affected contents of the world.
Answer:
Asia

Question 4.
The government of India established the ………… in 1976.
Answer:
National Flood Commission

Question 5.
The ………… that occurred in Mumbai on 26th August 2005 was extraordinary and unforgettable.
Answer:
cloudburst.

Question 6.
A cloudburst occurred at ………… on 6th August, 2010.
Answer:
Ladakh (Leh)

Question 7.
About ………… lightning flashes occur per second in the atmosphere.
Answer:
40.

Question 8.
The temperature generated by ………… is higher than that of the sun.
Answer:
lightning

Question 9.
When some substances comes out of the earth’s crust in an eruption and start flowing is called a ………… .
Answer:
volcano

Question 10.
Some islands are created due to the eruption, of ………… in the sea.
Answer:
volcano

Question 11.
………… is a Japanese word which means ‘harbour wave’.
Answer:
Tsunami.

Question 12.
About ………… nations from all over the world are members of the UNDP.
Answer:
177.

Question 13.
………… established a standing international organization UNDP in 1965.
Answer:
United Nations.

Question 14.
………… is celebrated as International Day for Disaster Reduction.
Answer:
13th October

Question 15.
The condition that arises due to long term and severe scarcity of food grains and water is called………. .
Answer:
famine

Can you tell?

Question 1.
Is it possible to prevent the loss of life caused by lightning?
Answer:
Yes, it is possible to prevent the loss of life caused by lightning, by taking precautions.

Question 2.
What should be done to prevent the bunds on a farm from getting washed away in the rainy season?
Answer:

1. Grow more trees near the bunds.
2. Grow grass strips.
3. Make stone lines near the bunds.
4. Use contour ploughing and tillage network method to prevent the bunds on a farm from getting washed away in the rainy season.

Question 3.
Why do we experience water scarcity?
Answer:
Lessor no rain leads to water scarcity.

Question 4.
What causes rain?
Answer:

1. Due to heat of the sun, water from the sea, lake and river gets evaporated and this water vapour is light in weight so it goes higher and higher and forms the cloud.
2. At a certain level the amount of vapour in those clouds becomes very heavy and it burst and rain occurs.

Question 5.
Have you seen a flash of lightning in the sky? When?
Answer:
Students will answer this question based on their experience.

Question 6.
What causes lightning?
Answer:

1. Where air and clouds rub against each other in the sky, the upper part of some clouds on the upper side becomes positively charged and the lower sides become negatively charged.
2. When this negative charge on the bottom of the cloud becomes much larger than the charge on the ground it starts flowing towards the ground in stages.
3. This happens very fast, in much less than a second and heat, light and sound energy are produced along with the electric current.

Use your brainpower!

Answer the following questions:

Question 1.
We should not wait at the foothill while it is raining heavily.
Answer:
During heavy rain there are chances of landslide and flood, so we should not wait at the foothill while it is raining heavily.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 12 The Muscular System and Digestive System in Human Beings Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 12 The Muscular System and Digestive System in Human Beings

Class 7 Science Chapter 12 The Muscular System and Digestive System in Human Beings Textbook Questions and Answers

1. Fill in the blanks with the right word from the brackets:

Question a.
The process of digestion starts from the ………….. (stomach, mouth).
Answer:
mouth

Question b.
Eyelids have …………… muscles. (voluntary, involuntary)
Answer:
involuntary

Question c.
……………. is not a function of muscular system. (production of blood cell, performing movement)
Answer:
Production of blood cells

Question d.
Muscles of the heart are …………….. . (ordinary muscles, cardiac muscles)
Answer:
cardiac muscles

Question e.
Pushing forward the food that has been chewed is the function of the …………… . (stomach, oesophagus)
Answer:
Oesophagus.

2. Find a match for me.

Question a.

Column ‘A’	Column B’
1. Cardiac muscle	a. Always functions in pairs
2. Are brought about by muscle	b. We never feel tired
3. Pepsin	c. Uncontrolled and painful contraction of muscles
4. Cramps	d. Chewing movement of the jaw
5. Skeletal muscles	e. Enzymes of the gastric juice

3. Who is telling a lie?

Question a.

Organ	Statement
1. Tongue	a. My taste buds can tell only a sweet taste.
2. Liver	b. I am the largest gland in the body.
3. Large intestine	c. I am 7.5 metre long.
4. Appendix	d. Digestion is impossible without me
5. Lung	e. I play an important role in excretion.

Answer:

1. Lie. My taste buds can tell all tastes – sweet sour, bitter.
2. Truth.
3. Lie. It is 1.5 metre long.
4. Truth.
5. Lung → Lie. It plays important role in breathing.

4. Give reasons.

Question 1.
Food becomes acidic in the stomach.
Answer:

1. The gastric glands of stomach secrete gastric juice.
2. Food that has entered stomach is churned.
3. Three components of gastric juice namely hydrochloric acid, pepsin and mucus are mixed with food here and the food becomes acidic.

Question 2.
Cardiac muscles are said to be involuntary muscles.
Answer:

1. Cardiac muscles are found in the heart.
2. These muscles bring about the contraction and relaxation (beating) of the heart.
3. Their movement is involuntary.
4. Cardiac muscles cause our heart to relax and contract continuously at a rate of about 70 times per minute. They do not depend upon our will.
5. Beating is carried out in their own fixed manner.

So cardiac muscles are said to be involuntary muscles.

Question 3.
Intoxicating substances should not be consumed.
Answer:

1. Physical health is important for our organ system to function properly.
2. But harmful habits like smoking, chewing of tobacco, drinking alcohol affect our health adversely.
3. If we consume any tobacco products, the mouth, pharynx, alimentary canal, and other organs of the digestive system cannot function properly.
4. It causes problems like vomiting, nausea, and headache.
5. Tobacco particles stick to teeth, gums, and skin of the mouth cavity and slowly cause injury to those parts resulting in their dysfunction.
6. This causes swelling of the gums and pain when moving the jaws.
7. The pharynx and intestine become inflamed it progress into cancer leading to death.

Question 4.
Your muscles should be strong and efficient.
Answer:
Muscles are bundles of fibres that can contract and relax as required.

1. The action of muscles is necessary for all kinds of movements from the small movements of eyelid to those that demand great strength when chopping wood with an axe.
2. We use muscles for various movements like talking laughing, walking, jumping, throwing etc.
3. Therefore our muscles should be strong and efficient to do our day today work well and smooth functioning of life processes.

5. Answer the following. 

Question a.
How many types of muscles are there? Which are those types?
Answer:
Muscles are bundles of fibres that can contract and relax as required. There are three types of muscles.

• Skeletal muscles.
• Heart or cardiac muscles.
• Smooth muscles.

1. Skeletal muscles: (a) Skeletal muscles work with bones, the two ends of each of these muscles are attached to two different bones. (b) They are responsible for holding the bones of the skeleton together and giving shape to our body, (c) Skeletal muscles permits movement of t the body and maintain the posture of the body. (d) Skeletal muscle is voluntary e.g. muscles in our arms and legs are voluntary muscles, their action depends upon our will. That’s why they are called voluntary muscles.

2. Heart or cardiac muscles: (a) Heart or cardiac muscles bring about the contraction and relaxation (beating) of the heart. (b) Their movement is involuntary, (c) Cardiac muscles cause our heart to relax and contract continuously at a rate of about 70 times per minute, (d) Cardiac muscle is found in heart.

3. Smooth muscles: (a) These muscles are present in the internal organs other than the heart, e.g. muscles of the stomach, intestine, blood vessels, uterus etc. (b)Their movements are involuntary and slow, (c) They are not according to our will. (d) Various vital functions of our body such as digestion, respiration and movement of food material of which we remain quite unaware, are carried out by these special muscles.

Question b.
What causes the problem of acidity? What is its effect on the body?
Answer:

1. Stress is the main cause of acidity.
2. Hectic lifestyle and stress can lead to unhealthy or irregular meals, not good for digestion process, and this may cause acidity.
3. Other reasons are eating spicy food, drinking too much alcohol, missing meals, an empty stomach may lead to acidity.
4. Acidity leads to stomach upset, burning sensation in chest and stomach, constriction of blood vessels, weight gain, obesity, cardiovascular damage.

Question c.
Name the different types of teeth. What is the function of each type?
Answer:
There are four types of teeth, namely incisors, canines, pre-molars, and molars.
Each tooth is covered by a hard substance called enamel. Enamel is made up of calcium salt.
The process of digestion begins with the function of the teeth in the mouth.
1. Incisors: (a) These come in first 6-months of age. Incisors are the eight teeth in the front and centre four on top and four on bottom, (b) They are sharp and blade like for cutting food. e.g. for biting an apple, (c) We use them to take first bite of food.

2. Canines: (a) These are strong and pointed, sharpest of all for tearing food. e.g. to tear off a piece of tough meat, (b) They play important role in digestion of food, (c) They appear between 11 and 20 months of age.

3. Pre-molar: Pre molar share features of both canines and molars. (a) You can use them for grinding and chewing food. So that it becomes semi-liquid helping to gulp down the throat easily, (b) They are situated at each side of your mouth in deep settings, (c) They appear at the age of 10 years.

4. Molar: (a) These are broad and flat on top for crushing and grinding food. e.g. to grind up nutmeats. (b) Two teeth above and two teeth below, they appear at the age 11-13 years. (c) Molars are more prone to germ attack because of their remote location in our mouth.
So we should keep them clean.

6. Sketch and label a diagram of the digestive system and describe it in your own words.

Question a.
Sketch and label a diagram of the digestive system and describe it in your own words.
Answer:

1. Conversion of food into a soluble form and its absorption into the blood is called digestion.
2. The digestive system consists of the alimentary canal and digestive glands.
3. The total length of alimentary canal is about 9 metres.
4. Its main parts are the mouth, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus.
5. The salivary glands, liver, pancreas are the digestive glands connected to the alimentary canal.
6. Different organs of the digestive system perform the function of digestion.
7. There are different stages in the process of digestion of food.
8. The process of digestion begins with the function of the teeth in the mouth, food is chewed into small pieces.
9. There are four types of teeth, incisors, canines, pre-molars and molars.
10. Saliva in the mouth contains enzymes, ptyalin, or amylase. It converts starch into maltose.

a. Oesophagus:

1. It is a tube leading from the pharynx to the stomach,
2. It pushes the food towards the stomach.

b. Stomach:

1. The large sac like part of the alimentary canal is called the stomach.
2. Food that has entered is churned.
3. The gastric glands of stomach secrete gastric juice which contain hydrochloric acid, pepsin and mucus.
4. They mix with food and food becomes acidic.
5. Mainly proteins are digested in stomach.
6. Due to the churning and actions of gastric juice, food become a semi-solid slurry which is pushed into the small intestine.

c. Small intestine: (6m long)

1. Bile secreted by liver mixes with food in small intestine,
2. Most of the digestion and absorption of food takes place here.

d. Large intestine: (1.5m long) only water is absorbed in the large intestine. Undigested remain is thrown out of the body through the anus.

Project:

Question 1.
Make charts about maintaining good health.

Question 2.
Design a power point presentation about the digestive system and present it in the class.

Class 7 Science Chapter 12 The Muscular System and Digestive System in Human Beings Important Questions and Answers

Choose and write the correct word.

Question 1.
The structure that connects bones to the muscles is the ………………….. .
(a) ligament
(b) tendon
(c) fascicle
(d) skin
Answer:
(b) tendon

Question 2.
………………….. is not performed by muscles.
(a) Motion
(b) Excretion
(c) Maintenance of posture
(d) Heat production
Answer:
(d) Heat production

Question 3.
Approximately ………………….. skeletal muscles are there in the human body.
(a) 1000
(b) 600
(c) 100
(d) 60
Answer:
(b) 600

Question 4.
Most of the fat digestion occurs in ………………….. .
(a) rectum
(b) stomach
(c) small intestine
(d) large intestine
Answer:
(c) small intestine

Question 5.
Protein digestion is accomplished in ………………….. .
(a) stomach
(b) ileum
(c) rectum
(d) duodenum
Answer:
(b) ileum

Question 6.
The main function of the muscular system is ………………….. .
(a) excretion
(b) digestion
(c)movement
(d) contraction
Answer:
(c)movement

Question 7.
The largest muscle of our body is in the ………………….. .
(a) arm
(b) face
(c) thigh
(d) None
Answer:
(c) thigh

State whether True or False. Correct the false statement and rewrite:

Question 1.
Saliva is mixed with food in the mouth.
Answer:
True.

Question 2.
Gastric juice makes food alkaline.
Answer:
False. Gastric juice makes food acidic.

Question 3.
Pancreas is the largest gland in the body.
Answer:
False. Liver is the largest gland in the body.

Question 4.
Food becomes acidic in stomach.
Answer:
True

Question 5.
Cardiac muscles are said to be voluntary muscles.
Answer:
False. Cardiac muscles are involuntary.

Question 6.
Muscles contribute 60% of the weight of a healthy adult human body.
Answer:
False. Muscles contribute almost 40% of the weight of a healthy adult human body.

Question 7.
There are about 30 muscles in the human face.
Answer:
True

Question 8.
Muscles in our arms and legs have involuntary muscles.
Answer:
False. Muscles in our arm and legs are voluntary muscles.

Question 9.
Functions of organs like stomach, intestine, heart are carried out by voluntary muscles.
Answer:
False. Functions of these organs are carried out by involuntary muscles.

Question 10.
Smooth muscles are involuntary muscles.
Answer:
True.

Question 11.
The digestive function of the liver is to produce bile.
Answer:
True.

Question 12.
The muscular tissue has the ability to contract or shorten.
Answer:
True.

Find a match for me.

Question 1.

Column A’	Column B’
1. Salivary gland	a. Making food acidic
2. Liver	b. Regulation of sugar level
3. Pancreas	c. Digestion of carbohydrates
4. Stomach	d. Digestion of protein, fats, carbohydrate

Answer:

Column A’	Column B’
1. Salivary gland	c. Digestion of carbohydrates
2. Liver	d. Digestion of protein, fats, carbohydrate
3. Pancreas	b. Regulation of sugar level
4. Stomach	a. Making food acidic

Question 2.

Column ‘A’	Column B’
1. Saliva	a. Gastric juice
2. Juice in mouth	b. Bile
3. Juice produced by stomach	c. Ptyalin
4. Juice stored by gall bladder	d. Lubricates food

Answer:

Column ‘A’	Column B’
1. Saliva	d. Lubricates food
2. Juice in mouth	c. Ptyalin
3. Juice produced by stomach	a. Gastric juice
4. Juice stored by gall bladder	b. Bile

Question 4.

Column ‘A’	Column B’
1. Cardiac muscle	a. Inside of organs like stomach
2. Skeletal muscle	b. Found in heart
3. Smooth muscle	c. Attached to bones

Answer:

Column ‘A’	Column B’
1. Cardiac muscle	b. Found in heart
2. Skeletal muscle	c. Attached to bones
3. Smooth muscle	a. Inside of organs like stomach

Find the odd man out:

Question 1.
Stomach, esophagus, liver, small intestine, rectum
Answer:
Liver which is a gland and others are parts of digestive tract.

Question 2.
Saliva, bile, pancreatic juice, gastric juice chyme
Answer:
Chyme, it is a liquid food others are digestive juices.

Name the following:

Question 1.
Gastric juices in stomach
Answer:
Hydrochloric acid, Pepsin, Mucus.

Question 2.
Juices secreted by liver
Answer:
Bile.

Question 3.
Pancreatic juices.
Answer:
Trypsin, Lipase, Amylase.

Question 4.
Salivary gland secretion.
Answer:
Saliva

Question 5.
Enzyme present in saliva.
Answer:
Ptyalin or Amylase.

Question 6.
Types of muscles.
Answer:
Skeletal, Cardiac and Smooth muscles.

Question 7.
Study of muscles.
Answer:
Myology

Give scientific reason:

Question 1.
Skeletal muscles give shape to our body.
Answer:

1. Skeletal muscles are voluntary muscles. The two ends of each of these muscles are attached to two different bones.
2. Muscles of the arms and legs are skeletal muscles.
3. They are responsible for holding the bones of the skeleton together and giving shape to our body.

Question 2.
The process of digestion begins in the mouth.
Answer:

1. The process of digestion begins with the function of the teeth.
2. There are 4 types of teeth – incisors, canines, pre-molar, and molar.
3. They are responsible for grinding the food.
4. Saliva present in the mouth mixes with the food and makes it soft.
5. An enzyme present in saliva called ptyalin amylase converts starch into maltose. Thus, the process of digestion begins in the mouth.

Question 3.
Metabolic processes are impossible without enzymes.
Answer:

1. Enzymes are substances secreted’ in the body of an organism which bring about specific chemical reactions.
2. Enzymes are specific type of proteins. They are most active at normal body temperature.
3. Digestion enzymes of the digestive system bring about changes in the food material.
4. Food is digested with the help of enzymes and converted into more soluble and simple form.

Write short notes on:

Question 1.
Voluntary muscles
Answer:

1. Working with our hands, walking, eating are functions that depend upon our will.
2. Muscles used in these actions are called voluntary muscles, e.g. skeletal muscles are voluntary muscles.

Question 2.
Involuntary muscles
Answer:

1. Various processes like breathing, blood circulation, digestion are vital function, essential for life.
2. They do not depend upon our will.
3. The muscles of organs which carry out these involuntary functions are called involuntary muscles.
4. Functions of organs like the stomach, intestine, heart are carried out in their own fixed manner by involuntary muscles, e.g. cardiac muscle present in heart, smooth muscles in lining of stomach, small intestine, blood vessel, uterus.

Question 3.
Muscle and its types
Answer:
There are three types of muscles in body

1. Skeletal Muscles
2. Cardiac Muscles
3. Smooth Muscles

Question 4.
Digestive glands
Answer:
The salivary glands, liver and pancreas are the digestive glands connected to the alimentary canal.
1. Salivary glands: (a) Saliva is produced in the salivary glands in the mouth cavity, located in front of the ears, below the tongue, (b) It is carried to the mouth via ducts, (c) It is mixed with food during the process of chewing.

2. Saliva: contains an enzyme called Ptyalin or salivary amylase. Ptyalin convdrtfe starch into a sugar called maltose.

3. Liver: (a) The liver is the largest gland in the body, (b) Main function is storage of glucose, (c) The digestive juice secreted by the liver is bile, (d) Bile is carried into small intestine, it mixes with food and helps in digestion of fats.

4. Pancreas: The pancreas secretes the pancreatic juice that contains various enzymes

• Trypsin → converts proteins into amino acids.
• Lipase → converts fats into fatty acids, glycerol
• Amylase → converts complex carbohydrate into simple sugar

Question 5.
Enzymes
Answer:
Enzymes are substances secreted in the body an organism which bring about specific chemical reactions.

1. Metabolic processes are impossible without enzymes.
2. Digestive exzymes of the digestive system bring about changes in the find material.
3. They break down the food into simple form.
4. They are a type of protein.
5. Saliva contain pytalin which converts starch into maltose.
   • Trypsin: Convert proteins into amino acids.
   • Lipase: Convert fats into fatty acid.
   • Amylase: Converts complex carbohydrates into simple sugar.

Question 6.
Draw the structure of the different layers of the tooth.
Answer:

Differentiate between:

Question 1.
Voluntary and Involuntary muscles.
Answer:

Voluntary muscle	Involuntary muscle
1. Voluntary muscle means you can control it consciously.	1. Involuntary muscles are controlled by your subconscious. You have no control over them.
2. Skeletal muscles are voluntary muscles.	2. Cardiac muscles and smooth muscles are involuntary muscles.
3. Muscles in our arms and legs are voluntary muscles.	3. Muscles in heart, stomach, blood vessel, intestine are involuntary muscles.

Question 2.
Skeletal muscle and Cardiac muscle.
Answer:

Skeletal muscle	Cardiac muscle
1. Skeletal muscles are voluntary muscles.	1. Cardiac muscles are involuntary muscles.
2. Muscles in our arms and legs are voluntary muscles.	2. Muscles in heart, stomach, blood vessel, intestine are involuntary muscles.
3. They hold bones of the skeleton together and gives shapes to our body.	3. They bring about contraction and relaxation of heart.

Answer the following:

Question 1.
What is meant by organ system?
Answer:

1. There are different structural organizational levels in living organism.
2. Cells → tissues → organ → organ system → organism
3. Different organs together form one organ system.

Question 2.
How are the bones in our body joined to each other?
Answer:
Skeleted muscles join two bones with the help of tendons.

Can you tell?

Answer the following questions:

Question 1.
What is the mutual relationship between muscles and bones?
Answer:

1. Muscles are firmly attached to bones by means of tendons.
2. When muscles contract there is movement at the joint and there is pull on tendon which in turn pull on the bones to which they are attached.

Question 2.
Are the muscles of the different organs in our body identical?
Answer:
No, muscles of the different organs are not identical, some are voluntary, some are involuntary.

Question 3.
How do muscles perform their functions?
Answer:

1. Muscles in our body always work in groups.
2. When some muscles contract other muscles of the same group relax.
3. This is how muscles help in proper performance of the various functions of own body.

Answer the following questions:

Question 1.
Which parts of our body are made up only of muscles?
Answer:
Tongue, heart, stomach, liver, pancreas, intestines are made up of only muscles.

Question 2.
What would happen if the cardiac muscles do not move?
Answer:

1. Cardiac muscles cause our heart to relax and contract continuously at a rate of about 70 times per minute.
2. These muscles bring about the contraction and relaxation (beating) of the heart.
3. If the cardiac muscles do not move, heart will stop beating, and will not pump blood to other parts of the body and person will die.

Question 3.
Food enters the stomach and the stomach muscles do not move.
Answer:

1. Smooth muscles are present in the lining of stomach.
2. Their movement is responsible for churning of food.
3. If the muscles do not move, food will not be digested.

Question 4.
During digestion does all the food that we have eaten get converted into useful nutritive substances?
Answer:

1. During digestion not all the food is converted into useful nutritive substance, only whatever nutrients we obtain by digestion of food gets absorbed into the blood in small intestine.
2. Undigested remains of the food enters the large intestine and thrown out of the body through the anus.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 8 Static Electricity Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 8 Static Electricity

Class 7 Science Chapter 8 Static Electricity Textbook Questions and Answers

1. Choose the correct option and fill in the blanks.
(always repulsion, always attraction, displacement of negative charge, displacement of positive charge, atom, molecule, steel, copper, plastic, inflated balloon, charged object, gold)

Question a.
There is ………….. between like charges.
Answer:
always repulsion

Question b.
…………. is responsible for generation of electric charge in an object.
Answer:
displacement of negative charge

Question c.
A lightning conductor is made of a ……………… strip.
Answer:
copper

Question d.
……………… does not get electrically charged easily by rubbing.
Answer:
Steel

Question e.
There is …………………. when opposite electric charges come near each other.
Answer:
always attraction

Question f.
A ……………… canbe detected with an electroscope.
Answer:
charged object

2. Explain why it is not safe to go out with an umbrella when there is heavy raine lightning or thunder.

Question a.
Explain why it is not safe to go out with an umbrella when there is heavy raine lightning or thunder.
Answer:
Large amount of charges get built up in the clouds in rainy and stormy weather.

1. Sometimes these charges are transferred to the earth in the form of a bolt of lightning.
2. Wire of umbrella is made up of metal and cloth is made up of synthetic material.
3. If lightning strikes, then umbrella catches it and there are chances of fire and it would be dangerous.
4. So it is not safe to go out with an umbrella when there is heavy rain.

3. Answer in your own words.

Question a.
How will you protect yourself from lightning?
Answer:

1. To protect from the lightning, we have to put lightning conductor on high rise buildings,
2. we should not stand under a tree in rainy and stormy weather.
3. We should not go out with an umbrella in heavy rain, lightning or thunder.

Question b.
How are charges generated?
Answer:

1. Friction causes a charge to develop, because on rubbing, some negative particles are transferred from one substance to the other and the later develops a negative charge.
2. The substance from which particles are removed lose negative charge and hence, it develops a positive charge.

Question c.
In the lightning conductor, what provision is made for spreading the electricity into the ground?
Answer:

1. The lightning conductor, consists of a long i copper strip with one end forked. This end is ‘ at the highest part of the building.
2. The other end of the strip is connected to a plate of cast iron.
3. A pit is dug in the ground, coal and salt are filled into the pit and the iron plate is placed upright in the pit.
4. There is also a provision for pouring water into it.
5. This helps to spread the electric charge quickly into the ground.

Question d.
Why do farmers stick an iron staff into the ground while working in the field in rainy conditions?
Answer:

1. Large amount of charges get built up in the clouds in rainy and stormy weather.
2. Sometimes these charges are transferred to the earth in the form of a bolt of lightning.
3. Due to iron staff, the charges will be conducted to the earth through iron metal and spread quickly into the ground.
4. This way farmers are saved from lighting strike.

Question e.
Why is lightning not seen every day during the rainy season?
Answer:

1. When air and clouds rub against each other in the sky the upper part of some clouds becomes positively charged and the lower side become negatively charged.
2. When this negative charge at the bottom of the cloud becomes much larger than the charge on the ground, it starts flowing towards the ground in stages, but this doesn’t happen every day. So lightning is not seen every day during the rainy season.

4. What are the characteristics of a static electric charge?

Question a.
What are the characteristics of a static electric charge?
Answer:
Following are the characteristics of a static electric charge.

1. The electric charge generated by friction is called frictional electricity. This charge is produced only at the place of friction, hence it is called static electricity.
2. It remains on the object for a short duration.
3. The charges of static electricity are absorbed in moist air.
4. An electrically charged object attracts another object which has no electric charge.
5. Like charges repel each other.
6. Unlike charges attract each other.
7. Repulsion is the sure test of the existence of a static charge.

5. What is the damage caused by lightning? How will you ereate awareness to prevent it?

Question a.
What is the damage caused by lightning? How will you ereate awareness to prevent it?
Answer:
Due to lightning great damage can occur.

1. It may cause fire.
2. Person on whom lightning strikes may die also.
3. It causes more temperature than sun.

Awareness to prevent it:

1. Guide the people to install lightning conductor on tall buildings.
2. Do not stand on open ground, below a tree, or on a high location during the thunder storms.
3. Do not use plugged in electrical appliances.
4. Do not stand near an electric pole, telephone pole or a tower.
5. Stay in pucca house made of brick and cement.
6. Stand on only wood, a plastic sheet or sack of jute.

Project:

Question a.
Make an electroscope yourself by using a thin aluminium foil and check which substances become electrically charged.

Class 7 Science Chapter 8 Static Electricity Important Questions and Answers

1. Choose the correct option and fill in the blanks.
(always repulsion, always attraction, displacement of negative charge, displacement of positive charge, atom, molecule, steel, copper, plastic, inflated balloon, charged object, gold)

Question 1.
named the electric charges as positive charge and negative charge.
Answer:
Benjamin Franklin

Question 2.
Each atom contains a stationary charge and moving charges.
Answer:
positive, negative

Question 3.
Each atom is electrically
Answer:
neutral

Question 4.
Amber is called in the Greek language.
Answer:
electron

Question 5.
The charges of electricity are absorbed in moist air.
Answer:
static

Question 6.
Electrically charged objects uncharged objects.
Answer:
attract

Question 7.
is used as a test for identifying an electrically charged object.
Answer:
Repulsion

Question 8.
The property of amber to attract things was named electricity by in 1646 AD.
Answer:
Thomas Brown

Question 9.
The electric charge generated by stays only as long as the charged object is near to it.
Answer:
induction

Question 10.
A simple device is used to detect the electric charge on an object.
Answer:
gold leaf electroscope

Question 11.
Lightning is a form of
Answer:
electric charge

Question 12.
The gas protects us from the harmful ultra violet rays coming from the sun.
Answer:
ozone

Question 13.
The is a device used for protection from a lightning strike.
Answer:
lightning conductor

Question 14.
Due to the energy of the lightning, the oxygen in the air is converted into
Answer:
ozone

2. Match the columns:

Question a.

Column ‘A’	Column ‘B’
1. Like charges	a. gold leaf electroscope
2. Unlike charges	b. lightning conductor
3. Copper strip	c. attraction
4. Gold leaves.	d. repulsion

Answer:

Column ‘A’	Column ‘B’
1. Like charges	d. repulsion
2. Unlike charges	c. attraction
3. Copper strip	b. lightning conductor
4. Gold leaves.	a. gold leaf electroscope

Say whether true or false, correct and rewrite the false statement:

Question 1.
Charges cannot be transferred from one body to another.
Answer:
False. Charges can be transferred from one body to another

Question 2.
The word ‘electricity.’ came from the word ‘Elektron’.
Answer:
True

Question 3.
When an inflated balloon is rubbed on silk, it develops a charge.
Answer:
True

Question 4.
An ebonite rod rubbed on woollen cloth develops a positive charge.
Answer:
False. An ebonite rod rubbed on woollen cloth develops a negative charge

Question 5.
A glass rod rubbed on woollen cloth develops a negative charge.
Answer:
False. A glass rod rubbed on woollen cloth develops a positive charge

Question 6.
If the leaves of the electroscope spread only a little, the charge on them is less.
Answer:
True

Question 7.
An atom may have either a positive or a negative charge.
Answer:
False. An atom does not have any charge

Question 8.
When two substances are rubbed on each other, like charges are developed on each.
Answer:
False. When two substances are rubbed on each other unlike charges are developed on each

Question 9.
High rise buildings have lightning conductors.
Answer:
True

Question 10.
It is dangerous to stand under a tree in rainy and stormy weather.
Answer:
True

Give scientific reasons:

Question 1.
Ordinarily, an atom does not have any charge.
Answer:

1. Every atom contains smaller particles with either positive or negative charge.
2. As the number of positively and negatively charged particles in an atom is equal, they neutralize each other.
3. As a result the atom has no charge.

Question 2.
Charge cannot be developed on a copper rod.
Answer:
Charge cannot be developed on a copper rod because only certain pairs of substances give rise to electric charge, on rubbing.

Question 3.
High rise buildings have lightning conductors.
Answer:

1. High rise buildings are prone to lightning strikes during the monsoon.
2. When lightning strikes, a tremendous electric charge is transferred to the earth, which may damage the tall buildings.
3. To prevent this, high rise buildings have a forked metal rod, called a lightning conductor fitted on the top of the building.
4. The lower end of this rod is buried inside the earth.
5. If lightening strikes, the electric charge passes through this conductor and goes in to the earth. In this way the building is saved from damage.

Question 4.
It is dangerous to stand under a tree in rainy and stormy weather.
Answer:

1. Large amount of charges get built up in the clouds in rainy and storming weather.
2. Sometimes these charges are transferred to the earth in the form of a bolt of lightning.
3. Generally lightning strikes tall buildings and trees. If lightning strikes a tree then either the tree may fall or it may catch fire.
4. In both cases this would be dangerous for anyone standing under the tree, hence it is dangerous to stand under a tree in rainy and stormy weather.

Question 5.
Repulsion is a test used for identifying an electrically charged object.
Answer:

1. When a charged object is brought near a neutral object, it gets attracted when two oppositely charged objects are brought close, they get attracted. Therefore, attraction is not a test.
2. But when two like charges are brought close only then repulsion takes place.
3. Therefore, repulsion is the sure test for identifying an electrically charged object.

Question 6.
Mustard seeds when shaken vigorously in a glass bottle stick to the sides of the bottle.
Answer:
When seeds are shaken they get electrically charged and therefore they stick to the neutral walls of the glass.

Answer the following:

Question 1.
Why is the charge developed due to friction called static electric charge?
Answer:
The charge developed due to friction is called 1 static electric charge because the charge remains still on the object.

Question 2.
Why does the charge developed by induction disappear quickly?
Answer:
The charge developed by induction disappears quickly because it is very weak.

Question 3.
Why do the leaves of a gold leaf electroscope fly apart when a charged body touches its disc?
Answer:
The leaves of a gold leaf electroscope fly apart when a charged body touches its disc because like charges develop on both the leaves and hence they repel each other.

Draw a neat labelled diagram of Gold leaf electroscope and describe it.

Answer:

1. This is a simple device to detect the electric charge on object.
2. It consists of a copper rod which has a metal disc at the upper end and two thin gold leaves at the other.
3. The rod is placed in a bottle so that the disc is above the bottle.
4. When an uncharged object is taken near the disc, the leaves remain closed.
5. When a charged object is taken near the disc, both the leaves are charged by the same electric charge, and repel each other.
6. When we touch the disc with our hand, the leaves collapse because the charge in the leaves goes into the earth through our body, and the leaves get discharged.

Use your brainpower:

Question 1.
Do all the objects get charged by rubbing?
Answer:
No. Only certain pairs of substances get charged on rubbing.

Question 2.
Why does a charged balloon stick to a wall?
Answer:
A charged balloon stick to a wall because there is always attraction between a charged object and an uncharged object.

Question 3.
Can we use leaves of some other metal instead of gold, in the electroscope? Which properties must that metal have?
Answer:
We can use other metals than gold in gold leaf electroscope.

1. Only thing is that metal should be malleable and good conductor of electricity.
2. But the best is gold only because we can make extremely thin leaves of gold so even very small charge also can be detected.

Question 4.
What kind of damage is caused by a lightning strike?
Answer:
Due to lightning strike, great damage can occur. It may cause forest fire and burn down things. Person on whom lightning strikes may die. It causes more temperature than sun.

Question 5.
What measures will you take to prevent the damage caused by lightning?
Answer:
Following measures can be taken to prevent the damage caused by lightning:

1. Always put lightning conductor on tall buildings.
2. Do not stand on open ground, below a tree or near the electric or telephone pole during rain/ thunder storms.
3. Do not lean on wired fences.
4. Do not use plugged in electrical appliances.
5. Do not swim during thunder storms.
6. Stay in a pucca house with lightning conductor fitted on it.

Question 6.
Why is the upper end of the lighting conductor pointed?
Answer:

1. The pointed end makes it possible to increase the electric field near the point. The electric field set up at pointed end is high.
2. If the discharge of cloud occurs it would be easily passed through the lightening conductor to the ground and damage to the building is averted.

Question 7.
Why is coal and salt added to the pit in the ground?
Answer:
Coal and salt is filled in the pit and also there is a provision for pouring water into it. This helps to spread electric charge quickly into ground and prevent damage.

Observe the given diagram and answer the questions given.

Question a.
Name the phenomenon happening in the diagram and define it
Answer:
Phenomenon happening is static electricity.
When certain objects are rubbed against each other, they produce an electric charge on their surface at the place of friction. This is due to electrons which remain for a short time. This is called static electricity.

Question b.
What do you observe in “b” and “c” part of the diagram?
Answer:
In ‘b’, we observe attraction between the charged balloon and the uncharged aluminium ball. In ‘c’, we observe that the charge has been transferred to the aluminium ball and due to the same (like) charge, repulsion is observed.

Balbharti Maharashtra State Board Class 7 English Solutions Chapter 4.2 Unke Munke Timpetoo Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 English Solutions Chapter 4.2 Unke Munke Timpetoo

Class 7 English Chapter 4.2 Unke Munke Timpetoo Textbook Questions and Answers

1. Make adjectives from the following.

Question a.
harm
Answer:
harmful / harmless

Question b.
fear
Answer:
fearless/fearful/fearsome

Question c.
question
Answer:
questionable

Question d.
continue
Answer:
continuous

Question e.
thought
Answer:
thoughtful/ thoughtless

Question f.
courage
Answer:
courageous

Question g.
believe
Answer:
believable

Question h.
wish
Answer:
wishful

2. Choose the correct alternative.

Question a.
Rohan desperately wished for ………….. .
i. a pair of shoes
ii. a warm pullover
iii. a good friend
iv. a table-tennis set
Answer:
iv. a table-tennis set

Question b.
Rohan and Muk entered the garden at midnight ……………. .
i. to frighten Mrs. Groover
ii. to chant around the banyan tree
iii. to steal some fruits
iv. to look for a table-tennis set
Answer:
ii. to chant around the banyan tree

Question c.
Rohan had finished ……………… rounds of the tree before Mrs. Groover discovered him.
i. seventeen
ii. six
iii. eleven
iv. twelve
Answer:
iii. eleven

Question d.
The table-tennis set was gifted by
i. Mrs. Groover
ii. Rohan’s parents
iii. Muk
iv. Timpetoo
Answer:
i. Mrs. Groover

Question e.
The Principal turned out to be a very …………… lady.
i. poor and simple
ii. proud and rich
iii. kind and understanding
iv. sad and lonely
Answer:
kind and understanding

3. The story has a very heart-warming and touching end. Now try to change the end of the story to make it sound.

Question 1.
(i) very funny
(ii) full of horror and mystery.
Answer:
Mrs. Groover continued to look at me with a strange look in her eyes which frightened me. I asked her whether she believed in ‘Unke, Munke, Timpetoo’. She suddenly gave out a shriek and started moving towards me with hands outstretched. I was so scared that my feet did not move nor any words came out from my mouth. She had a savage look on her face. I felt that there was something more to Mrs. Groover, no wonder she was staying alone with an evil looking dog. Somehow. I managed to run away from Mrs. Groover. The next day I came to know that Mrs. Groover never stayed in that house.

Mrs. Groover continued to look at me with a strange look in her eyes. It looked as if she was judging me. I asked her, whether she believed in ‘Unke, Munke, Timpetoo’. She said, she did but she was trying to control her laughter. I wondered what had happened to her. She laughed till tears started rolling down her cheeks. She then took me into her house and played some music as I sat listening. The singer used the same chant ‘Unke Munke Timpetoo’. Hearing the chart, I too started laughing and both of us had a hearty laugh and we started humming the song along with the words ‘Unke Munke Timpetoo’, which actually meant nothing.

4. ‘Unke, Munke, Timpetoo.

I wish, my wish is coming true.’
Try to compose two other funny magical chants that have rhyming lines.

5. Language study.

Question a.
Prefix and suffix : A letter or group of letters added to the front of a word to change Its meaning and make a new word is called a prefix.
Examples:

1. un + tie → untie
2. non + stop → non-stop
3. dis + like → dislike
4. super + man → superman
5. inter + national → international

Answer:
Prefix (before the root word)
e.g.

1. un + tie = untie
2. non + stop = nonstop
3. dis + like = dislike
4. super + man = superman
5. inter + national = international

Question b.
Find at least 5 words with prefixes and identify the prefix in each word. A letter or group of letters added at the end of a word to make another word is called a suffix.
Examples:

1. teach + er → teacher
2. act + or → actor
3. child + hood → childhood
4. friend + ship →b friendship
5. king + dom → kIngdom
6. use + ful → useful
7. frequent + ly → frequently
8. act + ion → action
9. star + ry → starry

Answer:
Suffix (after the root word)
e.g.

1. teach + er = teacher
2. act + or = actor
3. child + hood = childhood
4. friend + ship = friendship
5. king + dom = kingdom
6. use + ful = useful
7. frequent + ly = frequently
8. act + ion = action
9. star + ry = starry

Question c.
Find 5 examples of words with the following suffixes from the lessons you have studied so far, or from other sources:

1. -ship
2. -less
3. -ness
4. -ly
5. -ful
6. -able

Answer:
suffixes:

1. hard + ship = hardship
2. home + less = homeless
3. happy + ly = happily
4. clever + ness = cleverness
5. soft + ly = softly
6. reason + able = reasonable

Class 7 English Chapter 4.2 Unke Munke Timpetoo Additional Important Questions and Answers

1. Answer the following questions.

Question 1.
Find the sentences in which the author and his friend claim that they do not believe in magic. What do their actions show?
Answer:
The sentences which claim that the author and his friends do not believe in magic are:

1. I don’t say I believe in it but my cousin said it works.
2. And there is no harm in trying.
3. Why seventeen times and why at midnight?
4. I thought it was all nonsense.

Their actions show, that though they say that they do not believe in the chanting and magic, yet they decided to try it out, convincing themselves that it did not matter just to try.

Question 2.
(i) If you hear about something that fulfils your wishes, would you try it?
(ii) Do you think that the author is brave?
Answer:
(i) Yes, If I hear about something that fulfils my wishes, I would surely try it while trying to convince myself that there is no harm in trying.
(ii) Yes, I think the author is brave because he dared to go out at midnight to chant around the banyan tree to get his wish fulfilled knowing very well that the banyan tree belonged to his Ex-Principal who was very strict.

Question 3.
How do we know that Muk was frightened?
Answer:
We know that Muk was frightened because as soon as he heard Mrs. Groover’s voice saying that she would let her ferocious dog loose on them, he started climbing up the tree.

Question 4.
What opinion do you form of Mrs. Groover from the way she treats the boys?
Answer:
According to me, Mrs. Groover is an able administrator and disciplinarian outside but from the inside, she seems to be a kind-hearted, sensitive and understanding person. She did not jump to conclusions. She patiently listened to the boys and allowed Rohan to complete the seventeen rounds around the banyan tree to fulfill his wish.

Question 5.
Did the author really rejoice over his shoes and pullover?
Answer:
No, the author did not really rejoice over his shoes and pullover. He pretended to be happy so as not to hurt the feelings of his parents.

Reading Skills, Vocabulary and Grammar.

Simple Factual Questions:
Question 1.
Complete the following sentences.

1. Mrs. Groover’s garden had …………… .
2. Rinkoo Lai of class X was …………… .
3. “Come on, let us go and wish for my …………… .
4. There was a banyan tree, its aerial roots swaying in the …………… .

Answer:

1. a banyan tree
2. a bully
3. table tennis set
4. gentle breeze of the night.

Complex Factual Questions.

Question 1.
Who was Muk?
Answer:
Muk was Rohan’s best firend.

Question 2.
Who was Mrs. Groover?
Answer:
Mrs. Groover was the Ex-Principal of the school Rohan studies in.

Question 3.
Where was the banyan tree located?
Answer:
The banyan tree was located in Mrs. Groover’s garden which was in Rohan’s neighborhood.

Question 4.
How did Rohan and Muk enter Mrs. Groover’s house?
Answer:
Roshan and Muk entered Mrs. Groover’s house by climbing the wall and jumping down.

Vocabulary.

Question 1.
Pick out a compound word from the extract.
Answer:
neighborhood

Question 2.
Pick out two words so as to get its opposite after adding a prefix. Write both words.
Answer:

1. true × untrue
2. done × undone
3. harm × unharm

Question 3.
Give noun forms of:

1. mocking
2. true
3. suppose
4. enter
5. silent

Answer:

1. mockery
2. Truth
3. Supposition
4. entry/ entrance
5. silence

Question 4.
Pick out four adverbs from the passage.
Answer:

1. thoughtfully
2. badly
3. along
4. carefully

Question 5.
Express differently – ten minutes to twelve
Answer:
Eleven fifty.

Grammar.

Question 1.
I could not think of anything else. (Add a question tag)
Answer:
I could not think of anything else, could I?

Question 2.
One look from her piercing, pale, green eyes was enough to silence bullies. (Pick out the adjectives)
Answer:
one, piercing, pale, green.

Personal Response:

Question 1.
Do you believe in magic? Why?
Answer:
No, I do not believe in magic. I do not believe in magic because it is not proven by science.

Read the following passage and do the activities.

Simple Factual Questions:

Question 1.
Say whether true or false.

1. A ferocious dog ran after Rohan and Muk.
2. Mrs. Groover allowed Rohan to finish his rounds.
3. Mrs. Groover bend down to unleash, the dog.
4. Muk bodly faced the situation when the dog barked.

Answer:

1. False
2. True
3. True
4. False.

Question 2.
List the qualities of Mrs. Groover

Mrs. Groovers qualities
(i) …………………	(ii) …………………	(iii) …………………	(iv) …………………

Answer:

1. able administrator
2. empathetic
3. compassionate
4. loving and caring

Complex Factual Questions.

Question 1.
Why did Mrs. Groover threaten to unleash the dog?
Answer:
The barking of the dog awakened Mrs. Groover at night and in the darkness. She did not know who was there in the garden. Hence she asked who was there or else threatened to unleash the dog.

Question 2.
What was Rohan’s fear?
Answer:
Rohan’s fear was that Mrs. Groover might not believe him.

Vocabulary.

Give one word for the following.

1. Stop continuous progress
2. Say something indistinctly and quietly
3. feel or show great joy
4. set free

Answer:

1. interrupt
2. mumble
3. rejoice
4. unleash

Grammar.

Question 1.
State the tense in the following sentences.

1. I told her everything
2. I will explain if you let me.
3. I had never received such a big parcel.

Answer:

1. simple past tense
2. Simple future tense
3. Past perfect.

Question 2.
Form nouns.

1. ferocious
2. believe
3. open
4. softly

Answer:

1. ferocity
2. belief
3. opening
4. softness

Personal Response.

Question 1.
“and while leaving, would you mind using the front gate?” why do you think Mrs. Groover said that?
Answer:
Mrs. Groover being compassionate, understood the young boy’s heart. She knew that they had jumped into her compound. At midnight, as she wanted them to be safe, she was actually suggesting that they use the front gate.

Question 2.
“I swore that I would never return.” who said this and why.
Answer:
This was said by Rohan out of fear and frustration having gone through an unexpected turn of event in the middle of the night.

Question 3.
What is referred to as the ‘great moment’?
Answer:
To a little boy, opening gifts that he receives is a great moment. As it was Rohan’s birthday, he refers to unwrapping of the gifts he received.

Question 4.
Who had send the big parcel?
Answer:
The big parcel was from Unke, Munke, Timpetoo.

Read the following passage and do the activities.

Simple Factual Questions:

Question 1.
A few qualities have been listed below. Write suitable qualities under their names.

1. disciplinarian
2. friendly
3. committed
4. supportive
5. good runner
6. caring
7. loving
8. compassionate
9. eager
10. gratitude
11. nervous

Answer:

Mrs. Groover	Rohan	Muk
disciplinarian	good runner	friendly
caring	eager	committed
compassionate	gratitude	supportive
	nervous	loving

Question 2.
Complete the following.

1. I removed the colorful gift wrapping and found
2. I wondered if Mrs. Groover was responsible
3. She smiled and she looked so different,

Answer:

1. a table tennis set
2. for the surprise
3. almost human

Complex Factual Questions.

Question 1.
Why did Rohan whisper “wow!”?
Answer:
Rohan whispered ‘wow!” because when he opened the colourful gift wrapping, he found a table tennis set which he was greatly longing for. Also he was too thriled or and surprised to . say anything else.

Vocabulary.

Question 1.
Form Noun

1. remove
2. wonder
3. perfect
4. quickly

Answer:

1. removal
2. wonderment
3. perfection
4. quickness

Question 2.
Give adverbs form of:

1. imagine
2. increase
3. open
4. scare

Answer:

1. imaginatively
2. increasingly
3. openly
4. scarily

Grammar.

Question 1.
Muk and I went to see Mrs. Groover quite often. Not only because she made the best tea and cookies. We went because we liked her. (Rewrite using not only… but also)
Answer:
Muk and I went to see Mrs. Groover quite often not only because she made the best tea and cookies but also because we liked her.

Question 2.
I removed the strings impatiently. (Pick out the adverb from the given sentence)
Answer:
impatiently

Personal Response.

Question 1.
Do you think Mrs. Groover was responsible for the surprise? Why?
Answer:
Little Rohan longed to get a table tennies set as gift for his birthday and decided to run around a banyan tree in Mrs. Groover’s garden chanting “Unke Munke Timpetoo” seventeen times at 12 midnight. Understanding the child’s mind and seeing him take so much trouble, she decided to make him happy by gifting a fabulous table tennis set, through not brand new.

Question 2.
Why did Rohan and Muk visit Mrs. Groover often?
Answer:
After the initial nervousness and hesitation, Rohan found out that Mrs. Groover also believed in Unke, Munke, Timpetoo. They saw the soft human side of their Ex. Principal and started loving her. She too welcomed them with good tea and cookies. Hence they visited her often.

Question 3.
Did the surprise gift really come from Unke, Munke, Timpetoo? In your opinion, who must have sent the gift?
Answer:
No, the surprise gift did not come from Unke, Munke, Timpetoo. I am sure the surprise gift was sent by Mrs. Groover.

Question 4.
What is ‘Unke, Munke, Timpetoo’ – a charm or an act of friendliness?
Answer:
‘Unke, Munke, Timpetoo’ is an act of friendliness. We must remember that an act of friendliness is an act of godliness. It keeps alive the humanity in us which is very necessary to make this world a happy one.

Language Study.

Question 1.
Affixes: An affix is a letter or series of letters added to the root (main) word that can change its meaning. Affixes can take the form of a prefix or a suffix.
Answer:
(a) Examples of prefixes:

• trans + port = transport
• tri + angle = triangle
• uni + lateral = unilateral
• anti + biotic = antibiotic
• en + courage = encourage
• fore + head = forehead
• dis + appear = disappear
• extra + ordinary = extraordinary
• mid + way = midway
• hyper + active = hyperactive
• micro + scope = microscope
• post + pone = postpone
• ex + President = ex-President
• thermo + meter = thermometer
• super + star = superstar

(b) Some more suffixes:

• fashion + able = fashionable
• play + ful = playful
• slow + ly = slowly
• meaning + less = meaningless
• close + ness = closeness
• mad + ly = madly
• effort + less = effortless
• colour + less = colourless
• sad + ness = sadness
• owner + ship = ownership
• love + able = lovable
• beauty + ful = beautiful
• workman + ship = workmanship
• port + able = portable
• help + ful = helpful
• month + ly = monthly
• quick + ly = quickly

(Add more to this list…)

Do as directed:

Question 1.
Why seventeen times and why at midnight? (Identify the kind of sentence)
Answer:
Interrogative sentence

Question 2.
Don’t ask me. (Add a question tag)
Answer:
Don’t ask me, will you?

Question 3.
Forget it. (Add a question tag)
Answer:
Forget it, won’t you? / will you?

Question 4.
The aerial roots were swaying in the breeze. (Separate the Subject and Predicate)
Answer:
Subject – The aerial roots
Predicate – were swaying in the breeze.

Question 5.
Muk was climbing the tree. (Identify whether theverbisTransitiveor Intransitive)
Answer:
was climbing – Transitive verb.

Question 6.
Add one of these prefixes to the words below: (un-, re-, dis-)

1. Mother will ………….. (wrap) the gift.
2. My dad had to ………….. (connect) the light.
3. Jane had to ………….. (do) her homework.
4. Mohan ………….. (likes) eating leafy vegetables.
5. The knot on the rope is hard to ………….. (tie).

Answer:

1. unwrap
2. disconnect
3. redo
4. dislikes
5. untie

Question 7.
Write a single word with the prefix ‘un-‘ or ‘dis-‘ to complete each sentence.

1. My brother always ………….. (does not agree) with me.
2. The answer to your question is ………….. (not known).
3. My mother told me not to be ………….. (not honest).
4. I thought I had seen him but he seems to have ………….. (not appear).
5. I was ………….. (not happy) at being scolded.

Answer:

1. disagrees
2. unknown
3. dishonest
4. disappeared
5. unhappy

Question 8.
Put the words in the brackets in the appropriate form. (Use a prefix or a suffix)

1. He is acting in a very ………….. way. (child)
2. She looked ………….. She started to cry. (happy)
3. The team that he supported was able to win the ………….. (champion)
4. There were only a ………….. of people at the match, (hand)
5. I think you should ………….. your decision. (consider)
6. He wants to be a ………….. when he grows up. (politics)

Answer:

1. childish
2. unhappy
3. championship
4. handful
5. reconsider
6. politician

Question 9.
Make adjectives from the following:

1. nonsense
2. secret
3. knowledge
4. poet
5. city
6. village
7. humanity

Answer:

1. nonsensical
2. secretive
3. knowledgeable
4. poetical
5. urban
6. rural
7. humane

Unke Munke Timpetoo Summary in English

This story ‘Unke Munke Timpetoo’ revolves round a young boy Rohan, whose birthday. Rohan’s birthday was soon approaching. He wished to have a table tennis set, which he knew his parents would not be able to afford. He tells his wish to his best friend Muk, who tells him that if he really wished for the set, then he would have to go seventeen times around a banyan tree, at midnight chanting ‘Unke Munke Timpetoo’. At first he was scared but decides to try his luck around the only banyan tree which belonged to his Ex-Principal Mrs. Groover.

A day before his birthday he, along with his friend goes to the banyan tree. Rohan nearly completes his round when Mrs. Groover comes out and Rohan explains to her what he was doing and why. The next day along with his birthday gifts, he gets the gift he wished for. Only it was not brand new. He did not mind it at all. He wonders who could have sent him the table tennis set. He decides to ask Mrs. Groover but does not have the courage. He then asked if she believed in the chant ‘Unke Munke Timpetoo’ to which she said yes. Rohan, Muk and Mrs. Groover became the best of friends.

Introduction:

This story ‘Unke Munke Timpetoo’ is written by Sigrun Srivastava. She is an Indian author of German origin. She has written over 25 books for children of all ages.

Glossary

1. fantastic (adj) – fanciful, extraordinary
2. bully (n) – a person who is cruel to others especially those who are weaker or have less power
3. aerial (adj) – positioned high up in the air
4. ferocious (adj) – fierce
5. fabulous (adj) – marvelous, wonderful
6. vanish (v) – to become invisible, disappear
7. stutter (v) – to stammer

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 15 Materials We Use Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 15 Materials We Use

Class 7 Science Chapter 15 Materials We Use Textbook Questions and Answers

1. Fill appropriate terms in the blanks:
(white cement, soap, detergent, wearing of bones, tooth decay, hard, soft, portiand, fatty acid)

Question a.
The substance that helps water to remove dirt from the surface of material is called …………… .
Answer:
soap

Question b.
Fluoride is used in toothpaste to prevent …………… .
Answer:
tooth decay

Question c.
Soap is a salt of …………… and sodium hydroxide.
Answer:
fatty acid

Question d.
Synthetic detergents can be used in …………… water as well.
Answer:
hard

Question e.
For construction purposes …………… Cement is the most commonly used cement.
Answer:
white cement

2. Write answers to the following questions. 

Question a.
How does the use of a detergent help to clean soiled clothes?
Answer:

1. A molecule of a detergent holds on to a water molecule at one end and an oil molecule at the other.
2. As a result the molecules of oil mix with the water.
3. This is how detergent acts on our soiled clothes. So detergent removes any oil or dirt sticking on to our clothes.
4. Due to the property of holding on to both oil and water, soap water spreads easily on many types of surfaces.
5. This property of spreading on a surface is called surface activity.
6. Detergents are surface active.
7. One effect of surface activity is lather formation.

Question b.
How will you check with the help of soap powder whether water is hard?
Answer:

1. In the hard water, (of a well or a tube-well), soap does not give lather but forms a scum.
2. As a result, soap loses its cleansing property. So with help of soap we will come to know that it is a hard water.

Question c.
What are the important ingredients of a tooth paste and what is the function of each?
Answer:

1. The important ingredients of a toothpaste are calcium carbonate and calcium hydrogen phosphate.
2. They remove the dirt on teeth. These ingredients also polish the teeth.
3. A certain proportion of fluoride in the tooth paste helps prevent tooth decay.
4. It is essential for the enamel covering of teeth.

Question d.
What are the ingredients of cement?
Answer:

1. Cement is a dry, greenish grey powder with fine particles.
2. It is made from silica (sand), alumina (aluminium oxide), lime, iron oxide and magnesia (magnesium oxide).

Question e.
What will happen if cement is not used in making concrete?
Answer:

1. In making concrete strong, the ingredients cement, water, sand and gravel should usually be mixed in the ratio of 1 : 2 : 3 : 0.5 to achieve maximum strength.
2. If enough cement is not used then the concrete will eventually fall apart, as cement is used as a binding agent.

Question f.
Make a list of detergents, that you use. Answer: There are two types of detergents that we use, (a) Natural (b) Man-made detergents.

1. Natural detergents are soap nut (ritha) soap pod (shikekai).
2. Man-made detergents are soap, hard soaps, soft soaps.
3. Synthetic detergents have taken the place of soap.
   • Detergents are commonly available as powders or concentrated solution.
   • Detergents are for laundry, washing clothes and cleaning dishes.
4. Alkaline detergents used for hard surface cleaning.

Question g.
What should be expected from a detergent for delicate garments?
Answer:

1. Detergents should not be strong, they may spoil the texture, colour of delicate garments.
2. Now a days many detergents are available especially for woollen, delicate clothes.
3. They should not contain bleach, phosphorous which will harm delicate clothes.

Question h.
What is meant by surface activity? Name three chemicals responsible for the surface activity of various detergents.
Answer:

1. Due to the property of holding on to both oil and water, soap water spreads easily on many types of surfaces.
2. The property of a substance of spreading on a surface is called surface activity and the substance is called surfactant.
3. Detergents are surface active.
4. They increase the spreading and wetting ability of water by reducing its surface tension.
5. Chemicals responsible for the surface activity of various detergents is phenol, Aprotinin.

3. What are the similarities and differences between:

Question a.
Natural detergents and Man-made detergents
Answer:

Natural detergents	Man-made detergents
1. Soap nut (ritha) and soap pod (shikekai) are the natural detergents.	1. Soap is man-made detergent soft soap and hard soap.
2. Natural detergents do not have harmful effect on human skin or on silk or woollen clothes.	2. Soap has effect on skin and cloth because it has chemicals in it.
3. Soap nut, soap pod contain a chemical saponin.	3. Soap has acid in it, soap is sodium and potassium salt of fatty acids.
4. It is naturally available.	4. It is man made using chemicals and oil.

Question b.
Soap and Synthetic detergents
Answer:

Soap	Synthetic detergents
1. Soap is man-made detergent, it is in use since ancient times.	1. Synthetic detergent have taken the place of soap.
2. Soap loses its cleansing property in hard water it does not give lather.	2. Synthetic detergent can be used in hard water also.
3. Soap was prepared by using animal fat and wood ash.	3. Synthetic detergent are obtained by subjecting fats, kerosene to various chemical processes.
4. Variety of soaps are available, soft soap for bathing, hard soap for washing, cleaning.	4. Variety of synthetic detergents are available – Ariel, Surf Excel, etc.

Question c.
Bath soap and Soap for washing clothes
Answer:

Bath soap	Soap for washing clothes
1. Soft soap is used for bathing.	1. Hard soap is used for washing clothes.
2. Soft soap is potassium salt is fatty acids.	2. Hard soap is sodium salt of fatty acid.
3. Soft soap dissolves more easily readily in water.	3. Hard soap do not dissolve easily in water.
4. Now a days many perfumes, moisturizes are mixed to make it more attractive and useful.	4. In this type of soap now a days germicides, anti foaming agents are mixed to make it more useful.

Question d.
Modern cement and Ancient cement
Answer:

Modem cement	Ancient cement
1. Cement manufactured from 60% lime, silica 25% and alumina 5%. the rest is iron oxide and gypsum.	1. Romans used to make aqueous cement by mixing volcanic ash in moistened lime. It was very durable.
2. It is the most commonly used cement for Construction work.	2. It is Roman cement volcanic ash prevent cracks from spreading.
3. It is called Portland Cement.	3. It is called Aqueous Cement.

4. Explain why –

Question a.
Soap cannot be used in hard water.
Answer:

1. In the hard water of a well or a tube well, soap does not give lather but forms a scum.
2. As a result soap loses its cleansing property. So soap cannot be used in hard water.

Question b.
Oil does not mix in water. However, oil and water become homogenous if a sufficient quantity of detergent is added.
Answer:

1. A molecule of a detergent holds on to a water molecule at one end and an oil molecule at the other.
2. As a result the molecules of oil mix with the water, and we will see that the water and oil have become homogenous and the colour of the mixture appears milky.

Question c.
Synthetic detergents are superior to soap.
Answer:

1. Soap is a man-made detergent which has been in use since ancient times.
2. It was prepared by using animal fat and wood ash. In hard water, soap does not give lather, it loses its cleansing property.
3. So we can not use soap in hard water. Now synthetic detergents have taken the place of soap.
4. They can be used in hard water as well
5. Synthetic detergents have many more advanced properties like they are added with perfumes, conditioner for fabric, etc.

Question d.
Often coloured spots are formed on clothes during washing.
Answer:

1. Curry stains stick fast to the criss-crossing threads of the material of our clothes.
2. Curry contains turmeric a natural indicator which turns red in a basic solution.
3. Soaps are sodium salts of fatty acids and are basic in nature.
4. While washing the clothes, turmeric reacts with soap solution and turns red forming red spots on the clothes.
5. But the spots disappear after washing the clothes with plenty of water.

Question e.
Tobacco masheri should not be used for cleaning teeth.
Answer:

1. Masheri is the smokeless form of tobacco. It is tobacco, containing teeth cleaning powder
2. It contains tobacco leaves.
3. Tobacco contains toxic and Carcinogenic chemicals which can cause cancer, oral cancer, mouth and throat cancer, gum disease, tooth decay.
4. Its use can cause abnormal delivery in pregnant women.

Project:

Question 1.
Visit a cement factory. See how cement is prepared and discuss the process.

Question 2.
Write a conversation based on cement houses, mud-houses and wattle-and-daub houses.

Class 7 Science Chapter 15 Materials We Use Important Questions and Answers

Fill in the blanks:

Question 1.
The principal ingredients of a toothpaste are ………………. and ………………. which remove the dirt on the teeth.
Answer:
Calcium carbonate, calcium hydrogen phosphate

Question 2.
………………. in the toothpaste helps prevent tooth decay.
Answer:
Fluoride

Question 3.
The property of a substance of spreading on a surface is called ………………. .
Answer:
surface activity

Question 4.
………………. and ………………. are the natural detergent in common use.
Answer:
Soap nut, Soap pod

Question 5.
Soap nut and soap pod contain a chemical named ………………. .
Answer:
Saponin

Question 6.
………………. is a man-made detergent.
Answer:
Soap

Question 7.
………………. is used for washing clothes.
Answer:
Hard soap

Question 8.
………………. is used for bathing.
Answer:
Soft soap

Question 9.
Hard soap is ………………. salt of fatty acids.
Answer:
Sodium

Question 10.
Soft soap is ………………. salt of fatty acids.
Answer:
Potassium

Name the following:

Question 1.
A substance which is spread on a given surface and used for cleaning.
Answer:
Surfactant

Question 2.
A chemical contained in soap nut and pod.
Answer:
Saponin

Question 3.
An element which helps prevent tooth decay which is used in toothpastes.
Answer:
Fluoride

Question 4.
The latin word which means detergent.
Answer:
Detergere

Question 5.
A cement used for construction purpose.
Answer:
Portland cement

Question 6.
A mixture of cement, water, sand and gravel.
Answer:
Concrete

Question 7.
A natural detergent.
Answer:
Soap nut

Choose the correct option:

Question 1.
Which one of these material grows on an animal
(cotton, rubber, wood, wool)
Answer:
Wool

Question 2.
Which of these is man-made?
(oranges, apples, plastic bags, tomatoes)
Answer:
Plastic bags

Question 3.
The statue is made from marble, marble is a ………….. material.
(weak, elastic, man-made, natural)
Answer:
Natural

Question 4.
Toy Duck is made from plastic. Plastic is a ………….. material.
(natural, man-made, raw, precious)
Answer:
Man-made

Question 5.
Which of these materials is natural?
(Nylon, Rock, Plastic, Polythene)
Answer:
Rock

Question 6.
Which one of these is a natural material?
(Lemonade, Cola, Water, Ice cream)
Answer:
Water

Question 7.
The toy plane made from wood. Wood is a ………….. material.
(man-made, natural, weak)
Answer:
Natural

Question 8.
Which one of these materials is natural?
(Nylon, cotton, polythene, polyesters)
Answer:
Cotton

Match the following:

Question 1.

Column ’A’	Column ’B’
1. Fluoride	a. Man-made detergent
2. Soap nut	b. Sodium salt of fatty acid
3. Soap	c. Man-made material
4. Cotton	d. Prevents tooth decay
5. Nylon	e. Potassium salt of fatty acid.
6. Hard soap	f. Natural detergent
7. Calcium carbonate	g. Natural material
8. Soft soap	h. Main ingredients of toothpaste

Answer:

Column ’A’	Column ’B’
1. Fluoride	d. Prevents tooth decay
2. Soap nut	f. Natural detergent
3. Soap	a. Man-made detergent
4. Cotton	g. Natural material
5. Nylon	c. Man-made material
6. Hard soap	b. Sodium salt of fatty acid
7. Calcium carbonate	h. Main ingredients of toothpaste
8. Soft soap	e. Potassium salt of fatty acid.

Find out:

Answer the following questions:

Question 1.
What is the source of the fluoride in a tooth paste or tooth powder?
Answer:
A naturally occurring mineral found in tooth paste and drinking water. Sodium Fluoride (NaF) is the source of fluoride in toothpaste.

Question 2.
Note down all the information given on a tooth powder/toothpaste container or carton and discuss.
Answer:
1. The carton shows the name of the company and name of toothpaste and its contains all the ingredients present in toothpaste.

2. Licence No. of company, Regd. Trade Mark of Colgate Palmolive Co-manufactured by Colgate-Palmolive (India) Ltd. Licenced user of Trade Mark made in India. Tooth paste contains 1000 ppm max of available fluoride when packed.

3. Ingredients: Calcium carbonate, sorbitol, sodium lauryl sulphate, silica, sodium silicate flavour, sodium monoflouro phosphate, sodium bicarbonate, benzyl alcohol.

4. Direction for use: Brush thoroughly atleast twice a day.
5. Children under 6 years of age should have adult supervision and use only appropriate amount.

Question 3.
Now a days why are the roads made of concrete?
Answer:

1. Concrete is prepared by mixing cement, limestone, sand, gravel, and water. It is solid, more durable and strong.
2. There is no erosion for many years and roads are smoother. So the roads are made of concrete.

Question 4.
What causes the hardness of water?
Answer:

1. Hardness is a measure of amount of dissolved salts in water.
2. It is caused by dissolved salts like carbonates, chlorides mostly of calcium and magnesium
3. Presence of these makes washing of clothes by soap difficult.
4. Hard water is water that has high mineral content.
5. Hard water is formed when water percolates through deposits of limestone and chalk.

Can you tell?

Answer the following questions:

Question 1.
Which substances were used earlier for cleaning teeth?
Answer:
In olden times neem twigs, coal powder ash, tooth powder, salt, pomegranate rind, were used for cleaning teeth.

Question 2.
What do we use today to clean our teeth?
Answer:
Now a days we use variety of toothpastes and tooth powders to clean our teeth.

Question 3.
What do we use for cleansing our body?
Answer:
Soap, many liquid body wash are also used to clean our body.

Question 4.
What are the materials used for construction?
Answer:
Metals, wood, stone, cement, concrete, timber, bricks, metal sheet, soil, Earth, marble, aluminium, iron, steel, bamboo, glass, plastic.
Concrete: is a wet mixture of sand, gravel, cement, and water used to create building foundations, footpaths or roads.

Question 5.
Which of the houses seen in the pictures here have a strong structure? Why?

Answer:
The houses made from stone, bricks, and cement and concrete have a strong structure.

Write short notes on or Explain:

Question 1.
Natural detergent
Answer:

1. It is naturally available soap nut (ritha) and soap pod (shikekai) are the natural detergents in common use.
2. They contain a chemical named saponin.
3. Soap nut and soap pod do not have any harmful effect on human skin or on silk, woollen threads, and cloth.

Question 2.
Man-made detergents
Answer:

1. Detergent which is made by processing naturally available material, soap is a man-made detergent which has been in use since ancient times.
2. In those days soap was prepared by using animal fat and wood ash.
3. Therefore two types of soap (a) Hard Soap is used for washing clothes. It is a sodium salt of fatty acids, (b) Softsoap is used for bathing. It is a potassium salt of fatty acids.
4. It does not cause irritation of the skin.
5. But we can’t use soap in hard water because soap does not give lather but forms a scum. So, soap loses its cleansing property so now synthetic detergent have taken the place of soap.
6. Synthetic detergents are obtained by subjecting these raw materials (fats and kerosene) to a variety of chemical processes. These can be used in hard water as well.

Question 3.
Soap
Answer:
Two types of soap are:
1. Hard soap is used for washing clothes. It is a sodium salt of fatty acids.
2. (a) Softsoap is used for bathing. It is a potassium salt of fatty acids, (b) It does not cause irritation of the skin, (c) But we can’t use soap in hard water because soap does not give lather but forms a scum, (d) So, soap loses its cleansing property so now synthetic detergents have taken place of soap, (e) Synthetic detergents are obtained by subjecting these raw materials (fats and kerosene) to a variety of chemical processes, (f) These can be used in hard water as well.

Question 4.
Concrete
Answer:

1. Concrete is prepared by mixing cement, water, sand and gravel.
2. For making a strong and leak proof slab certain substances are mixed in concrete.
3. Now a days, roads are made of concrete because they are very durable, strong and smooth.

Question 5.
Surface activity
Answer:

1. Soap molecule has the property of holding on to both oil and water soap water spreads easily on many types of surfaces.
2. The property of a substance of spreading on a surface is called surface activity and the substance is said to be a surfactant.
3. Detergents are surface-active. One effect of surface activity is lather formation.

Question 6.
Explain the method of preparation of soap.
Answer:
Material required for preparation soap are 15 g sodium hydroxide, 60 ml coconut oil, 15 g salt, perfume, a glass rod, beaker, tripod, wire gauze, burner, water mould etc.
Procedure:

1. Take 60 ml of coconut oil in a beaker.
2. Dissolve 15 g sodium hydroxide in 50 ml water. Mix the sodium hydroxide solution in the oil slowly, while stirring with a glass rod.
3. Heat the mixture, and boil it for 10 – 12 minutes, stirring it all the while.
4. Take care that the mixture does not boil over while heating.
5. Dissolve 15 g salt in 200 ml water, pour this solution into the above mixture and stir.
6. The soap formed by the chemical reaction now floats on the water. After some time, it becomes thick.
7. Now separate the thick soap and add the perfume to it, shape the bar of soap using the mould.
8. In this process, fat and alkali combine to form salts of fatty acids.
9. Chemically, soap is a sodium or potassium salt 4 of fatty acids.

Balbharti Maharashtra State Board Class 7 English Solutions Chapter 1.2 Odd One In Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 English Solutions Chapter 1.2 Odd One In

Class 7 English Chapter 1.2 Odd One In Textbook Questions and Answers

1. Read aloud the conversations in the story turn by turn.

Question 1.
Read aloud the conversations in the story turn by turn.

2. Write about Malti and Rima using the following points:

Question 1.
Write about Malti and Rima using the following points:

Use details from the story and your own imagination when you write the above descriptions.
Answer:

Points		Rima
Appearance	Simple, oily hair, long skirt	Stylish.
Studies	Studious, intelligent, scored well in studies. She was good at Maths.	She was also good in studies.
Singing	She had a melodious and well-trained voice. She wins the first prize in the Inter­house singing competition.	She was also good at singing and wins the first prize in her own category in the Inter­house singing competition.
Attitude Towards Others	Helpful and respectful. Ready to learn from others and improve.	Rude, arrogant, unkind behaviour. She didn’t like to be corrected.
Weak Points	Her English was poor.	She was weak in Hindi. She was jealous of others and thought others to be inferior to her.

3. Imagine you are Malti. Write any one event in the story from Malti’s point of view.

Question 1.
Imagine you are Malti. Write any one event in the story from Malti’s point of view.
Answer:
Yesterday, I was absent from school. I decided to ask Rima and other classmates about the lessons taught by teachers. As soon as I uttered “I wanted to aks you about English assignment”, Rima and her friends burst out laughing. At first I didn’t understand why they were laughing. Then Rima started mocking at me, repeating the word ‘aks’.

Other girls giggled and looked at me with contempt. I felt very bad but I requested Rima to teach me English as she was good in English and its pronunciation. But she told me rudely that as I belong to the countryside, I am incapable of speaking proper English. There was a lump in my throat as I could not bear this humiliation. I wanted to retort but I couldn’t find the right words. I burst into tears and decided to run away from there.

4. How do you behave with your classmates? Write about your attitude and behaviour in the appropriate column:
(Some actions: Ask others for help, Refuse help, Judge others by their appearance, Judge others by their accent)

Question 1.
How do you behave with your classmates? Write about your attitude and behaviour in the appropriate column:
(Some actions: Ask others for help, Refuse help, Judge others by their appearance, Judge others by their accent)

Answer:

Always	Sometimes	Never
I help others.	I am sometimes grumpy towards my friends.	I am never judgemental.
I share my tiffin with my friends.	I enquire about the health of a sick classmate.	I never use harsh words.
I always respect others.	I sometimes visit NGO’s to volunteer.	I never misbehave in class.

Note: Students do the exercise based on their own individual behaviour.

5. Talk about: (a) your strengths (b) your weaknesses (c) the changes that you would like lo see in yourself (3 each).

Question a.
Your strengths:
Answer:
My biggest strength is my willingness to learn and improve myself. I am very polite and humble. I am also a good listener due to which I make friends very easily.

Question b.
Your weaknesses:
Answer:
I am lazy when it comes to doing homework.
I have a phobia of speaking in front of a large group. This has developed into stage fright. I also can’t stop eating once I start. This makes me fall sick very often.

Question c.
The changes that you would like to see in yourself:
Answer:
I would like to get rid of my laziness. I want to start cultivating the habit of reading to improve my language. I would like to participate confidently in competitions. And lastly I want to control my diet for a healthy living.

6. Discuss: Is it necessary to develop a good accent? Why? What efforts can you take to improve your pronunciation? With your teacher’s help, find out how to use online dictionaries for the purpose.

Question 1.
Discuss: Is it necessary to develop a good accent? Why? What efforts can you take to improve your pronunciation? With your teacher’s help, find out how to use online dictionaries for the purpose.
Answer:
Yes, it is extremely necessary to develop a good accent because it aids in communication. A proper accent is important to understand and be understood. I can refer a dictionary that provides pronunciation key. I can also listen to news channels such as BBC that helps us to speak English the way the natives do. Besides, no matter what the language, avoiding the influence of mother tongue can help improve pronunciation.

7. list all the adverbs that end with ‘-ly’ from the passage.

Question 1.
list all the adverbs that end with ‘-ly’ from the passage.
Answer:

1. quietly
2. rudely
3. cattily
4. uncharitably
5. sadly
6. snidely
7. abundantly
8. readily
9. cheerfully
10. mercilessly
11. particularly
12. roundly
13. badly
14. stubbornly

8. Language Study:

Question 1.
Types of nouns: You know that a noun is a word used as the name of a person, place or thing. The names given to particular persons, places, animals etc. are proper nouns and the rest are common nouns. For example, ‘Ria’ is a proper noun, because it is the name of a particular person. But, ‘girl’ Is a common noun, as It is not the name of a particular person. ‘Ahmednagar’ Is a proper noun, because it is the name of a particular place. ‘Town’ Is a common noun, because it is not the name of a particular place.
Answer:

Write at least 5 common nouns and 5 proper nouns each. Proper nouns are always written with a capital letter at the beginning. Can you think of proper nouns that include two or more words? How are they written? Find at least ten such nouns.
Examples: Seva Hospital, The Times of India.

Class 7 English Chapter 1.2 Odd One In Additional Important Questions and Answers

Answer the following questions.

Question 1.
Complete the web.
Answer:
i.

ii.

Question 2.
How did Rima and her friends try to offend Malti?
Answer:
Rima and her friends tried to. offend Malti by asking her about the oil on her hair and her long skirt.

Question 3.
Guess what Malti was about to say when the teacher entered?
Answer:
When the teacher entered, Malti was about to probably justify why she wore long skirt or oiled her hair.

Question 4.
What did Rima and her gang decide to do during the Inter-house singing competition? Did they succeed? Why?
Answer:
Rima and her gang decided to jeer when Malti sang but they did not succeed as there was such absolute silence that they did’not dare to do so. They were sure to get caught if they did

Question 5.
Why did Rima feel no joy even though she came first in her category?
Answer:
(Rima had thought that Malti must be a miserable singer and would lose in the singing competition but Malti won the first prize. Rima felt no joy even though she came first in her category as she was proved wrong and may be she even felt jealous of Malti.

Question 6.
Why did Rima walk off in a huff?
Answer:
Rima’s friends told her that she was rude to Malti. This shocked Rima as her own friends had turned against her. So, she walked off in a huff.

Question 7.
What would you have done if you would have been in Malti’s place?
Answer:
If I would have been in Malti’s place, I would have done exactly what Malti did. I would have let my work and performance speak for myself. I would have also tried to befriend Rima by helping her or praising her for her strengths.

Question 8.
Write a character sketch of Rima.
Answer:
Rima was a school-going girl who had her own clique of stylish girls. She was quick to judge people by their outward appearance. She was a bit of a snob who didn’t hesitate to comment on Malti’s oily hair. She had an envious nature as she wasn’t happy about Malti winning the first prize although she herself had also won the first prize in her own category. She thought herself to be far more superior as she was city-bred and could speak good English. She was too proud to accept her mistake when her friends pointed it out to her.

Question 9.
Discuss the meaning in the context of the story.
Answer:

1. befriended (v) – became friends
2. snob (n) – criticizing people coming from lower social class or are less education
3. forte (n) – something one is good at
4. belied (v) – failed to give a true impression or to tell lie
5. smart (adj) – intelligent, clever
6. confident (adj) – feeling or showing confidence in oneself or one’s abilities or qualities or being sure about ones abilities.
7. insufferable (adj) – intolerable

Reading Skills, Vocabulary and Grammar

Read the following passage and do the activities.

Simple Factual Questions:

Question 1.
Fill in the blanks:
i. “Any new girls in your class?” enquired her father …………. .
ii. “She can’t speak …………. English.
Answer:
i. Mr. Sen
ii. much

Question 2.
Say whether true or false and correct in case the statement is false.
Rima can’t speak much English.
Answer:
False. Malti can’t speak much English.

Complex Factual Questions:

Question 1.
How did Rima describe Malti to her father?
Answer:
Rima described to her father that Malti was a funny girl from a state at the other end of the country who could not speak much English. She also added that Malti came with oily hair and a bindi and spoke with a strange accent.

Question 2.
Do Rima and her parents share the same attitude?
Answer:
No, Rima and her parents do not share the same’attitude. The parents confront Rima with reality. We know that because Rima’s parents defend and praise Malti when Rima criticizes her.

Vocabulary:

Question 1.
Guess the meanings of the following words in the context of the story
Answer:

• settling in (v) – to arrange oneself comfortably in
• sniffed (v) – drew in air audibly to show dislike
• mimicked (v) – imitated the voice and behaviour
• grimaced (v) – made a twisted expression on face to express disgust.

Grammar:

Question 1.
Write at least 4 Proper nouns from the above passage.
Answer:

1. Rima
2. Mr. Sen
3. Malti
4. English

Question 2.
Write at least 4 Common nouns from the above passage.
Answer:

1. mother
2. day
3. girls
4. school

Personal Response:

Question 1.
Have you ever been a victim of bullying in your class? How did you tackle it?
Answer:
Yes, I have been a victim of bullying in my class due by a handful of bullies in the class. They used to call me ‘teacher’s pet’ and tease me. Initially I was annoyed. But with the help of my parents and teachers I began to help one of the weaker students who used to bully me. In the first semester his grade were raised and he became fan and strong supporter. Eventually the others also realized their mistakes and accepted me as a friend and took my help to improve.

Question 2.
How did Rima decide whether or not Malti was smart? What is your opinion?
Answer:
Rima decided Malti’s smartness by the way she dressed and spoke English. I do not think that we should judge someone’s smartness by their outward appearance. Besides, even if someone does not speak good English, it cap always be learnt and improved upon, and the person may be very good at some other language.

Question 3.
Do Rima and her parents share the same attitude? How do we know that?
Answer:
No, Rima and her parents do not share the same opinion. We know this from the conversation between Rima and her parents. The mother feels that Malti is a clever girl for she raised her hand to answer all questions in the class. When Rima said that Malti’s English is bad and she isn’t clever, her father pointed out to Rima that the same goes with her Hindi.

Read the following passage and do the activities.

Simple Factual Questions:

Question 1.
Complete the web with the names of Rina Clique friends.
Answer:

Complex Factual Questions:

Question 1.
Why was Rima sad and depressed at lunch time?
Answer:
Rima was sad and depressed at lunch time because she knew she had behaved badly with Malti but didn’t want to accept it. Besides her own friends had gone against her.

Question 2.
Which lines from the passage tell us that Malti was a very humble person?
Answer:
“I know my English is weak. Yours is good. Please, will you help me to improve it?” These lines tell us that Malti was very humble.

Vocabulary:

Question 1.
Give the antonyms of:
1. proud
2. mercilessly
Answer:
1. humble
2. mercifully, compassionately

Grammar:

Question 1.
Her own friends had turned against her.
(Separate the subject and predicate)
Answer:
Her own friends – subject
had turned against her – predicate.

Question 2.
Rima was shocked. (Transform into a question)
Answer:
Wasn’t Rima shocked?

Personal Response:

Question 1.
Is it necessary to accept one’s mistake? Why?
Answer:
Yes, it is very necessary for one to accept his mistake, because only when we accept our mistake will we make an attempt to improve ourselves. Besides, one must understand that we are all humans and are bound to make mistakes. What is important is to learn from the mistakes and not repeat them.

Language study:

Do as directed.

Question 1.
Write at least 5 common nouns and 5 proper nouns each.
Answer:

• Common nouns: parents, friends, table, participants, child, etc.
• Proper nouns: Rima, Malti, Saturday, English; Clare, etc.

Question 2.
Can you think of proper nouns that include two or more words? How are they written? Find at least ten such nouns.
Answer:
Proper nouns with two or more words have each word beginning with a capital letter except prepositions and articles.
(a) St. Peter’s Church (b) Marks & Spencer (c) The Retreat Resort (d) United Kingdom (e) Bank of Baroda (f) Big Bazaar (g) The United States of America (h) United Colours of Benetton (i) The Great Escape Water Park (j) Phoenix Market City Mall.

Question 3.
Match the meanings.

Column ‘A’	Column ‘B’
1. forte	a. to arrange oneself comfortably in a new place
2. belied	b. to transfer
3. befriended	c. to express contempt
4. settling in	d. fail to give a true impression of something
5. sniffed	e. intolerable
6. insufferable	f. become a friend when in need of help
	g. something one is good at

Answer:

Column ‘A’	Column ‘B’
1. forte	g. something one is good at
2. belied	d. fail to give a true impression of something
3. befriended	f. become a friend when in need of help
4. settling in	a. to arrange oneself comfortably in a new place
5. sniffed	c. to express contempt
6. insufferable	e. intolerable

Question 4.
Add a suffix to any 4 words from the lesson to make their noun forms.
Answer:

• improve – improvement
• quiet – quietness
• clear – clearance
• bright – brightness

Question 5.
Make sentences using phrases/idioms.
Answer:
Question i.
To help oneself
Answer:
She placed the bowl of dessert on the table and askeci the guests to help themselves.

Question ii.
To dote on someone
Answer:
My best friend’s mother dotes on her and buys her expensive clothes.

Question iii.
To be on the verge of something
Answer:
The differences between the two countries increased so much that they were on the verge of having a war.

Question iv.
To burst into tears
Answer:
When she saw her lost child after seven days, she burst into tears.

Question v.
To walk away in a huff
Answer:
When Hera’s friends started teasing her for her new hairstyle, she walked away in a huff.

Question 6.
Discuss the difference in the meaning of the following words:
Answer:

1. Smart – a clean, tidy, well-dressed person having quick-witted intelligence.
2. confident – a person who believes in oneself or one abilities and qualities.
3. snob – person who believes that his/her taste in a particular area is superior to those of other people.

Do as directed:

Question 1.
The teachers had liked the respectful, intelligent girl from the beginning.
(Pick out the adjectives and state their kind)
Answer:
respectful, intelligent – Adjectives of quality.

Question 2.
Malti sang beautifully.
(Pick out the verb and state whether it is transitive or intransitive)
Answer:
sang – Intransitive.

Question 3.
No one was surprised when Malti won the first prize.
(Pick out the conjunction)
Answer:
when – conjunction.

Question 4.
We put Rima into a good school to make her smart and confident.
(Pick out the preposition)
Answer:
into, to – preposition.

Question 5.
Malti answered ………………. .
(Fill in adverb of your choice to complete the sentence)
Answer:
softly, politely

Question 6.
She can’t speak much English.
(Add a question tag)
Answer:
She can’t speak much English, can she?

Question 7.
Malti looked offended but did not reply. (Replace the underlined conjunction with another conjunction without changing the meaning)
Answer:
Malti looked offended still yet did not reply.

Question 8.
Malti felt bad about their ………………….. .
(Fill in the blank with an abstract noun of your choice)
Answer:
Malti felt bad about their poverty.

Question 9.
This one does not seem smart at all.
(Change the number)
Answer:
These ones do not seem smart at all.

Question 10.
Rima did come first in her category.
(Pick out the adjective)
Answer:
first – adjective

Writing Skills:

Question 1.
Can you imagine what happened next in this story of Rima and Malti? Complete the story on your own.
The time gone by …………….
Answer:
Rima knew that she had behaved very badly. She was too proud to admit it – even to herself. Next day, after a sleepless night, Rima dragged herself to school. When she reached, her friends were already chatting with Malti. This upset her even more. Within a week or so, all her friends had befriended Malti and were all praises about her. But Rima thought otherwise.

She took it to be a wicked plan of Malti to isolate her from her friends. Rima who had always been a topper started losing confidence. This affected her performance in exams. She soon lost the affection of her teachers who thought she needed to change her rude behaviour. Rima’s health suffered and she fell sick very often. After a week’s absence from school, when she resumed, none of her friends asked her about her health.

When she asked for notes that she had missed, no one lent her the books. Rima approached the teacher and requested her to give her a week’s time to complete all the books. She also asked if she could get someone’s book to complete her notes.

The teacher send that Malti had already made notes for Rima with her permission. Rima completed all her books with Malti’s help. She was touched by this kind of gesture. She realised her mistake and apologized to Malti who embraced her. Both Rima and Malti became best of friends. Rima had learnt that beauty is skin deep.

Odd One In Summary in English

Introduction:

The lesson ‘Odd One In’ is an excerpt from the book of the same name by Tithi Tavora. Set against the backdrop of challenges encountered by a newcomer in school. The story highlights the importance of inner beauty as compared to outward appearance.

Paraphrase:

The story revolves around Rima, a city bred brat, who is quick to judge the newcomer, Malti, a countryside girl. Rima and her friends look down upon Malti for her simple looks and dressing sense. However, Malti proves her mettle to them over a period of time. Rima learns a lesson not to judge anyone by their outward appearance and be respectful to one and all. But does she really learn the lesson? Well, read the story to find more….

Glossary:

1. shrugged (v) – raised the shoulders slightly and briefly as a sign that one does not care or know about something.
2. grimaced (v) – made a twisted expression on the face to express disgust or pain or something hurting youth.
3. mimicked (v) – imitatedl the voice and behaviour
4. chorused (v) – said the same thing together
5. giggled (v) – laughed in a silly way
6. cattily (adv) – in a mean way
7. recounted (v) – narrated
8. uncharitably (adv) – in an unkind way
9. atrocious (adj) – bad
10. countered (v) – opposed
11. snidely (adv) – rudely and critically
12. abundantly (adv) – extremely
13. nimble (adj) – quick
14. clique (n) – a group of people who do not readily allow others to join
15. exaggerated (v) – altered; to make something larger than it is.
16. accent (n) – pronunciation
17. countrified (adj) – unsophisticated, simple
18. retort (v) – to reply in a short angry or witty manner
19. jeer (v) – make rude remarks a in a loud voice
20. horrid (adj) – horrible
21. roundly (adv) – completely
22. subdued (adj) – quiet and depressed