Prasanna

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 15 Life Processes in Living Organisms Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Science Solutions Chapter 15 Life Processes in Living Organisms

Class 9 Science Chapter 15 Life Processes in Living Organisms Textbook Questions and Answers

1. Match the pairs and explain.

Column ‘A’	Column ‘B’
(1) Growth of pollen tube towards ovules (2) Growth of shoot system (3) Growth of root system (4) Growth towards the water	(a) Gravitropic movement (b) Chemotropic movement (c) Phototropic movement (d) Growth-irrelevant movement (e) Hydrotropic movement

Answer:
(1 – b),
(2 – c),
(3 – a),
(4 – e).

2. Complete the paragraph.

The milk was on the stove. Rasika was engrossed in watching television. She smelled something burning. She ran towards the kitchen. The milk was boiling over. She held the vessel with her bare hands but, screaming, she let it go at once. This activity was controlled by ……………….. cells. Special ends of ……………….. in these cells collected the information, from where it was transferred to the ……………….. and then towards the terminal end of the ……………….. The chemicals produced at the terminal end passed through the minute space i.e. ………………. . In this way, ……………….. were conducted in the body and the process of ……………….. was completed by conducting the impulses from ……………….. to ………………

(Nerve, muscle cell, impulse, dendrite, synapse, axon, reflex action, cell body)
Answer:
nerve, dendrite, cell body, axon, synapse, impulses, reflex action, nerve, muscle cell.

3. Write notes on Root pressure, Transpiration, Nerve cell, Human brain, Reflex action

4. Name the hormones of the following endocrine glands and the function of each.
Pituitary, Thyroid, Adrenal, Thymus, Testis, Ovary.

Life Processes In Living Organisms Class 9 Question 1.
Pituitary:
Answer:

Hormone	Function
(i) Growth hormone	Stimulates growth of bones.
(ii) Adrenocorticotropic hormone	Stimulates adrenal gland.
(iii) Thyroid-stimulating hormone	Stimulates thyroid gland.
(iv) Prolactin	Stimulates milk production.
(v) Follicle-stimulating hormone	Controls growth of gonads.
(vi) Luteinizing hormone	Controls menstrual cycle and ovulation.
(vii) Oxytocin	Contracts uterus during parturition.
(viii) Antidiuretic hormone	Regulates water-level in the body.

Class 9 Science Chapter 15 Life Processes In Living Organisms Question 2.
Thyroid
Answer:

Hormone	Function
(i) Thyroxine	Controls growth of body and metabolic activities.
(ii) Calcitonin	Controls calcium metabolism and calcium level in blood.

Life Processes In Living Organisms Class 9 Exercise Question 3.
Adrenal
Answer:

Hormone	Function
(i) Adrenalin and nor-adrenalin	Controls behaviour during crisis and emotional situation.
(ii) Corticosteroid	Maintains balance of Na+ and K+ and stimulates metabolism.

9th Class Science Chapter 15 Life Processes In Living Organisms Exercise Question 4.
Thymus
Answer:

Hormone	Function
Thymosin	Control the cells which give rise to immunity.

Question 5.
Testis
Answer:

Hormone	Function
Testosterone	Stimulates growth of secondary sexual characteristics like beard, mustache, hoarse voice etc. in men.

Std 9 Science Chapter 15 Life Processes In Living Organisms Question 6.
Ovary
Answer:

Hormone	Function
(i) Oestrogen	Stimulates growth of the endometrium. Stimulates growth of secondary sexual characteristics in women.
(ii) Progesterone	Prepares the endometrium for conception and maintains pregnancy.

5. Draw and label the diagrams.
Human endocrine glands, Human brain, Nephron, Nerve cell, Human excretory system.

15. Life Processes In Living Organisms Question 1.
Human endocrine glands
Answer:

15 Life Processes In Living Organisms Question 2.
Human brain
Answer:

Life Processes In Living Organisms 9th Class Notes Question 3.
Nephron
Answer:

Life Processes In Living Organisms Class 9 Questions And Answers Question 4.
Nerve cell
Answer:

Life Processes In Living Organisms Class 9 Solutions Question 5.
Human excretory system
Answer:

6. Answer the following.

a. Explain chemical co-ordination in humans and give the names and functions of some hormones.
Answer:
Chemical co-ordination in humans :

• In humans chemical co-ordination is brought about with the help of certain chemical substances called hormones.
• Hormones are secreted by endocrine glands. These glands are also called ductless glands.
• These glands do not have any arrangement of their own to either store or carry their secretions. So, the hormones are directly released into the blood circulation.
• Though the endocrine glands are present at specific locations in our body, their secretions reach all parts of the body via the blood.
• Endocrine glands along with the nervous systems are responsible for control and co-ordination in our body.
  These two systems help each other to control and integrate the various activities of the body.
• A marked difference between these two systems is that nerve impulses are fast but short-lived whereas the actions of hormones are very slow but long-lasting.
• It is very important that hormones are secreted only in the required quantity and there is a special mechanism which controls the quantity and timing of hormone secretion.
• For example, whenever there is an increase in blood glucose level, certain cells in the pancreas get stimulated and as a response, they release a greater quantity of insulin, thus bringing down the sugar level to normal.

Hormone	Function
(1) Growth hormone	Stimulates growth of bones.
(2) Luteinizing hormone	Controls menstrual cycle and ovulation.
(3) Thyroxine	Controls growth of body and metabolic activities.
(4) Insulin	Stimulates liver to convert excess blood glucose to glycogen.
(5) Testosterone	Stimulates growth of secondary sexual characters like beard, mustache, hoarse voice, etc. in men.

Names and functions of some hormones:

b. Explain the difference between the excretory system of humans and plants.
Answer:

Excretory system of humans	Excretory system of plants
(i) In humans, the excretory system carries out the function of the removal of waste from the body.	(i) In plants, there is no special system or organ for excretion.
(ii) Waste substances are generally eliminated out of the body	(ii) Most of the waste substances are stored in the leaves, flowers, fruits and bark of the stem.
(iii) The excretory products are urea, uric acid, ammonia, etc.	(iii) The excretory products are gum, resin, latex of rubber, etc.

c. Explain co-ordination in plants with the help of suitable examples.
Answer:

• Plants do not have systems like the nervous system or muscular system.
• In plants, movements are mainly in the form of responses given to the stimuli.
• Plants show two types of movements – growth relevant movements and growth irrelevant movements.
• Movement or growth of any part of the plant in response to an external stimulus is called tropism or tropic movement.
• Examples of growth-relevant movements are :
• The shoot system of any plant responds to the light stimulus i.e., it grows towards the source of light. This is called phototropic movement.
• The root system of plants responds to stimuli like gravitation and water. These responses are called gravitropic movement and hydrotropic movement respectively.
• Movement shown by plants in response to specific chemicals is called chemotropic movement.
• For example, the growth of the pollen tube towards the ovule.
• Some specific movements of the plants do not lead to the plant growth.
• Such movements are called growth-irrelevant movements.
• As a response to changes in the surroundings, plant hormones bring about various movements in plants.
• Examples of growth irrelevant movements are closing of leaflets of Touch-me-not (Mimosa) plant on touch.
• In the plant called Venus fly trap, when an insect visits the flower like trap, the trap closes up and the trapped insect is digested by the plant.
• The lotus flower opens during day-time while that of the tuberose opens at night.
• In plants like Touch-me-not (Mimosa), movement also occurs at places other than where it has been touched.
• Hence, we can infer that the information about the touch must have been released within the plant from one place to another.
• Plants use electrochemical impulses for transfer of information from one place to another.
• Plant cells change their shape by increasing or decreasing the water content and thereby, bring about the movements of plants.

7. Explain in your own words with suitable examples.

a. What is meant by co-ordination?
Answer:

• Several different organ systems function in multicellular organisms.
• Their life goes on smoothly if there is co-ordination between different organ systems or organs and the stimuli in the surrounding.
• Depending upon this, we can say that systematic regulation of different processes can be called control and bringing about the different processes in the proper sequence is called co-ordination.
• If any activity in the body is to be completed successfully, proper co-ordination between different systems, and organs participating at different steps of that activity is necessary.
• If due to lack of co-ordination, there is confusion at any step, the activity may not get completed. There should be no randomness at any step.
• There should be proper co-ordination between internal activities of the body resulting from various factors like body temperature, water- level, enzyme-level, etc. or stimuli arising in the surrounding environment.
• Proper co-ordination between various systems of an organism helps to maintain a state of equilibrium called homeostasis which is necessary for the optimal efficiency of the body.

b. How does excretion occur in human beings?
Answer:

• Removal of wastes from the body is very important and it is the excretory system that carries out this function.
• The human excretory system consists of a pair of kidneys, a pair of ureters, the urinary bladder and the urethra. Urine is formed by the kidneys by separating the waste and unwanted excess substances from the blood.
• The functional unit of the kidney that performs the basic function of filtration is called a nephron. The urea produced in the liver comes into the blood.
• When the urea-containing blood comes into the glomerulus, it is filtered through capillaries and urea and other similar substances are separated from it.
• Water molecules and small molecules of some other substances can cross the semipermeable membrane of Bowman’s capsule.
• The solution accumulated in the cavity of Bowman’s capsule passes into the tubular part of the nephron. Here, molecules of water and some other useful substances are reabsorbed into the blood.
• Urine is formed from the remaining solution which is full of waste materials. The urine is carried by the ureters and stored in the urinary bladder. Afterwards, urine is given out through the urethra.

c. How is excretion in plants useful to human beings?
Answer:

• Plants give out oxygen during photosynthesis by diffusion which is useful to human beings for respiration.
• Some waste materials of plants for example, gum, resin, latex of rubber, etc. are useful to humans.

d. Describe the transportation system in plants.
Answer:

• Plants have two types of conducting tissues i.e., xylem which conducts water and phloem which conducts food.
• During transpiration, water is released into the atmosphere.
• As a result, water level is the epidermal layer of the leaf decreases.
• Water is brought up to the leaves through the xylem so as to compensate for the lost water.
• Transpiration helps in absorption of water and minerals and distribution to all parts of the plant whereas root pressure preforms the important role of pushing the water up at night time.
• The food produced by leaves is transported to each cell of the plant through phloem.
• When the food material like sucrose is transported towards a part of the plant through phloem, using ATP, the water concentration in that part decreases.
• As a result, water enters the cell by diffusion. The pressure on the cell wall increases due to increase in the cellular contents.
• Due to the increased pressure, food is pushed into the neighboring cells where the pressure is low.
• This process helps the phloem to transport the materials as per the need of the plant.

Class 9 Science Chapter 15 Life Processes in Living Organisms Intext Questions and Answers

Class 9 Science Chapter 15 Life Processes In Living Organisms Exercise  Question 1.
How do the digestive system and respiratory system work?
Answer:
(a) Digestive system:

• The digestive system is responsible for digestion of food. i.e. breaking down complex insoluble food into simpler soluble form.
• The digestive system is made up of alimentary canal and digestive glands.
• The alimentary canal is a long and muscular tube of varying diameter which extends from the mouth to the anus.
• The digestive glands associated with alimentary canal are salivary glands, gastric glands, liver and pancreas.
• The process of digestion includes various stages wherein the food passes through the different organs of the alimentary canal and there it is digested part by part with the help of various enzymes secreted from the digestive glands.
• After the food is digested, the important nutrients are absorbed into the blood and the undigested food and residue of digested food is removed out of the body through the anus.

(b) Respiratory system:

• Respiration is the process of release of energy from the assimilated food.
• The respiratory system consists of nose, pharynx, larynx, trachea, bronchi and lungs (alveoli).
• Oxygen enters our body through breathing.
• This oxygen is taken to the cells and with the help of oxygen, food is oxidized into the cells to release energy in the form of ATR
• During this process, carbon dioxide and water vapour are given out as by-products which are given out during breathing.

Thus, the digestive and respiratory systems work in co-ordination with each other to produce energy from food.

Life Processes In Living Organisms Exercise Question 2.
Previously you have performed the activity of observing a branch covered in a plastic bag. What did you observe in that activity?
Answer:

• When a branch is covered in a plastic bag, we observe that small droplets of water accumulate on the inner side of the plastic bag.
• This shows that leaves release water in the form of vapour through the stomata during transpiration. These vapours get condensed to form water droplets and accumulate inside the bag.

Life Process In Living Organism Exercise Question 3.
Which are the sensory organs of an organism? What is their function?
Answer:

• Sensory organs of an organism are eyes, ears, tongue, skin and nose.
• The eyes help the organism to perceive the sensation of light to see the objects around it.
• The ears help the organism to perceive the sensation of sound and also perceive the sensation of pressure.
• The tongue helps to perceive different tastes and also in chewing the food.
• The skin helps to perceive the sensation of touch, pain, pressure etc.
• Some insects also possess antennae for sensing the changes in the environment.

15 Life Processes In Living Organisms Class 9 Question 4.
Where are the gustatory and olfactory nerves to be found?
Answer:

• Gustatory nerves are concerned with sense of taste whereas olfactory nerves are concerned with the sense of smell.
• Gustatory nerves are found in the tongue from where they carry impulses to the gustatory cortex in the brain.
• Whereas the olfactory nerves are found in the nasal passage from where they carry impulses to the olfactory lobes in the brain.

Answer the following questions:

15.Life Processes In Living Organisms Question 1.
Why do we eat fruits and vegetables? Do the plants also need minerals like we do?
Answer:

• We eat fruits and vegetables to get nutrients like carbohydrates, vitamins, minerals and fibers. These nutrients are important for the proper functioning of the body .
• Plants too need minerals for their growth and development.

Life Processes In Living Organisms Class 9 Notes Question 2.
From where do plants get inorganic substances other than carbon dioxide and oxygen?
Answer:
Plants get inorganic substances like nitrogen, phosphorus, magnesium, manganese, sodium etc. from the soil. Soil is the nearest and richest source of these elements.

9th Std Science Chapter 15 Life Processes In Living Organisms Question 3.
At least a small quantity of garbage or waste is produced every day in each house. What will happen if you keep this garbage for many days in your house?
Answer:

• If we keep garbage for many days in our house, it will start decaying due to the growth of decomposers like fungi and bacteria.
• This will result in foul odour and will also lead to spread of diseases.

Life Processes In Living Organisms Exercise Class 9 Question 4.
Sometimes, while eating we bite our own finger or tongue by mistake.
Answer:

• Sometimes, while eating we over-fill our mouth causing the bite to misalign, thus we bite our own finger or tongue by mistake.
• If we are dehydrated, the muscles of the mouth and tongue do not function properly causing us to bite our own tongue.
• If we are distracted with other activities while eating, it can cause us to bite our tongue or finger.
• Thus, due to lack of co-ordination sometimes while eating, we bite our own finger or tongue by mistake.

9th Class Science 15 Chapter Life Processes In Living Organisms Question 5.
Sometimes, we choke while eating in a hurry.
Answer:

• There is an elastic flap at the starting of the wind-pipe called epiglottis which opens whenever we breathe in air and closes to prevent the entry of food into the respiratory system.
• While eating in hurry, due to lack of co-ordination, the epiglottis opens to take in air but food too enters in causing us to choke.

Life Processes In Living Organisms Class 9 Extra Questions Question 6.
An injury to the medulla oblongata can lead to death. Why?
Answer:

• The medulla oblongata controls involuntary activities like the beating of the heart, blood circulation, breathing etc.
• An injury to the medulla oblongata will stop these activities, leading to death.

Life Processes In Living Organisms Class 9 Maharashtra Board  Question 7.
You may have seen how a drunken person struggles to maintain his body balance. An excess of alcohol in the body causes one to lose control over it. Why does this happen? Find out the reason with help of the internet.
Answer:

• The cerebellum co-ordinates voluntary movements and maintains balance of the body.
• An excess of alcohol causes dysfunctioning of the cerebellum.
• It results in primary loss of co-ordinated movements and loss of balance.

9th Life Processes In Living Organisms 5 Question 8.
Why does this happen?

(a) Leaves of plants fall off in a particular season.
Answer:

• Plants lose water through their leaves by transpiration. So some plants shed their leaves in dry season to reduce transpiration and conserve water.
• In plants, the waste substances are stored in the vacuoles of leaf-cells which are then shed along with the leaves in a specific season.

(b) Fruits, flowers fall off after a certain period of time.
Answer:

• In plants, waste substances are stored in the vacuoles of fruits and flowers. So, they fall off after some time to excrete these wastes.
• Also, when fruits and flowers mature, the supply of nutrients to mature fruits and flowers is blocked. This causes abscission in that part of the plant leading to their detachment from the plant body and falling off.

(c) Substances like resin, gum, etc. are given out of the plant body.
Answer:

• Resin, gum etc. are the waste products of plants. They are given out after some time as a process of excretion in plants.
• Many plants, particularly, woody plants produce resin and gum in response to injury. These resin and gum act as bandage protecting the plants from invading insects and pathogens.

15 Life Processes In Living Organisms Exercise Question 9.
Which waste products are produced in our body through metabolic activities?
Answer:
The waste products formed in our body through metabolic activities are urea, uric acid, ammonia, carbon dioxide etc.

Life Processes In Living Organisms 9th Class Exercise Question 10.
As compared to the monsoons and winter a very small quantity of urine is produced in the summer season. Why is it so?
Answer:
In summer, we sweat more due to excess heat. So, the body tries to conserve water by reducing urine formation. This is to prevent dehydration.

Question 11.
In adults, the process of urination is under their control but not in infants. Why is it so?
Answer:

• In adults, the muscles of the bladder are under the voluntary control. So the process of urination is under control.
• In infants, the bladder muscles are not mature until about two years of age. So, the process of urination is not under control.

Answer the following questions:

Question 1.
Observe the following figures carefully.

Answer:
Observations:

• Figure ‘A’ shows chemotropic movement. Pollen tube grows towards the ovule in response to specific chemicals released by the ovule.
• Figure ‘B’ shows phototropic movement. Shoot grows towards the Sun in response to stimulus of light.
• Figure ‘C’ shows thigmotropic movement. Tendrils of climbers are sensitive to touth. When they come in contact with an object, they entwine around the object and cling to it.
• All the above movements are related to growth. Hence, they are called growth relevant movements.

Question 2.
Observe the pictures carefully and think about them.

Answer:

• Figure ‘A’ shows touch-me-not (Mimosa) plant. In this plant, the leaflets close in response to stimulus of touch.
• Figure ‘B’ shows Venus fly trap. In this plant, there is a trap that appears and smells like a flower and deceives the insect. When an insect visits that flower-like trap, the trap closes up and the trapped insect is digested by the plant,
• Figure ‘C’ shows lotus plant. The lotus flower opens during day-time.?
• Figure ‘D’ shows Balsam plant. In this plant, the ripened fruit dehisces (bursts open) at the right time to disperse the seeds.

Question 3.
As you watch the match being played on your school ground, you will see the control and co-ordination among the movements of the players. Make a list of all such different actions.
Answer:
In an inter-house basketball match, control and co-ordination is seen in dodging the ball, jumping, running, passing it to the team mates and dribbling the ball.

Question 4.
Observe the figure carefully and as per the numbers in that figure, answer the following questions.

(a) What is happening at 1 and 2?
Answer:
At 1 stimulus of heat is received by thermo-receptors in the skin. At 2, the hand is withdrawn instantly.

(b) Which nerve carried the impulse to the point marked 3? In which direction is it conducting the impulse?
Answer:
Sensory nerve carried the impulse to the point marked 3. The impulse is conducted from the skin towards the spinal cord.

(c) Which is the nerve shown by 4?
Answer:
The nerve shown by 4 is association neuron. It is present in the gray matter of the spinal cord. It receives the sensory impulse, interprets it and generates impulse.

(d) Which is the organ marked as 5?
Answer:
Spinal cord.

(e) At 6, which nerve is conducting the response impulse?
Answer:
Motor nerve.

(f) At 7, where has the impulse reached? What is its effect?
Answer:
At 7, the impulse has reached the muscles of the hand. As a result, the muscles contract and the hand is withdrawn instantly in response to the stimulus of heat.

Question 5.
Sketch and label:
Answer:

• Stimulus
• Hand is withdrawn
• Sensory neuron
• Association neuron
• Spinal cord
• Motor neuron
• Muscles

(6) Observe the figure and list down functions for ‘A’ and ‘B’

Answer:

Functions of Left Brain	Functions of right brain
(i) Analytical thinking	Holistic thinking
(ii) Logical thinking	Intuition
(iii) Language	Creativity
(iv) Science and Mathematics	Art and music

Answer the following questions:

Question 1.
Take a small plant like balsam or tuberose with its roots intact. Wash and clean its roots. As shown in the fig, keep it in the water containing a stain like safranin or eosin. Observe the stem and the veins of the leaves after 2-3 hours.

Answer:

• The stem and veins of the leaves appear pinkish in colour.
• Due to the root pressure generated, eosin solution is continuously pushed upward.
• As a result water reaches xylem and the water column is pushed forward.

Question 2.
Take a transverse section of the stem of a plant and observe the stained xylem under a compound microscope.
Answer:
The xylem elements appear pinkish as the eosin solution is conducted upwards through the xylem. From this we infer that the xylem is responsible for the conduction of water and minerals in the plant.

Question 3.
Observe your mother while she cuts the elephant’s foot (Amorphophallus) or arum leaves. Your hands may also begin to itch if you try to cut these leaves. Why does this happen? Try to find out. Ask your mother what she does to prevent the itching.
Answer:

• In some plants like elephant foot (Amorphophallus) or arum, waste materials are in the form of crystals of calcium oxalate. They are called raphides.
• As they are needle-shaped, they prickle and cause irritation of the skin leading to itching.
• This can be prevented by applying tartaric acid (tamarind) or citric acid (lemon) on the hands while cutting these vegetables as the acids dissolve the crystals of calcium oxalate.

Class 9 Science Chapter 15 Life Processes in Living Organisms Additional Important Questions and Answers

Choose and write the correct options.

Question 1.
The transport of food produced in leaves to each cell in the plant body is called …………………………… .
(a) Transpiration
(b) Root pressure
(c) Translocation
(d) Ascent of sap
Answer:
(c) translocation

Question 2.
Kidneys filter blood about ……………………………. times every day.
(a) 100
(b) 200
(c) 300
(d) 400
Answer:
(d) 400

Question 3.
About ……………………………. of blood is sent through the dialysis machine at one time.
(a) 500 ml
(b) 5 l
(c) 200 ml
(d) 400 ml
Answer:
(a) 500 ml

Question 4.
The movement of plant towards the source of light is called ……………………………. movement.
(a) chemotropic
(b) hydrotropic
(c) phototropic
(d) gravitropic
Answer:
(c) phototropic

Question 5.
The movement of root system towards stimulus of gravity is called ……………………………. movement.
(a) phototropic
(b) gravitropic
(c) hydrotropic
(d) chemotropic
Answer:
(b) gravitropic

Question 6.
The movement of root system towards stimulus of water is called ……………………………. movement.
(a) Phototropic
(b) Gravitropic
(c) Hydrotropic
(d) Chemiotropic
Answer:
(c) hydrotropic

Question 7.
Hormone ……………………………. helps in stem elongation.
(a) Auxin
(b) Gibberellin
(c) Cytokinin
(d) Abscisic acid
Answer:
(b) Gibberellin

Question 8.
Hormone ……………………………. helps in cell division.
(a) Auxin
(b) Gibberellin
(c) Cytokinin
(d) Abscisic acid
Answer:
(c) Cytokinin

Question 9.
The hormone ……………………………. is effective in prevention and retardation of growth, leaf wilting, etc.
(a) Auxin
(b) Cytokinin
(c) Gibberellin
(d) Abscisic acid
Answer:
(d) Abscisic acid

Question 10.
……………………………. neurons conduct impulses from the sensory organs to the brain and the spinal cord,
(a) Sensory
(b) Motor
(c) Association
(d) All of these
Answer:
(a) Sensory

Question 11.
The brain of an adult human weighs about …………………………… .
(a) 500 – 600 grams
(b) 2 – 3 kilograms
(c) 1300 -1400 grams
(d) 1500 -1600 grams
Answer:
(c) 1300 – 1400 grams

Question 12.
……………………………. is the largest part of the brain.
(a) Cerebrum
(b) Cerebellum
(c) Medulla oblongata
(d) Spinal cord
Answer:
(a) Cerebrum

Question 13.
There are two triangular swollen structure called ……………………………. on the upper side of the medulla oblongata.
(a) Ventricles
(b) Meninges
(c) Pyramids
(d) Pons
Answer:
(c) Pyramids

Question 14.
Control of voluntary movements is done by …………………………… .
(a) Cerebrum
(b) Cerebellum
(c) Medulla oblongala
(d) Spinal cord
Answer:
(a) Cerebrum

Question 15.
Co-ordination of voluntary movements is done by …………………………… .
(a) cerebrum
(b) cerebellum
(c) medulla oblongata
(d) spinal cord
Answer:
(b) cerebellum

Question 16.
Control of involuntary activities like the beating of the heart, blood circulation, breathing etc. are controlled by …………………………… .
(a) Spinal cord
(b) Cerebrum
(c) Cerebellum
(d) Medulla oblongata
Answer:
(d) Medulla oblongata

Question 17.
The function of cerebrum is to …………………………… .
(a) control of voluntary movements
(b) co-ordination of voluntary movements
(c) control of involuntary activities
(d) maintaining the body balance
Answer:
(a) control of voluntary movements

Question 18.
The function of cerebellum is …………………………… .
(a) to control of voluntary movements
(b) to maintain the body balance
(c) to control of involuntary activities
(d) to co-ordinate of voluntary movements
Answer:
(b) to maintain the body balance

Question 19.
Hormone ……………………………. stimulates the liver to convert excess blood glucose into glycogen.
(a) Glucagon
(b) insulin
(c) Somatostatin
(d) Pancreatic polypeptide
Answer:
(a) Glucagon

Question 20.
Hormone ……………………………. controls behaviour during crisis and emotional situation.
(a) Thyroxine
(b) Parathormone
(c) Adrenalin and Nor adrenalin
(d) Somatostatin
Answer:
(c) Adrenalin and Nor adrenalin

Question 21.
……………………………. controls menstrual cycle and ovulation.
(a) Prolactin
(b) Oxytocin
(c) Luteinizing hormone
(d) Progesterone
Answer:
(c) Luteinizing hormone

Question 22.
……………………………. stimulates growth of secondary sexual characteristics in men.
(a) Thymosin
(b) Testosterone
(c) Oestrogen
(d) Thyroxine
Answer:
(b) Testosterone

Question 23.
……………………………. occurs through stomata.
(a) Translocation
(b) Perspiration
(c) Transpiration
(d) Conduction
Answer:
(c) Transpiration

Question 24.
……………………………. performs the important role of pushing the water up during the night time.
(a) Translocation
(b) Root pressure
(c) Transpiration pull
(d) None of these
Answer:
(b) Root pressure

Question 25.
In plants, gaseous substances are given out by …………………………….
(a) Root pressure
(b) Osmosis
(c) Diffusion
(d) Translocation
Answer:
(c) diffusion

Question 26.
Each kidney has approximately ……………………………. nephrons.
(a) 1 lakh
(b) 10,000
(c) 10 lakh
(d) 50 lakh
Answer:
(c) 10 lakh

Question 27.
Insulin is secreted by the ……………………………. of the pancreas.
(a) Alpha cells
(b) Beta cells
(c) Delta cells
(d) F cells
Answer:
(b) Beta cells

Select the odd man out:

Question 1.
Skin, Brain, Kidneys, Lungs.
Answer:
Brain – It is a controlling organ whereas the others are excretory orgAnswer:

Question 2.
Gum, Resin, Urea, Latex
Answer:
Urea – It is an excretory product of animals whereas the others are excretory products of plants.

Question 3.
Gibberellin, Auxin, Thyroxine, Cytokinin.
Answer:
Thyroxine – It is a hormone in animals whereas the others are hormones in plants.

Question 4.
Dendrite, Cell body, Axon, Synapse.
Answer:
Synapse – It is a minute space between two adjacent neurons whereas the others are parts of the neuron.

Question 5.
Thyroxine, Calcitonin, Insulin, Auxin.
Answer:
Auxin – It is a plant hormone whereas the others are hormones in human beings.

Complete the Analogy:

(1) Water : Xylem :: Food : …………………………….
(2) Movement of root system : Gravitropic :: Movement of shoot system : …………………………….
(3) Brain: Cranial Cavity :: Spinal Cord : …………………………….
(4) Cavities of the brain : Ventricles :: Cavities of the spinal cord : …………………………….
(5) Involuntary activities : Medulla oblongata : : Balance of the body : …………………………….
(6) Stem elongation: Gibberellin :: Cell division : …………………………….
(7) Control of voluntary movements : Cerebrum :: Co-ordination of voluntary movements : …………………………….
(8) Converts glucose to glycogen : Insulin :: Converts glycogen to glucose : …………………………….
(9) Secondary sexual characters in males : Testosterone :: Secondary sexual characters in females : …………………………….
Answer:
(1) Phloem
(2) Phototropic
(3) Vertebral column
(4) Central canal
(5) Cerebellum
(6) Cytokinin
(7) Cerebellum
(8) Glucagon
(9) Oestrogen

Match the columns:

Question 1.

Column ‘A’	Column ‘B’
(1) Gibberellins (2) Cytokinins (3) Abscisic acid (4) Auxin	(a) Enlargement of cells (b) Helps in stem elogation (c) Cell division (d) Wilting of leaf

Answer:
(1 – b),
(2 – c),
(3 – d),
(4 – a).

Question 1.

Column ‘A’	Column B’
(1) Cerebrum (2) Cerebelleum (3) Medulla oblongata (4) Spinal cord	(a) Control of involuntary activities (b) Decision – making, memory and intellectual activities. (c) Centre for co­ordination of reflex actions (d) Maintaining body’s balance

Answer:
(1 – b),
(2 – d),
(3 – a),
(4 – c).

State whether the following statements are true or false. Correct the false statements.

Question 1.
Plants need less energy as compared to animals.
Answer:
True

Question 2.
Xylem conducts food whereas phloem conducts water.
Answer:
False. Xylem conducts water whereas phloem conducts food.

Question 3.
The loss of water from the plants is known as translocation.
Answer:
False. The loss of water from the plants is known as transpiration.

Question 4.
Calcium oxalate crystals present in some plants are called resins.
Answer:
False. Calcium oxalate crystals present in some plants are called raphides.

Question 5.
Root pressure helps to push the water up in plants during night time.
Answer:
True

Question 6.
Translocation is carried out by phloem in downward direction.
Answer:
False. Translocation is carried out by phloem in both upward and downward direction.

Question 7.
In unicellular organisms, waste materials are directly eliminated across the cell surface.
Answer:
True

Question 8.
Urea is produced in the liver.
Answer:
True

Question 9.
Systematic regulation of different processes is called co-ordination.
Answer:
False. Systematic regulation of different processes is called control.

Question 10.
A hormone auxin produced in the apical part of the shoot helps in enlargement of cells.
Answer:
True

Question 11.
Gibberellin helps in prevention and retardation of growth, leaf wilting etc.
Answer:
False. Abscisic acid helps in prevention and retardation of growth, leaf wilting etc.

Question 12.
The movement shown by venus fly trap while trapping an insect is a growth relevant movement.
Answer:
False. The movement shown by venus fly trap while trapping an insect is a growth irrelevant movement.

Question 13.
The lotus flower opens during night time while that of tuberose (polyanthus) opens during day time.
Answer:
False. The lotus flower opens during day time while that of tuberose (polyanthus) opens during night time.

Question 14.
Sensory neurons conduct impulses from the brain and the spinal cord to effector organs like muscles or glands.
Answer:
False. Sensory neurons conduct impulses from the sensory organs to the brain and the spinal cord.

Question 15.
There are 31 pairs of cranial nerves.
Answer:
False. There are 12 pairs of cranial nerves.

Question 16.
Activities like heart beat, blood circulation, breathing, sneezing, etc. are controlled by cerebellum.
Answer:
False. Activities like heart beat, blood circulation, breathing, sneezing, etc. are controlled by cerebellum.

Question 17.
Spinal nerves are associated with head, thorax and abdomen.
Answer:
False. Spinal nerves are associated with arms, legs, skin and some other parts of the body.

Question 18.
Nerve impulses are slow and long lasting whereas action of hormones is fast and short lived.
Answer:
False. Nerve impulses are fast and short lived whereas action of hormones is slow and long lasting.

Question 19.
Reflex actions are controlled by cerebellum.
Answer:
False. Reflex actions are controlled by spinal cord.

Question 20.
Thyroid stimulating hormone is secreted by the pituitary gland.
Answer:
True

Question 21.
The hormone thymosin is secreted by the thyroid gland.
Answer:
False. The hormone thymosin is secreted by the thymus gland.

Question 22.
Parathormone controls metabolism of calcium and phosphorns.
Answer:
True

Question 23.
The right kidney is slightly lower than the left kidney.
Answer:
True

Name the following:

Question 1.
The structural and functional unit of the nervous system.
Answer:
Newtron.

Question 2.
The network of capillaries in the Bowman’s capsule.
Answer:
Glomerulus.

Question 3.
The minute space between two adjacent nervous.
Answer:
Synapse.

Question 4.
The special cells which bring about control and co-ordination.
Answer:
Neurons.

Question 5.
The cavities present in various parts of the brain.
Answer:
Ventricles.

Question 6.
The long tubular cavity of the spinal cord.
Answer:
Central Canal.

Question 7.
The thread like fibrous structure at the end of the spinal cord.
Answer:
Filum terminale.

Give scientific reasons:

Question 1.
It is necessary to remove harmful and waste substances from the body.
Answer:

• Many harmful and waste substances like urea, uric acid, ammonia, etc. are produced in living organisms.
• If these substances accumulate in the body or are retained in the body for long, it can lead to serious harm or even death.
• Hence, it is necessary to remove such harmful and waste substances from the body.

Question 2.
In plants like Touch-me-not (Mimosa), movement also occurs at the places other than where it has been touched.
Answer:

• In plants like Touch-me-not (Mimosa), the information about the touch is relayed within the plant from one place to another.
• Plants use electro-chemical impulses for transfer of information from one place to another.
• Plant cells change their shape by increasing or decreasing their water content and thereby, bring about the movements of plants.
• Hence, in plants like Touch-me-not (Mimosa) movement also occurs at the places other than where it has been touched.

Question 3.
Endocrine glands are also called ductless glands.
Answer:

• Hormones are secreted by endocrine glands.
• These glands do not have any arrangement of their own to store or carry their secretions.
• Hence, as soon as hormones are produced, they are directly released into the blood circulation.
• Thus, though these endocrine glands are present at specific locations in our body, their secretions reach all parts of the body via blood.
• Therefore, endocrine glands are also called ductless glands.

Define the following:

Question 1.
Transportation
Answer:
The process by which a substance either synthesized or absorbed in one part of the body reaches another is called as transportation.

Question 2.
Control
Answer:
Systematic regulation of different processes is called as control.

Question 3.
Coordination
Answer:
Bringing about the different processes in the proper sequence is called as co-ordination.

Question 4.
Tropism or Tropic movement
Answer:
Movement or growth of any part of the plant in response to an external stimulus is called as tropism or tropic movement.

Question 5.
Excretion
Answer:
Removal of waste or harmful substances from the body is called excretion.

Question 6.
Dialysis
Answer:
The process of separating the nitrogenous waste from the blood with the help of a man?made machine is called dialysis.

Question 7.
Reflex action
Answer:
An immediate and involuntary response given to a stimulus from the environment is called a reflex action.

Question 8.
Homeostasis
Answer:
Proper co-ordination between various systems of an organism helps to maintain a state of equilibrium called homeostasis.

Question 9.
Tropism
Answer:
Movement or growth of any part of the plant in response to an external stimulus is called tropism.

Distinguish between:

Question 1.
Nervous control and Chemical control
Answer:

Nervous Control	Chemical Control
(i) Nervous control is brought about by special types of cells called neurons.	(i) Chemical control is brought about by chemical substances called hormones.
(ii) It involves the nervous system i.e., brain, spinal cord and nerves.	(ii) It involves the endocrine glands.
(iii) Nerve impulses are fast and short-lived.	(iii) Actions of hormones are very slow and long-lasting.

Question 2.
Growth relevant movements and growth irrelevant movements
Answer:

Growth relevant movements	Growth irrelevant movements
(i) Growth relevant movements result in growth of the plants.	(i) Growth irrelevant movements do not result in growth of the plants.
(ii) They are also called as tropic movements.	(ii) They are also called as nastic movements.
(iii) They are in response to stimulus of light, water, gravity, chemicals, etc.	(iii) They are generally in response to stimulus of touch.
(iv) Examples : Bending of stem towards light, movement of roots towards gravity and water, etc.	(iv) Example : Closing of leaflets of Mimosa plant, closing of Venus fly trap, etc.

Question 3.
Cerebrum and Cerebellum
Answer:

Cerebrum	Cerebellum
(i) It is the largest part of the brain.	(i) It is the smaller part of the brain.
(ii) It occupies two thirds of the brain.	(ii) It is situated below the cerebrum at the back of the cranial cavity.
(iii) Its surface has deep, irregular ridges and grooves which are called convolutions.	(iii) Its surface shows shallow grooves instead of convolutions.
(iv) It controls voluntary movements, concentration, planning, decision-making, memory, intelligence and intellectual activities.	(iv) It co-ordinates voluntary movements and maintains the body’s balance.

Write short notes:

Question 1.
Root Pressure
Answer:

• Root cells are in contact with water and minerals in the soil.
• Water and minerals enter the cells of the root surface due to difference in concentration. As a result, these cells become turgid.
• This is called root pressure.
• Under the effect of this pressure, water and minerals reach the xylem of the roots and to reduce this difference in concentration, they are continuously pushed forward.
• As a result of this continuous movement, a water column is formed, which is continuously pushed ahead.
• This pressure, is sufficient to lift the water up in shrubs, small plants and small trees.

Question 2.
Transpiration
Answer:

• Plants give out water in the form of water vapour through the stomata on their leaves. This is known as transpiration.
• Two cells called guard cells are present around the stomata. They control the opening and closing of stomata.
• Water is released into the atmosphere by leaves through the process of evaporation.
• As a result, water in the epidermal layer of the leaf decreases.
• Water is brought up to the leaves through the xylem to compensate for the lost water.
• Transpiration helps in absorption of water and minerals and distribution to all parts of the plant.

Question 3.
Nerve cell
Answer:

• Nerve cells also called as neurons are special types of cells which conduct impulses from one place to another in the body.
• Neurons are the structural and functional units of the nervous system.
• Nerve cells, the largest cell in the human body, may measure upto a few metres in length.
• Nerve cells have the ability to generate and conduct electrochemical impulse.
• The cells that support the nerve cells and help in their functioning are called neuroglia. Nerve cells and neuroglial cells together form nerves.

Question 4.
Reflex action
Answer:

• An immediate and involuntary response given to a stimulus from the environment is called a reflex action.
• Sometimes we react to an incident without any thinking on our part or control over the reaction.
• This is a response given to a certain stimulus from the surroundings.
• In such situations, proper control and co-ordination is achieved even without the intervention of the brain.
• For example, when our hand touches a hot object, the receptor in the skin detects the stimulus.
• The sensory neuron sends the impulse to the relay neuron in the spinal cord.
• The impulses are then sent to motor neurons which cause the muscles of the hand to contract and move away from the hot object.
• The spinal cord is the center of co-ordination for reflex actions.

Question 5.
Spinal cord
Answer:

• The spinal cord is the part of the central nervous system and it is held within the vertebral column.
• It is slightly thick but gradually tapers towards the end.
• There is a thread like fibrous structure at its end. It is called the filum terminale.
• The long tubular cavity of the spinal cord is called the central canal. It is filled with cerebrospinal fluid.
• The spinal cord conducts impulses from the skin towards the brain and from the brain to the muscles and glands.
• It functions as a centre of co-ordination of reflex actions.

Question 6.
Dialysis
Answer:

• The efficiency of kidneys can be adversely affected by injury, infection or decreased blood supply.
• If this happens, excess of toxic substances accumulates in the body and it can lead to death.
• If kidneys fail, nitrogenous wastes are separated from the blood with the help of a man-made machine.
• The process of separating the nitrogenous waste from the blood with the help of this machine is called dialysis.
• About 500 ml of blood is sent at one time through this machine. Purified blood is reinfused into the body of the patient.

Draw neat and labelled diagrams:

Question 1.
Vertical Section of Kidney
Answer:

Question 2.
Reflex action
Answer:

Name the hormones of the following endocrine glands and the function of each:

Question 1.
Parathyroid
Answer:

Hormone	Function
Parathormone	Controls metabolism of calcium and phosphorus

Question 2.
Pancreas
Answer:

Hormone	Function
(i) Glucagon	Stimulates liver to convert glycogen into glucose.
(ii) Insulin	Stimulates liver to convert excess blood glucose into glycogen.
(iii) Somatostatin	Controls levels of insulin and glucagon.
(iv) Pancreatic Polypeptide	Controls movement of intestine and thereby glucose absorption. Controls secretion of pancreatic juice.

Complete the following table of plant hormones with their functions:
Answer:

Plant hormone	Functions
(i) Auxin	Produced in the apical part of the shoot Helps in enlargement of cells
(ii) Gibberellins	Help in stem elongation
(iii) Cytokinins	Help in cell division
(iv) Abscisic acid	Effective in prevention and retardation of growth, leaf wilting, etc.

State the functions of different parts of the brain.
Answer:

Parts of the Brain	Functions
Cerebrum	Control of voluntary movements, concentration, planning, decision­making, memory, intelligence, and intellectual activities.
Cerebellum	(i) Co-ordination of voluntary movements. (ii)  Maintaining the body’s balance.
Medulla oblongata	Control of involuntary activities like the beating of the heart, blood circulation, breathing, sneezing, coughing, salivation, etc.
Spinal cord	(i) Conduction of impulses from the skin towards the brain. (ii) Conduction of impulses from brain to muscles and glands. (iii) Functions as centre of co­ordination of reflex actions.

Answer the following:

Question 1.
How do plants bring about movements in them?
Answer:

• Plants use electro-chemical impulses for transfer of information from one place to another.
• Plant cells change their shape by increasing or decreasing their water content and thereby bring about the movement of plants.

Answer the following:

Question 1.
What are growth-irrelevant movements? Give examples.
Answer:

• Some specific movements of the plants do not lead to the plant growth. Such movements are called growth-irrelevant movements.
• In the plant called venus fly trap, there is a trap that appears and smells like flowers and deceives insects. When an insect visits the flower-like trap, the trap closes up and the trapped insect is digested by the plant.
• Fibrils present on the leaves of the insectivorous plant Drosera, bend inward as soon as an insect lands on the leaves and surround the insects from all sides.
• In Balsam, the ripened fruit dehisces (bursts-open) at the right time to disperse the seeds.

Question 2.
Which are the different types of nerve cells or neurons?
OR
How are nerve cells classified according to their functions?
Answer:
According to their functions, nerve cells are classified into three types:

• Sensory neurons: They conduct impulses from the sensory organs to the brain and the spinal cord.
• Motor neurons : They conduct impulses from the brain or spinal cord to effector organs like muscles or glands.
• Association neurons : Association neurons perform the function of integration in the nervous system.

Question 3.
What are the different parts of the human nervous system?
Answer:
The human nervous system can be divided into the following three parts.

1. Central nervous system (CNS) : It consists of the brain and the spinal cord. It controls and regulates all activities of the body.
2. Peripheral nervous system (PNS) : The peripheral nervous system consists of the nerves originating from the central nervous system which connect the central nervous system with all parts of the body. They are of two types cranial nerves and spinal nerves.
3. Autonomic nervous system (ANS) : The autonomous nervous system consists of the nerves of involuntary organs like the heart, lungs, stomach etc. It is not under the control of our will.

Question 4.
Describe the structure of the central nervous system.
Answer:

• The central nervous system consists of the brain and spinal card.
• The organization of the brain is extremely delicate and highly evolved.
• The brain is the main controlling part of the nervous system and is safely located in the cranial cavity. The spinal cord is protected by the vertebral column.
• In the space between the delicate central nervous system and its bony covering are the protective layers called the meninges.
• Cavities present in various parts of the brain are called ventricles whereas the long tubular cavity of the spinal cord is called the central canal.
• The ventricles, central canal and spaces between the meninges are filled with cerebro?spinal fluid.
• This fluid supplies nutrients to the central nervous system and protects it from shock.

Question 5.
Which are the two types of peripheral nerves?
Answer:
Peripheral nerves are of two types:
(a) Cranial nerves:

• Nerves originating from the brain are called cranial nerves.
• They are associated with various parts in the head.
• There are 12 pairs of cranial nerves.

(b) Spinal nerves:

• Nerves originating from the spinal cord are called spinal nerves.
• They are associated with arms, legs, skin and some other parts of the body.
• There are 31 pairs of spinal nerves.

Question 6.
How do plants get rid of their excretory products?
Answer:

• Excretion is a simpler process in plants. There is no special organ or system for excretion in plants.
• Gases are given out by diffusion.
• Most of the waste substances of plants are stored in vacuoles of leaf-cells and in flowers, fruits and the bark of the stem. After some time these parts fall off.
• Some other waste materials are stored in old and worn out xylem in the form of resin and gum.
• Some waste materials are also given out through roots in the surrounding soil.

Answer in detail:

Question 1.
Explain how food and other substances are transported in plants?
OR
Explain translocation in plants.
Answer:

• The food produced in leaves is transported to each cell in the plant body.
• Excess food, except amino acids, is stored in roots, fruits and seeds. This process is called translocation of materials.
• It is carried out in both the upward and downward directions by the phloem.
• Translocation is not a simple process, it requires energy. This energy is obtained from ATP.
• Whenever food material like sucrose is transported towards a part of a plant via the phloem with the help of ATP, the water concentration decreases in the part. As a result, water enters the cell by the process of diffusion.
• The pressure on the cell wall increases due to increase in cellular contents.
• Due to the increase pressure, food is pushed into the neighbouring cells where the pressure is low.
• This process helps the phloem to transport the materials as per the need of the plant. During flowering season, the sugar stored in roots or stem is transported towards the floral buds to make them open and blossom.

Question 2.
What is tropic movement? Describe the different types of tropic movements.
OR
What are growth relevant movements? Describe the different types of growth relevant movements.
Answer:
Movement or growth of any part of the plant in response to an external stimulus is called tropic movement or tropism.

The different types of tropic movements are:

• Phototropic movement : The shoot system of any plant responds to the light stimulus, i.e., it grows towards the source of light. The movement shown by plants towards the source of light is called phototropic movement.
• Gravitropic movement : The root system of plants responds to stimulus of gravity. This is called gravitropic movement.
• Hydrotropic movement : The root system of plants responds to the stimulus of water. This is called hydrotropic movement.
• Chemotropic movement : Movement shown by plants in response to specific chemicals is called chemotropic movement. For example, the growth of the pollen tube towards the ovule.

All the above-mentioned movements of plants are related with growth, hence are called growth relevant movement.

Question 3.
Write short note on : Human Brain
Answer:

• The brain is the main controlling part of the nervous system and is safely located in the cranial cavity.
• The brain is covered by protective layers called the Meninges.
• Cavities present in various parts of the brain are called ventricles.
• The ventricles are filled with cerebrospinal fluid. This fluid supplies nutrients to the brain and also protects it from shock.
• The brain of an adult human weighs about 1300 -1400 grams and consists of approximately 100 million neurons.
• The left side of our brain controls the right side of our body and right side of our brain controls left side of the body.
• In addition, the left side of the brain controls our speech and conversation, writing, logical thinking etc., whereas the right side controls artistic abilities.

Human brain is made up of following parts:

(a) Cerebrum:

• This is the largest part of the brain and consists of two cerebral hemispheres. These hemispheres are joined with each other with the help of tough fibres and nerve tracts.
• The cerebrum occupies two-thirds of the brain. Hence, it is also called as large brain.
• Its surface has deep, irregular ridges and grooves which are called convolutions, convolution increases the surface area of the cerebrum and therefore a large number of nerve cells can be accommodated.

(b) Cerebellum:

• This is the smaller part of the brain situated below the cerebrum at the back of the cranial cavity.
• Its surface shows shallow grooves instead of deep convolutions.

(c) Medulla Oblongata:

• This is the hind-most part of the brain.
• There are two triangular swollen structures called pyramids on the upper side of medulla oblongata.
• The medulla oblongata continues downwards the spinal cord.

(6) How are nerve impulses conducted in the body?
Answer:

• Special types of cells which conduct impulses from one place to another in the body are called neurons. Nerve cells have the ability to generate and conduct electro-chemical impulses.
• The cells that support the nerve cells and help in their functioning are called neuroglia.
• All the information about our surroundings is collected by the ends or dendrites of the neuron.
• The chemical process begins at those ends and electric impulses are generated which are conducted from the dendrites to the cell body, from the cell body to the axon and from the axon to its terminal.
• These impulses are then to be transferred from this nerve cell to the next.
• Now the impulse that reaches the terminal of an axon, stimulates the nerve cell to secrete certain chemicals.
• These chemicals pass through a minute space, called the synapse, between two adjacent neurons and generate the impulses in the dendrites of the next neuron.
• In this way, impulses are conducted in the body and these impulses are finally conveyed by nerve cells to muscles cells or glands.

Read More:

FEDERALBNK Pivot Point Calculator

Balbharti Maharashtra State Board Class 10 Maths Solutions covers the Practice Set 1.4 Algebra 10th Class Maths Part 2 Answers Solutions Chapter 1 Similarity.

Practice Set 1.4 Algebra 10th Std Maths Part 2 Answers Chapter 1 Similarity

Question 1.
The ratio of corresponding sides of similar triangles is 3 : 5, then find the ratio of their areas.
Solution:
Let the corresponding sides of similar triangles be S₁ and S₂.
Let A₁ and A₂ be their corresponding areas.

∴ Ratio of areas of similar triangles = 9 : 25

Question 2.
If ∆ABC ~ ∆PQR and AB : PQ = 2:3, then fill in the blanks.
Solution:

Question 3.
If ∆ABC ~ ∆PQR, A(∆ABC) = 80, A(∆PQR) = 125, then fill in the blanks.
Solution:

Question 4.
∆LMN ~ ∆PQR, 9 × A(∆PQR) = 16 × A(∆LMN). If QR = 20, then find MN.
Solution:
9 × A(∆PQR) = 16 × A(∆LMN) [Given]
∴ \(\frac{\mathrm{A}(\Delta \mathrm{LMN})}{\mathrm{A}(\Delta \mathrm{PQR})}=\frac{9}{16}\) (i)
Now, ∆LMN ~ ∆PQR [Given]
∴ \(\frac{\mathrm{A}(\Delta \mathrm{LMN})}{\mathrm{A}(\Delta \mathrm{PQR})}=\frac{\mathrm{MN}^{2}}{\mathrm{QR}^{2}}\) (ii) [Theorem of areas of similar triangles]
∴ \(\frac{\mathrm{MN}^{2}}{\mathrm{QR}^{2}}=\frac{9}{16}\) [From (i) and (ii)]
∴ \(\frac{M N}{Q R}=\frac{3}{4}\) [Taking square root of both sides]
∴ \(\frac{\mathrm{MN}}{20}=\frac{3}{4}\)
∴ MN = \(\frac{20 \times 3}{4}\)
∴ MN = 15 units

Question 5.
Areas of two similar triangles are 225 sq. cm. and 81 sq. cm. If a side of the smaller triangle is 12 cm, then find corresponding side of the bigger triangle.
Solution:
Let the areas of two similar triangles be A₁ and A₂.
A₁ = 225 sq. cm. A₂ = 81 sq. cm.
Let the corresponding sides of triangles be S₁ and S₂ respectively.
S₁ = 12 cm

∴ The length of the corresponding side of the bigger triangle is 20 cm.

Question 6.
∆ABC and ∆DEF are equilateral triangles. If A(∆ABC): A(∆DEF) = 1:2 and AB = 4, find DE.
Solution:
In ∆ABC and ∆DEF,

Question 7.
In the adjoining figure, seg PQ || seg DE, A(∆PQF) = 20 sq. units, PF = 2 DP, then find A (꠸ DPQE) by completing the following activity.
Solution:
A(∆PQF) = 20 sq.units, PF = 2 DP, [Given]
Let us assume DP = x.
∴ PF = 2x

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 7 Energy Flow in an Ecosystem Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Science Solutions Chapter 7 Energy Flow in an Ecosystem

Class 9 Science Chapter 7 Energy Flow in an Ecosystem Textbook Questions and Answers

1. Complete the following table (Carefully study the carbon, oxygen and nitrogen cycles).

Bio-geo-chemical cycles	Biotic processes	Abiotic processes
1. Carbon cycle
2. Oxygen cycle
3. Nitrogen cycle

2. Correct and rewrite the following statements and justify your corrections.
a. Carnivores occupy the second trophic level in the food chain.
b. The flow of nutrients in an ecosystem is considered to be a ‘one-way’ transport.
c. Plants in an ecosystem are called primary consumers.

3. Give reasons.
a. Energy flow through an ecosystem is ‘one way’.
Answer:

• The Sun is the most important source of energy in any ecosystem.
• Green plants of the ecosystem store some amount of solar energy in the form of food.
• Before reaching the decomposers, this energy is passed on from one trophic level to the next.
• Decomposers dissipate some amount of energy in the form of heat.
• However, no part of the energy ever returns to the Sun. Hence, energy flow through an ecosystem is ‘one way’.

b. Equilibrium is necessary in the various bio-geo-chemical cycles.
Answer:

• The cyclic flow of nutrients within an ecosystem is called bio-geo-chemical cycles.
• Nutrients, necessary for the growth of organisms are continuously transferred from abiotic to biotic factors and biotic to abiotic factors within an ecosystem.
• Any imbalance in the cycles will break the link between the biotic and abiotic factors.
• Therefore, equilibrium is necessary between bio-geo-chemical cycles.

c. Flow of nutrients through an ecosystem is cyclic.
Answer:

• All organisms need nutrients for their growth.
• The nutrients carbon, oxygen, nitrogen, iron, calcium etc. are circulated and recycled from the biosphere to living organisms and after their death back to the biosphere.
• Nutrients are taken up by plants and then passed on to the consumers.
• Eventually, after their death, all types of consumers, are decomposed by decomposers like bacteria and fungi and the nutrients are again released into the biosphere and are, used again by living organisms.

Therefore, the flow of nutrients through an ecosystem is cyclic.

4. Explain the following cycles in your own words with suitable diagrams.
a. Carbon cycle.

Answer:

• The circulation and recycling of carbon from the atmosphere to living organisms and after their death back to the atmosphere is called the carbon cycle.
• Abiotic carbon atoms are circulated and recycled into biotic form mainly through photosynthesis and respiration.
• Hence, the carbon cycle is one of the important bio-geochemical cycles.
• Plants convert carbon dioxide into carbohydrates by the process of photosynthesis.
• Similarly, they produce carbon compounds like proteins and fats, too.
• Carnivores feed upon herbivores. In this way, biotic carbon is transported from plants to herbivores, from herbivores to carnivores and from carnivores to apex consumers.
• Main processes in the carbon cycle
  
• Eventually, after death, all types of consumers, are decomposed by decomposers like bacteria and fungi and carbon dioxide is released again into the atmosphere and is used again by living organisms.
• In this way, carbon is continuously passed on from one living organism to another. After the death of living organisms, carbon goes to the atmosphere and is again taken up by living organisms.

b. Nitrogen cycle.
Answer:

• Nitrogen forms 78% i.e. the maximum portion of the atmosphere. It is necessary for the maintenance of the cycle of nature.
• The circulation and recycling of nitrogen gas into the form of different compounds through various biotic and abiotic processes in nature is called the nitrogen cycle.
• All organisms participate in the nitrogen cycle. It is an important component of proteins and nucleic acids.
• As compared to other elements, it is inactive and does not easily combine with other elements. Most organisms cannot use the free form of nitrogen.
• Important processes of nitrogen cycle:
  (a) Nitrogen fixation: Conversion of nitrogen into nitrates and nitrites through atmosphere, industrial and biological processes.
  (b) Ammonification: Release of ammonia through the decomposition of dead bodies and excretory wastes of organisms.
  (c) Nitrification: Conversion of ammonia into a nitrite and then nitrate.
  (d) Denitrification: Conversion of nitrogen compounds into gaseous nitrogen.

c. Oxygen cycle.
Answer:

1. Oxygen forms 21% of the atmosphere. It is also present in the hydrosphere and lithosphere. The circulation and recycling of oxygen within the biosphere is called the oxygen cycle.
2. This cycle, includes both the biotic and abiotic components. Oxygen is continuously produced as well as used up in the atmosphere.
3. Oxygen is highly reactive and it readily reacts with other elements and compounds.
4. As oxygen is found in various forms like molecular oxygen (Oz), water (H,0), carbon dioxide (C02), inorganic compounds etc, the oxygen cycle of the biosphere is extremely complex.
5. Oxygen is released in the process of photosynthesis, whereas it is used up in processes like respiration, combustion, decomposition, corrosion, rusting, etc.

5. What would you do to help maintain the equilibrium in the various bio-geochemical cycles? Explain in brief.
Answer:

• Bio-geo-chemical cycles always involve the achievement of equilibrium, i.e., a balance in the cycling of the nutrients between the spheres.
• Human activities that are known to be environmentally unfriendly can disrupt this balance.
• We should avoid deforestation as trees play an important role in maintaining the balance.
• We should avoid overuse of fertilizers. The fertilizers get washed away in the nearby water bodies disrupting the balance.
• Avoid burning of fossil fuels as these fuels release a large amount of carbon in the form of carbondioxide, thus disrupting the balance.
• Vehicular emissions is another contributor to the disruption in balance of the various cycles.
• These emissions release oxides of nitrogen and carbon and other hazardous air pollutants.
• So, we must use better quality fuel like CNG or ethanol to reduce vehicular emissions.

6. Explain in detail the inter-relationship between the food chain and food web.
Answer:

• Interaction go on continuously between producers, consumers and decomposers.
• There is a definite sequence in these interactions which is called the food chain.
• Each chain consists of four, five or more links.
• An ecosystem consists of many food chains that are interconnected at various levels. Thus, a food web is formed.
• An organism may be the prey for many other organisms.
• For example, an insect feeds upon leaves of various plants but the same insect is the prey for different animals like frog, wall lizard, birds, etc.
• Thus, many food chains interconnected together form an intricate web called as food web.

7. State the different types of bio-geochemical cycles and explain the importance of those cycles.
Answer:

• The different types of bio-geo-chemical cycles are nitrogen, oxygen, carbon, water vapour, iron, calcium, phosphorus, etc.
• Nutrients, necessary for the growth of the organisms are continuously transferred from abiotic to biotic factors and biotic to abiotic factors within an ecosystem.
• These cycles operate continuously through the medium of the biosphere formed by the lithosphere, atmosphere and hydrosphere.
• (iv) The recycling of biological, geological and chemical sources of nutrients takes place through these cycles.
• Nutrients from the biosphere enter the bodies of plants and animals. Eventually, after death, all types of consumers are decomposed by decomposers like bacteria and fungi and they are again released into the biosphere and are used again by living organisms.
• Therefore, these cycles help in maintaining the flow of nutrients and energy through ecosystem and maintaining the equilibrium in the ecosystem.

8. Explain the following with suitable examples.
a. What type of changes occur in the amount of energy during its transfer from plants to apex consumers?
Answer:

• Plants of the ecosystem store some of the solar energy in the form of food.
• Before reaching the decomposers, this energy is passed on from one trophic level to the next.
• At every trophic level, some amount of energy is used by the organism for its own life processes and some amount of energy is lost to the surroundings.
• Decomposers dissipate some amount of energy in the form of heat.
• However, no part of the energy ever returns to the Sun. Hence, such passage of energy is referred to as ‘one way’ transport.
• Therefore, energy is maximum at the base of the pyramid and is least at the apex, e.g.
• phytoplanktons which form the base of the pyramid have 10,000 kcal of energy while humans at the apex have 10 kcal of energy.

b. What are the differences between flow of matter and of energy in an ecosystem? Why?
Answer:

Flow of matter	Flow of energy
(i) It involves the circulation and recycling of nutrients in a cyclic manner within the biosphere.	(i) It involves the flow of energy from one trophic level to another in a unidirectional or non-cyclic manner.
(ii) There is no dissipation of matter at any level.	(ii) There is the dissipation of energy at every level.
(iii) Biosphere is the source of nutrients.	(iii) The Sun is the most important source of energy.

Class 9 Science Chapter 7 Energy Flow in an Ecosystem Intext Questions and Answers

Can you recall?

7 Energy Flow In An Ecosystem Exercises  Question 1.
What is meant by nitrogen fixation?
Answer:
The process of conversion of Nitrogen into nitrates and nitrites is called Nitrogen fixation.

Energy Flow In An Ecosystem Class 9 Questions And Answers Question 2.
Which microbes bring about the process of nitrogen fixation?
Answer:
Rhizobium present in the root nodules of the leguminous plant bring about the process of nitrogen fixation.

Class 9 Science Chapter 7 Energy Flow In An Ecosystem Question 3.
What is meant by ‘ecosystem’?
Answer:
An ecosystem includes all of the living things like plants, animals and other organisms in a given area, interacting with each other and also with non-living environmental factors like weather, earth, sun, soil, climate and atmosphere.

Energy Flow In An Ecosystem Class 9 Exercise 1Question 4.
Which are different types of ecosystems?
Answer:

Class 9 Science Chapter 7 Energy Flow In An Ecosystem Exercise Question 5.
How do interactions take place between biotic and abiotic factors of an ecosystem?
Answer:

• Abiotic factors include non-living factors such as soil, water etc. and biotic factors include all living organisms.
• Both these abiotic and biotic ecosystems are connected through various bio-geo-chemical cycles.
• These connections/interactions are important for the flow of matter and flow of energy.

Class 9 Science Chapter 7 Energy Flow in an Ecosystem Additional Important Questions and Answers

Choose and write the correct option:

Question 1.
An intricate network of food chains is called
(a) Biosphere
(b) Food web
(c) Energy pyramid
(d) Ecosystem
Answer:
(b) food web

Question 2.
Fungi and other microbes are called
(a) Producers
(b) Consumers
(c) Decomposers
(d) Omnivores
Answer:
(c) decomposers

Question 3.
Oxygen forms of the atmosphere.
(a) 78%
(b) 21%
(c) 10%
(d) 90%
Answer:
(b) 21%

Question 4.
Microbes which do not need oxygen are called
(a) Producers
(b) Aerobes
(c) Anaerobes
(d) Decomposers
Answer:
(c) anaerobes

Question 5.
The pattern of energy exchange in an ecosystem is called a
(a) Food chain
(b) Food web
(c) Pyramid of energy
(d) Trophic levels
Answer:
(c) Pyramid of energy

Question 6.
Carbon atoms are circulated and recycled through
(a) Nitrification and denitrification
(b) Photosynthesis and respiration
(c) Respiration and nitrification
(d) Photosynthesis and ammonification
Answer:
(b) photosynthesis and respiration

Question 7.
Conversion of ammonia into a nitrite and then nitrate is called
(a) Nitrogen fixation
(b) Denitrification
(c) Nitrification
(d) Ammonification
Answer:
(c) nitrification

Question 8.
The conversion of nitrogen compounds into gaseous nitrogen is called
(a) Nitrogen fixation
(b) Denitrification
(c) Ammonification
(d) Nitrification
Answer:
(b) denitrification

Question 9.
is an important component of proteins and nucleic acids.
(a) Carbon
(b) Nitrogen
(c) Phosphorus
(d) Oxygen
Answer:
(b) Nitrogen

Question 10.
Amount of matter and energy from the lowest level to the highest level.
(a) decreases
(b) increases
(c) remains the same
(d) multiplies
Answer:
(a) decreases

Question 11.
is the most important source of energy in any ecosystem.
(a) The Sun
(b) The Moon
(c) Producers
(d) Decomposers
Answer:
(a) The Sun

Question 12.
Flow of energy in an ecosystem is
(a) cyclical
(b) two way transport
(c) o ne way transport
(d) to and fro transport
Answer:
(c) one way transport

Question 13.
The Indian Institute of Ecology and Environment, Delhi, has published
(a) Invasive species in a changing Environment
(b) Encyclopaedia of Ecology and Environment
(c) Environment and Ecology Magazine
(d) Biodiversity and Disaster Management
Answer:
(b) Encyclopaedia of Ecology and Environment

Question 14.
Oxygen is released in the process of
(a) Respiration
(b) Decomposition
(c) Combustion
(d) Photosynthesis
Answer:
(d) photosynthesis

Question 15.
cycle is a gaseous cycle.
(a) Carbon
(b) Phosphorus
(c) Calcium
(d) Iron
Answer:
(a) Carbon

Question 16.
is a sedimentary cycle.
(a) Carbon
(b) Nitrogen
(c) Oxygen
(d) Calcium
Answer:
(d) Calcium

Question 17.
is a primary consumer.
(a) Elephant
(b) Frog
(c) Owl
(d) Tiger
Answer:
(a) Elephant

Question 18.
is a secondary consumer.
(a) Grasshopper
(b) Elephant
(c) Frog
(d) Human
Answer:
(c) Frog

Question 19.
Tiger is a /an
(a) Producer
(b) Primary consumer
(c) Apex consumer
(d) Secondary consumer
Answer:
(c) apex consumer

Question 20.
Carbon dioxide is released into the atmosphere through
(a) burning of fossil fuels
(b) volcanic activity
(c) respiration
(d) all of these
Answer:
(d) all of these

Question 21.
in 1942 studied the food chain and energy flow through it
(a) Linderman
(b) Darwin
(c) Calypso
(d) Chu win lee
Answer:
(a) Linderman

Question 22.
fter the death of apex consumers, energy becomes available to.
(a) Decomposers
(b) Producers
(c) Herbivores
(d) Carnivores
Answer:
(a) Decomposers

Question 23.
Green plants of the ecosystem store in the form of food.
(a) Solar energy
(b) Chemical energy
(c) Thermal energy
(d) Electrical energy
Answer:
(a) Solar energy

Question 24.
Plants convert carbon dioxide into by the process of photosynthesis.
(a) Carbohydrates
(b) Proteins
(c) Fats
(d) Vitamins
Answer:
(a) Carbohydrates

Question 25.
Carnivores feed upon
(a) Decomposers
(b) Herbivores
(c) Producers
(d) Secondary producers
Answer:
(b) Herbivores

Question 26.
is used up in the processes like respiration, combustion, decomposition, corrosion, rusting, etc.
(a) Nitrogen
(b) Oxygen
(c) Argon
(d) Helium
Answer:
(b) Oxygen

Question 27.
Nitrogen forms % of the atmosphere.
(a) 79
(b) 78
(c) 21
(d) 2
Answer:
(b) 78

Question 28.
Most organisms cannot use the free form of
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Carbon monoxide
Answer:
(b) Nitrogen

Question 29.
first proposed the concept of Ecological Pyramid in 1927.
(a) Darwin
(b) Newton
(c) Elton
(d) Edison
Answer:
(c) Elton

Question 30.
Ecological Pyramid is called
(a) Hills
(b) Mounts
(c) Eltonian
(d) Darwinism
Answer:
(c) Eltonian

Question 31.
is produced from oxygen through various atmospheric processes.
(a) Nitrogen dioxide
(b) Nitrites
(c) Ozone
(d) CFC
Answer:
(c) Ozone

Question 32.
Interactions between producers, consumers and saprophytes in a definite sequence is called
(a) Links
(b) Internet
(c) Food chain
(d) Connectors
Answer:
(c) Food chain

Question 33.
Many food chains interconnected at various levels is called
(a) Links
(b) Internet
(c) Connectors
(d) Food web
Answer:
(d) Food web

Question 34.
Decomposers dissipate some amount of energy in the form of
(a) Light
(b) Electricity
(c) Sound
(d) Heat
Answer:
(d) Heat

Question 35.
The flow of nutrients in an ecosystem is
(a) Non- cyclic
(b) Mono directional
(c) Reverse directional
(d) Cyclical
Answer:
(d) Cyclical

Question 36.
The cyclical flow of nutrients within an ecosystem is called
(a) Biological cycle
(b) Chemical cycle
(c) Solar cycle
(d) Bio-geo chemical cycle
Answer:
(d) Bio-geo chemical cycle

Question 37.
is an accumulation of the main abiotic gaseous nutrient materials found in the earth’s atmosphere.
(a) Gaseous cycle
(b) Water cycle
(c) Solar cycle
(d) Lunar cycle
Answer:
(a) Gaseous cycle

Question 38.
Oxygen is released into the atmosphere by the process of
(a) Photosynthesis
(b) Respiration
(c) Oxidation
(d) Decomposition
Answer:
(a) Photosynthesis

Question 39.
Charles Elton studied the of the Beer islands in England..
(a) Tundra ecosystem
(b) Mediterranean ecosystem
(c) Equatorial ecosystem
(d) Taiga ecosystem
Answer:
(a) Tundra ecosystem

Question 40.
in 1942 studied the food chain and energy flow through it.
(a) Charles Elton
(b) Lindeman
(c) Robert Whittaker
(d) Eichler
Answer:
(b) Lindeman

Question 41.
After the death of apex consumers, energy becomes available to
(a) Primary consumer
(b) Secondary consumer
(c) Decomposer
(d) Sun
Answer:
(c) Decomposer

Question 42.
Nitrogen forms % of the atmosphere.
(a) 28%
(b) 78%
(c) 48%
(d) 82%
Answer:
(b) 78%

Question 43.
first proposed the concept of the Ecological Pyramid in 1927.
(a) Charles Elton
(b) Lindeman
(c) Eichler
(d) John Muir
Answer:
(a) Charles Elton

Question 44.
Oxygen is released into the atmosphere by the process of
(a) respiration
(b) Photosynthesis
(c) Combustion
(d) All of these
Answer:
(b) Photosynthesis

Find the odd man out:

Question 1.
Photosynthesis, Respiration, Decomposition, Forest Fires
Answer:
Forest Fires

Question 2.
Combustion, Corrosion, rusting, formation of ozone, Photosynthesis
Answer:
Photosynthesis

Question 3.
Biological nitrogen fixation, ammonification, nitrification, denitrification, industrial nitrogen fixation
Answer:
Industrial nitrogen fixation

Question 4.
Frog, Owl, Squirrel, Fox
Answer:
Squirrel

Question 5.
Grasshopper, squirrel, elephant, lion
Answer:
Lion

Question 6.
Nitrogen cycle, oxygen cycle, carbon cycle, phosphorus cycle
Answer:
Phosphorus cycle

Question 7.
Photosynthesis, Nitrification, Ammonification, Denitrification
Answer:
Photosynthesis

Find out the correlation:

1. Grasshopper : Primary consumer :: Tiger : ………………..
2. Owl : Secondary consumer :: Squirrel : ………………..
3. Flow of energy : One way :: Flow of nutrients : ………………..
4. Plants : Producers :: Bacteria and Fungi : ………………..
5. Nitrogen : Gaseous cycle :: Phosphorus : ………………..
6. Oxygen : 21% :: Nitrogen : ………………..
7. Photosynthesis: Carbon cycle:: Ammonification : ………………..
8. Respiration : Oxygen cycle :: Nitrification : ………………..
9. Respiration : Biotic process :: Combustion : ………………..
10. Microbes using oxygen : Aerobes :: Microbes not using oxygen : ………………..
Answer:
(1) Apex consumer
(2) Primary consumer
(3) Cyclic
(4) Decomposers
(5) Sedimentary cycle
(6) 78%
(7) Nitrogen cycle
(8) Nitrogen cycle
(9) Abioticprocess
(10) Anaerobes

Q.l. (B) 3. Difference between:
(1) Azotobacter and Rhizobium
Answer:

Azotobacter	Rhizobium
Free-living nitrogen-fixing bacteria	Symbiotic nitrogen-fixing bacteria

(2) Biotic components and Abiotic component
Answer:

Biotic components	Abiotic component
Living component of an ecosystem	Physical/Chemical non-living components of an ecosystem

(3) Producers and Herbivores
Answer:

Producers	Herbivores
They are present in the 1st trophic level	They are present in the 2nd trophic level

(4) Carnivores and Herbivores
Answer:

Carnivores	Herbivores
They depend on Herbivores for nutrition	They depend on Producers for nutrition

(5) Phosphorus and Carbon
Answer:

Phosphorus	Carbon
It cycles through the Sedimentary cycle	It cycles through the Gaseous cycle

(6) Food chain and Food web
Answer:

Food chain	Food web
Interactions between producers, consumers and decomposers in a definite sequence is called as a food chain.	The interconnection among different food chains in an ecosystem at various levels is called as a food web

State whether the following statements are true or false. Correct the false statements:

(1) Herbivores occupy the third trophic level in a food chain.
(2) Apex consumers use herbivores and carnivores as their food.
(3) Humans are apex consumers.
(4) Omnivores feed only on carnivores.
(5) A food chain has two links.
(6) The number of consumers in a food web is fixed.
(7) The amount of matter and energy goes on increasing at every level in a food chain.
(8) Robert Brown first proposed the concept of Ecological Pyramid.
(9) After the death of apex consumers, the energy becomes available to decomposers.
(10) The gaseous cycle is a speedier cycle than the sedimentary cycle.
(11) Climatic changes and human activities seriously affect the speed, intensity and equilibrium of bio-geo-chemical cycles.
(12) Carbon dioxide is released in the atmosphere through photosynthesis.
(13) The equilibrium of oxygen and carbon dioxide gases is maintained by decomposers.
(14) The conversion of ammonia into a nitrite and then nitrate is called nitrogen fixation.
(15) Conversion of nitrogen compounds into gaseous nitrogen is called nitrogen fixation.
(16) Release of ammonia through decomposition of dead plants and excretory wastes of organisms is called ammonification.
(17) The cyclic flow of nutrients within an ecosystem is called Energy Pyramid.
Answer:
(1) False, herbivores occupy the second trophic level in a food chain as they are directly dependent on producers.
(2) True
(3) True
(4) False. Omnivores feed on both herbivores and carnivores.
(5) False. A food chain consists of four, five or more links.
(6) False. A food web can have many consumers.
(7) False. The amount of matter and energy goes on decreasing at every level in a food chain.
(8) False. Charles Elton first proposed the concept of Ecological Pyramid.
(9) True
(10) True
(11) True
(12) False. Carbon dioxide is released in the atmosphere through respiration, burning of fossil fuels and wood, forest fires and volcanic activity. (13) False. The equilibrium of oxygen and carbon dioxide gases is maintained by plants.
(14) False. The conversion of ammonia into a nitrite and then nitrate is called nitrification.
(15) False. Conversion of nitrogen compounds into gaseous nitrogen is called denitrification.
(16) True
(17) False. The cyclic flow of nutrients within an ecosystem is called bio-geochemical cycle.

Name the following:

Question 1.
The animals that feed on herbivores.
Answer:
Carnivores.

Question 2.
Organisms that feed on herbivores and carnivores.
Answer:
Omnivores.

Question 3.
Two examples of primary consumers.
Answer:
Grasshopper, squirrel.

Question 4.
Two examples of secondary consumers.
Answer:
Frog, owl.

Question 5.
Two examples of Apex consumers.
Answer:
Lion, tiger.

Question 6.
Levels in the food chain.
Answer:
Trophic level.

Question 7.
Organisms that decompose the dead bodies of plants and animals.
Answer:
Decomposers.

Question 8.
Process which releases oxygen.
Answer:
Photosynthesis.

Question 9.
Release of ammonia through decomposition of dead bodies and excretory wastes of organisms.
Answer:
Ammonification.

Question 10.
Conversion of nitrogen into nitrates and nitrites through atmospheric, industrial and biological processes.
Answer:
Nitrogen fixation.

One line answers:

Question 1.
What is Food chain?
Answer:
Interactions between producers, consumers and decomposers in a definite sequence is called as a food chain.

Question 2.
What is Food web?
Answer:
The interconnection among different food chains in an ecosystem at various levels is called as a food web.

Question 3.
What is Trophic level?
Answer:
A trophic level is the step at which the organism obtains its food in the chain.

Question 4.
What is Pyramid of energy?
Answer:
The pattern of energy exchange in an ecosystem is called a ‘Pyramid of energy’.

Question 5.
What is Bio-geo-chemical cycle?
Answer:
The cyclical flow of nutrients within an ecosystem is called bio-geo-chemical cycle.

Question 6.
What is Carbon cycle?
Answer:
The circulation and recycling of carbon from the atmosphere to living organisms and aher their death back to the atmosphere is called the carbon cycle.

Question 7.
What is Oxygen cycle?
Answer:
The circulation and recycling of oxygen within the biosphere is called as oxygen cycle.

Question 8.
What is Nitrogen cycle?
Answer:
The circulation and recycling of nitrogen gas into the form of different compounds through various biotic and abiotic processes in nature is called the nitrogen cycle.

Question 9.
What is Nitrogen fixation?
Answer:
The process of conversion of free nitrogen gas of the atmosphere into nitrogen compounds is called of nitrogen fixation.

Distinguish between:

Question 1.
Gaseous Cycle and Sedimentary Cycle.
Answer:

Gaseous Cycle	Sedimentary Cycle
(i)      It is an accumulation of the main abiotic gaseous nutrient materials found in the earth’s atmosphere. (ii)    It includes nitrogen, oxygen, carbon dioxide, water vapour etc.	(i)     It is an accumulation of the main abiotic nutrient materials found in the soil, sediment and sedimentary rocks, etc. of the earth. (ii)    It includes soil components like iron, calcium, phosphorus etc.

Question 2.
Carbon Cycle and Nitrogen Cyde.
Answer:

Carbon Cycle	Nitrogen Cycle
(i) The circulation and recycling of carbon from the atmosphere to living organisms and after their death back to the atmosphere is called the carbon cycle.	(i) The circulation and recycling of nitrogen into the form of different compounds through various biotic and abiotic processes in nature is called the nitrogen cycle.
(ii) Main processes involved in the carbon cycle are photosynthesis and respiration.	(ii) Main processes involved in the nitrogen cycle are nitrogen fixation, ammonification, nitrification and denitrification.
(iii) Carbon in the form of carbon dioxide is directly absorbed by plants for photosynthesis.	(iii) Nitrogen gas cannot be directly absorbed by plants. So nitrogen is fixed by the process of nitrogen fixation and then absorbed from the soil.

Complete the flow chart:

Question 1.
Energy Pyramid.

Question 3.
Nitrogen Cycle

Question 4.
Bio-Geo Chemical cycle

Write short notes on:

Question 1.
Trophic level.
Answer:

• Each level in the food chain is called a trophic level.
• A trophic level is the step at which the organism obtains its food in the chain.
• The amount of matter and energy gradually decreases from producers at the lowest level to the top consumers at the highest level.

Question 2.
Food web.
Answer:

• An ecosystem consists of many food chains that are interconnected at various levels. This is called food web.
• An organism may be the prey for many other organisms.
• For example, an insect feeds upon leaves of various plants but the same insect is the prey for different animals like wall lizards, birds etc.
• This forms an intricate web instead of a linear food chain. Such an intricate network is called as food web.
• Generally food webs are formed everywhere in nature.

Question 3.
Energy Pyramid.

Answer:

• Each level in the food chain is called a trophic level.
• The amount of matter and energy gradually decreases from producers at the lowest level to the top consumers at the highest level.
• The initial quantity of energy goes on decreasing at every level of energy exchange.
• Similarly, the number of organisms also decreases from the lowest level to the highest level.
• This pattern of energy exchange in an ecosystem is called a Pyramid of energy.

Explain the following statements

Question 1.
justify the statements
(a) Producers form the first trophic level in the food chain. Herbivores depend directly on producers.
(b) The flow of nutrients in an ecosystem is cyclic.
(c) Plants in an ecosystem are called autotrophs.
Answer:

1. So herbivores form the second trophic level, whereas carnivores depend on herbivores, so they form the third trophic level in the food chain.
2. The nutrients are circulated and recycled from the biosphere to living organisms and after their death back to the biosphere.
3. They produce their own food by the process of photosynthesis. All animals in an ecosystem directly or indirectly depend on plants for food.

Explain the diagram

Question 1.
Food chain in a forest ecosystem:

Answer:

• In a forest ecosystem, grass is eaten by a deer, which in turn is eaten by a tiger.
• The grass, deer and tiger form a food chain.
• In this food chain, energy flows from the grass (producer) to the deer (primary consumer) to the tiger (secondary consumer).

Question 2.
Food chain in an aquatic ecosystem (Pond)

Answer:

• In a aquatic ecosystem algae are eaten by insects.
• Insects are eaten by small fish, small fish are in turn eaten by big fish.
• And the big fish are eaten by fish eating birds.
• In this food chain, energy flows from the algae (producer) to the insects (primary consumers) to the small fish (secondary consumers) to the big fish (tertiary consumer) and to the fish eating birds (apex consumer).

Question 3.
Carbon cycle

Answer:

• The circulation and recycling of carbon from the atmosphere to living organisms and after their death back to the atmosphere is called carbon cycle.
• Main processes involved in carbon cycle are photosynthesis and respiration.
• Carbon in the form of carbon dioxide is directly absorbed by plants for photosynthesis

Question 4.
Nitrogen cycle

Answer:
(i) The circulation and recycling of nitrogen into the form of different compounds through various biotic and abiotic processes in nature is called the nitrogen cycle.
(ii) Main processes involved in nitrogen cycle are nitrogen fixation, ammonification, nitrification and denitrification.
(iii) Nitrogen gas cannot be directly absorbed by plants. So nitrogen is fixed by the process of nitrogen fixation and then absorbed from the soil.

Question 5.
Oxygen cycle

Answer:

1. Oxygen forms 21% of the atmosphere. It is also present in the hydrosphere and lithosphere.
2. Circulation and recycling of oxygen within the biosphere is called the oxygen cycle.
3. This cycle, includes both the biotic and abiotic components.
4. Oxygen is continuously produced as well as used up in the atmosphere.
5. Oxygen is highly reactive and it readily reacts with other elements and compounds.
6. As oxygen is found in various forms like molecular oxygen (O₂), water (H₂O), carbon dioxide (CO₂), inorganic compounds etc, the oxygen cycle of the biosphere is extremely complex.
7. Oxygen is released in the process of photosynthesis, whereas it is used up in processes like respiration, combustion, decomposition, corrosion, rusting, etc.

Answers based on figures.

Question 1.
Nitrogen Cycle

Answer:

• Oxygen forms 21% of the atmosphere. It is also present in the hydrosphere and lithosphere.
• The circulation and recycling of oxygen within the biosphere is called the oxygen cycle.
• This cycle, includes both the biotic and abiotic components.
• Oxygen is continuously produced as well as used up in the atmosphere.
• Oxygen is highly reactive and it readily reacts with other elements and compounds.
• As oxygen is found in various forms like molecular oxygen (O₂), water (H₂O), carbon dioxide (CO₂), inorganic compounds etc, the oxygen cycle of the biosphere is extremely complex.
• Oxygen is released in the process of photosynthesis, whereas it is used up in processes like respiration, combustion, decomposition, corrosion, rusting, etc.

Answers based on figures.

Question 1.
Nitrogen Cycle

(i) Is nitrogen a reactive gas?
Answer:
Nitrogen in its atmospheric state non-reactive gas

(ii) Name process of nitrogen conversion from atmosphere to green plants.
Answer:
Nitrogen fixation is the process of nitrogen conversion atmosphere to green plants

(iii) Name the process of converting usable nitrogenous products into atmospheric inert nitrogen.
Answer:
Denitrification is the process of converting usable nitrogenous products into atmospheric inert nitrogen

(iv) Animals produce which product of nitrogen?
Answer:
Animals produce ammonia as a product of nitrogen

(v) Name two nitrifying organisms.
Answer:
Azotobacter and Rhizobium are the two nitrifying organisms

(vi) Which type of bio-geo-chemical cycles does nitrogen follow?
Answer:
Nitrogen follows gaseous and sedimentary bio-geo-chemical cycles

Question 2.
Carbon cycle

(i) Is carbon dioxide gas freely available in the atmosphere?
Answer:
Carbon dioxide gas is freely available in the atmosphere

(ii) How is carbon found in water?
Answer:
Carbon is found in water in the form of carbonates

(iii) How are we using carbon as a fuel?
Answer:
Fossil fuels are a form of carbon which are used as fuel by us

(iv) How to plants use carbon as their food source?
Answer:
Plants take up carbon in photosynthesis and convert it into starch which is their food source

(v) How do animals use carbon?
Answer:
Animals use carbon in form of organic compounds and inorganic compounds

(vi) Which type of bio-geo-chemical cycles does carbon follow?
Answer:
Carbon follows gaseous and sedimentary bio-geo-chemical cycles

Question 3.
Oxygen cycle

(i) Is oxygen gas freely available in the atmosphere?
Answer:
Oxygen gas is freely available in the atmosphere

(ii) How is oxygen used by animals?
Answer:
Oxygen is used in respiration by the animals

(iii) How are we using carbon as a fuel?
Answer:
Fossil fuels are a form of carbon which are used as fuel by us

(iv) How to plants use carbon as their food source?
Answer:
Plants take up carbon in photosynthesis and convert it into starch which is their food source

(v) How do animals use carbon?
Answer:
Animals use carbon in form of organic compounds and inorganic compounds

(vi) Which type of bio-geo-chemical cycles does carbon follow?
Answer:
Carbon follows gaseous and sedimentary biogeo-chemical cycles

Question 4.
Food web

(i) What is the basic unit of food web?
Answer:
The basic unit of food web is food chain

(ii) Which organisms are on the 1st level of this food web?
Answer:
Producers are p. the 1st level of this food web

(iii) What are the animals which depend on producers directly for nutrition called?
Answer:
The animals which depend on producers directly for nutrition are called Herbivores

(iv) What are the animals which eat any type of food for nutrition called?
Answer:
The animals which eat any type of food for nutrition are called Omnivore

(v) What will happen if one animal in the food chain goes extinct?
Answer:
If one animal in the food chain goes extinct the entire food chain collapse

(vi) What are the factors badly affecting the food web?
Answer:
Factors like hunting, pollution, deforestation, human-animal conflicts etc. are the factors badly affecting the food web

Complete the paragraph

(1) Elemental oxygen is normally found in the form of a diatomic molecule. However, in the upper reaches of the atmosphere, a molecule containing three atoms of oxygen is found. This would mean a formula of 03 and this is called ozone. Unlike the normal diatomic molecule of oxygen, ozone is poisonous and we are lucky that it is not stable nearer to the Earth’s surface. But it performs an essential function where it is found. It absorbs harmful radiations from the Sun. This prevents those harmful radiations from reaching the surface of the Earth where they may damage many forms of life.

Recently it was discovered that this ozone layer was getting depleted. Various man-made compounds like CFCs (carbon compounds having both fluorine and chlorine) which are very stable and not degraded by any biological process) were found to persist in the atmosphere. Once they reached the ozone layer, they would react with the ozone molecules. This resulted in a reduction of the ozone layer and recently they have discovered a hole in the ozone layer above the Antarctica. It is difficult to imagine the consequences for life on Earth if the ozone layer dwindles further, but many people think that it would be better not to take chances. These people advocate working towards stopping all further damage to the ozone layer.

(2) The utilisation of glucose to provide energy to living things involves the process of respiration in which oxygen may or may not be used to convert glucose back into carbon dioxide. This carbon dioxide then goes back into the atmosphere. Another process that adds to the carbon dioxide in the atmosphere is the process of combustion where fuels are burnt to provide energy for various needs like heating, cooking, transportation and industrial processes.

In fact, the percentage of carbon dioxide in the atmosphere is said to have doubled since the industrial revolution when human beings started burning fossil fuels on a very large scale. Carbon, like water, is thus cycled repeatedly through different forms by the various physical and biological activities. Heat is trapped by glass, and hence the temperature inside a glass enclosure will be much higher than the surroundings. This phenomenon was used to create an enclosure where tropical plants could be kept warm during the winters in colder climates. Such enclosures are called greenhouses.

Greenhouses have also lent their name to an atmospheric phenomenon. Some gases prevent the escape of heat from the Earth. An increase in the percentage of such gases in the atmosphere would cause the average temperatures to increase worldwide and this is called the greenhouse effect. Carbon dioxide is one of the greenhouse gases. An increase in the carbon dioxide content in the atmosphere would cause more heat to be retained by the atmosphere and lead to global warming.

(3) Nitrogen gas makes up 78% of our atmosphere and nitrogen is also a part of many molecules essential to life like proteins, nucleic acids (DNA and RNA) and some vitamins. Nitrogen is found in other biologically important compounds such as alkaloids and urea too. Nitrogen is thus an essential nutrient for all life-forms and life would be simple if all these life-forms could use the atmospheric nitrogen directly. However, other than a few forms of bacteria, life-forms are not able to convert the comparatively inert nitrogen molecule into forms like nitrates and nitrites which can be taken up and used to make the required molecules.

These nitrogen-fixing bacteria may be free-living or be associated with some species of dicot plants. Most commonly, the nitrogenfixing bacteria are found in the roots of legumes (generally the plants which give us pulses) in special structures called root nodules. Other than these bacteria, the only other manner in which the nitrogen molecule is converted to nitrates and nitrites is by a physical process. During lightning, the high temperatures and pressures created in the air convert nitrogen into oxides of nitrogen. These oxides dissolve in water to give nitric and nitrous acids and fall on land along with rain. These are then utilised by various lifeforms.

Read the paragraph and answer the questions:

(1) Nitrogen cycle
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification, The majority of Earth’s atmosphere (78%) is atmosphere nitrogen, making it the largest source of nitrogen.

However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems. The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition, Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle. Human modification of the global nitrogen cycle can negatively affect the natural environment system and also human health.

(i) Why nitrogen cycle is called bio-geochemical cycle?
Answer:
Nitrogen cycle is called bio-geochemical cycle as it undergoes biological as well as geochemical processes.

(ii) Why is nitrogen cycle important to us?
Answer:
Nitrogen cycle is important to us as nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition.

(iii) Name important process of nitrogen cycle.
Answer:
Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification.

(iv) What can affect the nitrogen cycle negatively?
Answer:
Human modification of the global nitrogen cycle can negatively affect the natural environment system and also human health.

(v) Which human activities change the nitrogen cycle?
Answer:
Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle.

(2) Food web
A food chain is a linear network of links in a food i web starting from producer organisms (such asgrass or trees which use radiation from the Sun to make their food) and ending at apex predator species (like grizzly bears or killer whales), detritivores (like earthworms or woodlice), ordecomposer species (such as fungi or bacteria), A food chain also shows how the organisms are related with each other by the food they eat. Each level of a food chain represents a different trophiclevel. A food chain differs from a food web, because the complex network of different animal’s feeding relations are aggregated and the chain only follows a direct, linear pathway of one animal at a time.

Natural interconnections between food chains make it a food web. A common metric usedto the quantify food web trophic structure is foodi chain length. In its simplest form, the length of a chain is the number of links between a trophici consumer and the base of the web and the meanchain length of an entire web is the arithmetic average of the lengths of all chains in a food web. The food chain is an energy source diagram. Many food webs have a keystone species. A keystonespecies is a species that has a large impact on thei surrounding environment and can directly affectthe food chain.

If this keystone species dies off it can set the entire food chain off balance. Keystonespecies keep herbivores from depleting all of thei foliage in their environment and preventing ai mass extinction. Food chains were first introduced by the Arab scientist and philosopher Al-Jahiz inthe 10th century and later popularized in a book I published in 1927 by Charles Elton, which also i introduced the food web concept.

(i) What is a food web?
Answer:
Food web is a linear network of links of food chains.

(ii) In a food web which organism are called producers?
Answer:
In a food web which organism which can produce food by photosynthesis are called producers.

(iii) What is the role of keystone species?
Answer:
Keystone species keep herbivores from depleting all of the foliage in their environment and preventing a mass extinction.

(iv) What is a keystone species?
Answer:
A keystone species is a species that has a large impact on the surrounding environment and can directly affect the food chain.

(v) What does each level of food chain represent?
Answer:
Each level of a food chain represents a different trophic level.

(3) Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. Carbon is the main component of biological compounds as well as a major component of many minerals such as limestone. Along with the nitrogen cycle and the water cycle, the carbon cycle comprises a sequence of events that are key to make Earth capable of sustaining life. It describes the movement of carbon as it is recycled and reused throughout the biosphere, as well as long-term processes of carbon sequestration to and release from carbon sinks.

The carbon cycle was discovered by Antoine! Lavoisier and Joseph Priestley, and popularised by Humphry Davy. Carbon in the Earth’satmosphere exists in two main forms carbon dioxide and methane. Both of these gases absorb and retain heat in the atmosphere and are partially responsible for the greenhouse effect. Methane produces a larger greenhouse effect per volume as compared to carbon dioxide, but it exists in much lower concentrations and is more short-lived than carbon dioxide, making carbon dioxide the more important greenhouse gas of the two.

Carbon dioxide is removed from the atmosphere primarily through photosynthesis and enters the terrestrial and oceanic biospheres. Carbon dioxide also dissolves directly from the atmosphere into bodies of water (ocean, lakes, etc.), as well as dissolving in precipitation as raindrops fall through the atmosphere. When dissolved in water, carbon dioxide reacts with water molecules and forms carbonic acid, which contributes to ocean acidity. It can then be absorbed by rocks through weathering. It also can acidify other surfaces it touches or be washed into the ocean.

(i) Which gas has greener house effect as compared to CO₂?
Answer:
Methane gas CH₄ has greener house effect as compared to CO₂.

(ii) How does dissolved CO₂ affect oceans?
Answer:
When dissolved in water, carbon dioxide reacts with water molecules and forms carbonic acid, which contributes to ocean acidity.

(iii) Why is carbon cycle called bio-geochemical cycle?
Answer:
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.

(iv) How is carbon dioxide removed from atmosphere?
Answer:
Carbon dioxide is removed from the atmosphere primarily through photosynthesis and enters the terrestrial and oceanic biospheres.

(v) Who discovered the carbon cycle?
Answer:
The carbon cycle was discovered by Antoine Lavoisier and Joseph Priestley.

Answer the questions in detail:

Question 1.
Write the important processes of the nitrogen cycle.
Answer:

• Nitrogen fixation: Conversion of nitrogen into nitrates and nitrites through atmospheric, industrial and biological processes.
• Ammonification: Release of ammonia through decomposition of dead bodies and excretory wastes of organisms.
• Nitrification: Conversion of ammonia into a nitrite and then nitrate.
• Denitrification: Conversion of nitrogen components into gaseous nitrogen.

Make a concept diagram and explain.

Question 1.
Food chain

Answer:
According to the mode of nutrition the organisms are classified into producers, consumers, saprotrophs (saprophytes) and decomposers. Primary consumers are directly dependent on autotrophs (producers), e.g.: Grasshopper, squirrel, elephant) Secondary consumers use herbivores as their food, e.g.: Frog, owl, fox, etc. Apex or top consumers use herbivores and carnivores as their food. No animals feed on top consumers, e.g.: Tiger, lion, etc. Omnivores feed on herbivores and carnivores, e.g.: Humans, bear, etc. A continuous interaction between producers, consumers and decomposers in a definite sequence is called as food chain.

Food chain, in ecology is the sequence of transfers of matter and energy in the form of food from organism to organism. Food chains intertwine locally into a food web because most organisms consume more than one type of animal or plant. Plants, which convert solar energy to food by photosynthesis, are the primary food source. In a predator chain, a plant-eating animal is eaten by a flesh-eating animal. In a parasite chain, a smaller organism consumes part of a larger host and may itself be parasitized by even smaller organisms. In a saprophytic chain, microorganisms live on dead organic matter.

Question 2.
Energy pyramid
Answer:

An energy pyramid is a model that shows the flow of energy from one trophic, or feeding, level to the next in an ecosystem. The model is a diagram that compares the energy used by organisms at each trophic level. The energy in an energy pyramid is measured in units of kilocalories (kcal). Energy pyramids are similar to biomass pyramids, another type of trophic pyramid that models the amount of biomass at each trophic level in an ecosystem, energy flow in ecosystems. The structure of an energy pyramid reflects the trophic structure of an ecosystem.

The pyramid is divided into trophic levels similar to those in a food chain. At the pyramid base are the producers, autotrophic organisms that make their own food from inorganic substances. All of the other organisms in the energy pyramid are consumers. These are heterotrophs, meaning that they get food energy by consuming other organisms. The consumers at each trophic level feed on organisms from the level below and are themselves consumed by organisms at the level above. Primary consumers are organisms that consume producers; thus, most primary consumers are herbivores, though some may be detrivores (organisms that feed on decaying organic matter).

Secondary consumers are carnivores that feed on primary consumers and tertiary consumers are carnivores that eat secondary consumers. In rare instances, an ecosystem may have an additional trophic level composed of quaternary consumers camivores that consume tertiary consumers’ energy pyramid. The shape of an energy pyramid shows that the amount of food energy that enters each trophic level is less than the amount that entered the level below. Approximately 90 percent of the food energy that enters a trophic level is “lost” as heat when it is used by organisms to power the normal activities of life such as breathing and digesting food the remaining 10 percent is stored in the various organisms’ tissues.

It is this latter energy that is available to be passed to the next trophic level. Thus, the higher the trophic level on the pyramid, the lower the amounts of available energy ecosystem energy transfer through an ecosystem. The number of organisms at each level decreases relative to the level below because there is less energy available to support those organisms. The top level of an energy pyramid has the fewest organisms because it has the least amount of energy. Eventually there is not enough energy left to support another trophic level; thus most ecosystems only have four trophic levels.

Read More:

DALBHARAT Pivot Point Calculator

Balbharti Maharashtra State Board Class 10 Maths Solutions covers the Practice Set 2.3 Algebra 10th Class Maths Part 1 Answers Solutions Chapter 2 Quadratic Equations.

Practice Set 2.3 Algebra 10th Std Maths Part 1 Answers Chapter 2 Quadratic Equations

Question 1.
Solve the following quadratic equations by completing the square method.
1. x² + x – 20 = 0
2. x² + 2x – 5 = 0
3. m² – 5m = -3
4. 9y² – 12y + 2 = 0
5. 2y² + 9y + 10 = 0
6. 5x² = 4x + 7
Solution:
1. x² + x – 20 = 0
If x² + x + k = (x + a)², then
x² + x + k = x² + 2ax + a²
Comparing the coefficients, we get
1 = 2a and k = a²

∴ The roots of the given quadratic equation are 4 and -5.

2. x² + 2x – 5 = 0
If x² + 2x + k = (x + a)², then
x² + 2x + k = x² + 2ax + a²
Comparing the coefficients, we get
2 = 2a and k = a²
∴ a = 1 and k = (1)² = 1
Now, x² + 2x – 5 = 0
∴ x² + 2x + 1 – 1 – 5 = 0
∴ (x + 1)² – 6 = 0
∴ (x + 1)² = 6
Taking square root of both sides, we get
x + 1 = ± √6
∴ x + 1 √6 or x + 1 = √6
∴ x = √6 – 1 or x = -√6 – 1
∴ The roots of the given quadratic equation are √6 -1 and – √6 -1.

3. m² – 5m = -3
∴ m² – 5m + 3 = 0
If m² – 5m + k = (m + a)², then
m² – 5m + k = m² + 2am + a²
Comparing the coefficients, we get
-5 = 2a and k = a²

4. 9y² – 12y + 2 = 0

5. 2y² + 9y + 10 = 0

Taking square root of both sides, we get

∴ The roots of the given quadratic equation are -2 and \(\frac { -5 }{ 2 } \).

6. 5x² = 4x + 7
∴ 5x² – 4x – 7 = 0

Comparing the coefficients, we get

Balbharti Maharashtra State Board Class 9 Maths Solutions covers the Practice Set 3.6 Algebra 9th Class Maths Part 1 Answers Solutions Chapter 3 Polynomials.

Practice Set 3.6 Algebra 9th Std Maths Part 1 Answers Chapter 3 Polynomials

Question 1.
Find the factors of the polynomials given below:
i. 2x² + x – 1
ii. 2m² + 5m – 3
iii. 12x² + 61x + 77
iv. 3y² – 2y – 1
v. √3x² + 4x + √3
vi. \(\frac { 1 }{ 2 }\)x² – 3x + 4
Solution:
i. 2x² + x – 1
= 2x² + 2x – x – 1
= 2x(x + 1)- 1(x + 1)
= (x + 1)(2x – 1)

ii. 2m² + 5m – 3
= 2m² + 6m – m – 3
= 2m(m + 3) – 1(m + 3)
= (m + 3)(2m – 1)

iii. 12x² + 61x + 77
= 12x² + 28x + 33x + 77
= 4x(3x + 7) 4 + 11(3x + 7)
= (3x + 7)(4x + 11)

iv. 3y² – 2y – 1
= 3y² – 3y + y – 1
= 3y(y – 1) + 1 (y – 1)
= (y – 1)(3y + 1)

v. √3×2 + 4x + √3
= √3×2 + 3x + x + √3
= √3×2 + √3 x √3x + x + √3
= √3x(x + √3) + 1 ( x + √3 )
= (x + √3)(√3x + 1)

vi. \(\frac { 1 }{ 2 }\) x² – 3x + 4
= \(\frac { 1 }{ 2 }\) x² – 2x – x + 4
= \(\frac{1}{2} x^{2}-\frac{2 \times 2}{2} x-x+4\)
= \(\frac { 1 }{ 2 }\) x(x – 4) – 1 (x – 4)
= (x – 4) (\(\frac { 1 }{ 2 }\) x – 1)

Alternate method
\(\frac { 1 }{ 2 }\) x² – 3x + 4 = \(\frac { 1 }{ 2 }\) (x² – 6x + 8)
= \(\frac { 1 }{ 2 }\) (x² – 4x – 2x + 8)
= \(\frac { 1 }{ 2 }\) [x(x – 4) – 2(x – 4)]
= \(\frac { 1 }{ 2 }\) (x – 2)(x – 4)

Question 2.
Factorize the following polynomials.
i. (x² – x)² – 8(x² – x) + 12
iii. (x² – 6x)² – 8(x² – 6x + 8) – 64
v. (y + 2) (y – 3) (y + 8) (y + 3) + 56
vii. (x – 3) (x – 4)² (x – 5) – 6
Solution:
i. (x² – x)² – 8(x² – x) + 12
= m² – 8m + 12 …[Putting x² – x = m]
= m² – 6m – 2m + 12
= m(m – 6) – 2(m – 6)
= (m – 6)(m – 2)
= (x² – x- 6) (x² – x- 2) …[Replacing m = x² -x]
= (x² – 3x + 2x – 6) (x² – 2x + x – 2)
= [x(x – 3) + 2(x – 3)] [x(x – 2) + 1 (x-2)]
= (x – 3) (x + 2) (x – 2) (x + 1)

ii. (x – 5)² – (5x – 25) – 24
= (x – 5)² – (5x – 25) – 24
= (x – 5)² – 5(x – 5) – 24
= m² – 5m – 24 … [Putting x – 5 = m]
= m² – 8m + 3m – 24
= m(m – 8) + 3(m – 8)
= (m – 8) (m + 3)
= (x – 5 – 8) (x – 5 + 3) … [Replacing m = x – 5]
= (x – 13) (x – 2)

iii. (x² – 6x)² – 8(x² – 6x + 8) – 64
= m² – 8(m + 8)-64 …[Putting x² – 6x = m]
= m² – 8m – 64 – 64
= m² – 8m – 128
= m² – 16m + 8m- 128
= m(m – 16) + 8(m – 16)
= (m – 16)(m + 8)
= (x² – 6x – 16) (x² – 6x + 8) … [Replacing m = x² – 6x]
= (x² – 8x + 2x – 16) (x² – 4x – 2x + 8)
= [x(x – 8) + 2(x – 8)] [x(x – 4) – 2(x – 4)]
= (x – 8) (x + 2) (x – 4) (x – 2)

iv. (x²– 2x + 3) (x² – 2x + 5) – 35
= (m + 3) (m + 5) – 35 … [Putting x² – 2x = m]
= m (m + 5) + 3(m + 5) – 35
= m² + 5m + 3m + 15 – 35
= m² + 8m – 20
= m² + 10m – 2m – 20
= m(m + 10) – 2(m + 10)
= (m + 10) (m – 2)
= (x² – 2x + 10) (x² – 2x – 2) … [Replacing m = x² – 2x]

v. (y + 2) (y – 3) (y + 8) (y + 3) + 56
= (y + 2)(y + 3)(y – 3)(y + 8) + 56
= (y² + 3y + 2y + 6) (y² + 8y – 3y – 24) + 56
= (y² + 5y + 6) (y² + 5y – 24) + 56
= (m + 6) (m – 24) + 56 … [Putting y2 + 5y = m]
= m (m – 24) + 6 (m – 24) + 56
= m² – 24m + 6m – 144 + 56
= m² – 18m – 88
= m² – 22m + 4m – 88
= m(m – 22) + 4(m – 22)
= (m – 22) (m + 4)
= (y² + 5y – 22)(y² + 5y + 4) … [Replacing m = y² + 5y]
= (y² + 5y – 22) (y² + 4y + y + 4)
= (y² + 5y – 22) [y(y + 4) + 1(y + 4)]
= (y² + 5y – 22) (y + 4) (y + 1)

vi. (y² + 5y) (y² + 5y – 2) – 24
= (m)(m – 2) – 24 … [Putting y² + 5y = m]
= m² – 2m – 24
= m² – 6m + 4m – 24
= m(m – 6) + 4(m – 6)
= (m – 6) (m + 4)
= (y² + 5y – 6) (y² + 5y + 4) … [Replacing m = y² + 5y]
= (y² + 6y – y – 6) (y² + 4y + y + 4)
= [y(y + 6) – 1(y + 6)] [y(y + 4) + 1(y + 4)]
= (y + 6) (y – 1) (y + 4) (y + 1)

vii. (x – 3) (x – 4)2 (x – 5) – 6
= (x – 3) (x – 5) (x – 4)² – 6
= (x² – 5x – 3x + 15) (x² – 8x + 16) – 6
= (x² – 8x + 15) (x² – 8x + 16) – 6
= (m + 15) (m+ 16) – 6 … [Putting x² – 8x = m]
= m (m + 16) + 15 (m + 16) – 6
= m² + 16m + 15m + 240 – 6
= m² + 31m + 234
= m² + 18m + 13m + 234
= m(m + 18) + 13(m + 18)
= (m + 18) (m + 13)
= (x² – 8x + 18) (x² – 8x + 13) … [Replacing m = x² – 8x]

Balbharti Maharashtra Board Class 5 Maths Solutions Chapter 16 Preparation for Algebra Problem Set 55 Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 5 Maths Solutions Chapter 16 Preparation for Algebra Problem Set 55

Question 1.
Say whether right or wrong.

(1) (23 + 4) = (4 + 23)
Answer:
27 = 27 is right

(2) (9 + 4) > 12
Answer:
13 > 12 is right

(3) (9 + 4) < 12
Answer:
13 < 12 is wrong

(4) 138 > 138
Answer:
Wrong

(5) 138 < 138
Answer:
Wrong

(6) 138 = 138
Answer:
right

(7) (4 × 7) = 30 – 2
Answer:
28 = 28 is right

(8) \(\frac{25}{5}\) > 5
Answer:
5 > 5 is wrong.

(9) (5 × 8) = (8 × 5)
Answer:
40 = 40 is right

(10) (16 + 0) = 0
Answer:
16 + 0
= 16
16 = 0 is wrong

(11) (16 + 0) = 16
Answer:
16 = 16 is right.

(12) (9 + 4) = 12
Answer:
13 = 12 is wrong.

Question 2.
Fill in the blanks with the right symbol from <, > or =.

(1) (45 ÷ 9) [ ] (9 – 4)
Answer:
45 ÷ 9 = 5,
9 – 4 = 5 5
= 5
so, (45 + 9) = (9 – 4)

(2) (6 + 1) [ ] (3 × 2)
Answer:
6 + 1 = 7,
3 x 2 = 6
7 > 6
so, (6 + 1) > (3 x 2)

(3) (12 × 2) [ ] (25 + 10)
Answer:
12 x 2 = 24,
25 + 10 = 35
24 < 35
so, (12 x 2) < (25 + 10)

Question 3.
Fill in the blanks in the expressions with the proper numbers.

(1) (1 × 7) = ( [ ] × 1)
Answer:
1 x 7 = 7,
7 x 1 = 7
so, (1 x 7) = ( 7 x 1)

(2) (5 × 4) > (7 × [ ] )
Answer:
5 x 4 = 20, 7 x ………… must be less than 20.
7 x 2 = 14
so, (5 x 4) > ( 7 x 2)

(3) (48 ÷ 3) < ( [ ] × 5)
Answer:
48 – 3 = 16,
5 x 4 = 20
5 x 3 = 15
16 > 15 and 16 < 20 so, (48 + 3) <(4 x 5)

(4) (0 + 1) > (5 × [ ] )
Answer:
0 + 1 = 1,
5 x 1 = 5
5 x 0 = 0
1 < 5 and 1 > 0 so, (0 + 1) > (5 x Q)

(5) (35 ÷ 7) = ( [ ] + [ ] )
Answer:
35 ÷ 7 = 5,
3 + 2 = 5 so, (35 + 7) = (3 + 2)

(6) (6 – [ ] ) < (2 + 3)
Answer:
6 – < 2 + 3 = 5
5 > 6 – 2
so, (6 – 2) < (2 + 3)

Using letters
Symbols are frequently used in mathematical writing. The use of symbols makes the writing very short. For example, using symbols, ‘Division of 75 by 15 gives us 5’ can be written in short as ‘75 ÷ 15 = 5’. It is also easier to grasp.

Letters can be used like symbols to make our writing short and simple.

While adding, subtracting or carrying out other operations on numbers, you must have discovered many properties of the operations.

For example, what properties do you see in sums like (9 + 4), (4 + 9)?

The sum of any two numbers and the sum obtained by reversing the order of the two numbers is the same.

Now see how much easier and faster it is to write this property using letters.

• Let us use a and b to represent any two numbers. Their sum will be ‘a + b’.

Changing the order of those numbers will make the addition ‘b + a’. Therefore, the rule will be : ‘For all values of a and b, (a + b) = (b + a).’

Let us see two more examples.

• Multiplying any number by 1 gives the number itself. In short, a × 1 = a.
• Given two unequal numbers, the division of the first by the second is not the same as the division of the second by the first.

In short, if a and b are two different numbers, then (a ÷b) ≠ (b ÷a).

Take the value of a as 8 and b as 4 and verify the property yourself.

Preparation for Algebra Problem Set 54 Additional Important Questions and Answers

Say whether right or wrong.

(1) (15 ÷ 3) =5
Answer:
5 = 5 is right.

(2) (2 x 1) = 1
Answer:
2 = 1 is wrong.

(3) (16 ÷ 8) = (2 x 2)
Answer:
2 = 4 is wrong.

(4) (13 – 7) = 6
Answer:
6 = 6 is right.

(5) (1 x 0) = 1
Answer:
1 = 1 is wrong.

(6) (1 + 0) = 1
Answer:
1 = 1 is right.

Fill in the blanks with the right symbol from <, >, or =.

(1) (12 + 6) (10 X 2)
Answer:
12 + 6 = 18,
10 x 2 = 20
18 < 20
so, (12 + 6) < (10 x 2)

(2) (4 X 5) (10 X 2)
Answer:
4 x 5 = 20,
10 x 2 = 20
20 = 20
so, (4 x 5) = (10 x 2)

(3) (7 + 3) ………….. (3 X 3)
Answer:
7 + 3 = 10,
3 x 3 = 9
10 > 9
so, (7+ 3) > (3 x 3)

Fill in the blanks in the expressions with the proper numbers.

(1) (8 + ………….. ) = (8 x 1)
Answer:
8 + ……………. = 8,
8 x 1 = 8
8 + 0 = 8
so, (8 + 0) = (8 x 1)

(2) (5 x 6) > (14 x ……….. )
Answer:
5 x 6 = 30,
14 x 1 = 14
14 x 2 = 28
14 x 3 = 42
30 >28
so, (5 x 6) >(14 x 2)

(3) (6 X 7) < ( x 5)
Ans.
6 x 7 = 42,
9 x 5 = 45
42 < 45, 50, 55
so, (6 x 7) < (9 x 5)

Balbharti Maharashtra Board Class 5 Maths Solutions Chapter 16 Preparation for Algebra Problem Set 56 Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 5 Maths Solutions Chapter 16 Preparation for Algebra Problem Set 56

Question 1.
Use a letter for ‘any number’ and write the following properties in short.

(1) The sum of any number and zero is the number itself.
Answer:
a + 0 = a

(2) The product of any two numbers and the product obtained after changing the order of those numbers is the same.
Answer:
a x b = b x a

(3) The product of any number and zero is zero.
Answer:
a x 0 = 0

Question 2.
Write the following properties in words :

(1) m – 0 = m
Answer:
Subtracting zero from any number, gives the number itself.

(2) n ÷ 1 = n
Answer:
Dividing any number by 1, gives the number itself.

Preparation for Algebra Problem Set 56 Additional Important Questions and Answers

Use a letter for any number and write the following properties in short.

Question 1.
The product of any number and 1 is the number itself.
Answer:
a x 1 = a

Question 2.
The division of any two different numbers and the divisions obtained after changing the order of those numbers is not the same.
Answer:
a ÷ b ≠ b + a

Write the following properties in words:

Question 1.
p x 0 = 0
Answer:
The product of any number and zero is zero.

(4) a + b = b + a
Answer:
The sum of any two numbers and the sum obtained after changing the order of these numbers is the same.

Using brackets write three pairs of numbers whose

(1) Sum is 9
Answer:
5 + 4 = 9,
7 + 2 = 9,
8 + 1 = 9

(2) difference is 9
Answer:
12 – 3 = 9,
11 – 2 = 9,
10 – 1 = 9

(3) multiplication is 16 and
Answer:
4 x 4 = 16,
8 x 2 = 16,
16 x 1 = 16

(4) division is 16.
Answer:
32 ÷ 2 = 16,
48 ÷ 3 = 16,
64 ÷ 4 = 16,

Fill in the blanks.

(1) 4 + 2 = 7 – ……….
(2) 4 + 2 = 3 x ……….
(3) 4 + 2 = 12 ÷ ……….
Answer:
(1) 1
(2) 2
(3) 2

Match the columns:

(A)

A		B
(i)	8 + 6	(a)	6 x 2
(2)	9 + 3	(b)	6 + 2
(3)	5 + 1	(c)	16 – 2
(4)	10 – 2	(d)	12 + 2

Answer:
(1 – c),
(2 – a),
(3-d),
(4-b)

(B)

A	B
(1) a – b and b – a	(a) 0
(2) a x b and b x a	(b) 1
(3) a x 0	(c) =
(4) a + a	(d) ≠

Answer:
(1-d),
(2 – c),
(3 – a),
(4 – b)

Say whether right or wrong.

(1) (6 + 5) = (5 + 6)
(2) (8 + 5) > 10
(3) (8 + 5) < 10
(4) 108 > 108
(5) 108 = 108
(6) 108 < 108
(7) (6 x 3) = (20 – 2)
(8) 40 + 8 > 5
(9) (3 x 7) = (7 x 3)
(10) (5 + 0) = (5 x 1)
(11) (6 + 5) = 10
(12) (30 + 5) < (30 – 25)
Answer:
Right : (1), (2), (5), (7), (9), (10)
Wrong : (3), (4), (6), (8), (11), (12)

Fill in the blanks with the right symbol from <, > or =

(1) (24 ÷ 5) ……… (9 – 5)
(2) (4 + 2) ……… (5 x 1)
(3) (7 x 3) ……… (20 + 2)
(4) (8 x 2) (5 x 3)
(5) (5 x 6) ……… (25 + 5)
(6) (6 x 7) (9 x 5)
Answer:
(1) =
(2) >
(3) <
(4) >
(5) =
(6) <

Fill in the blanks in the expressions with the proper numbers.

(1) (4 x 4) = (………. x 2)
(2) (2 x 7) > (4 x ……….)
(3) (30 + 5) < ( x 3)
(4) (5 + 0)> (4 x ……….)
(5) (36 +3) = ( + )
(6) (9 – ……….) < (4 + 1)
(7) (8 + 9) < (3 x ……….)
(8) (0 + 3) > (4 x ……….)
(9) (28 ÷ 2) = (7 x ……….)
Answer:
(1) 8
(2) 3
(3) 9
(4) 1
(5) 7 + 5
(6) 5,
(7) 6
(8) 0
(9) 2

Use a letter for any number and write the following properties in short:

(1) Dividing zero by any non zero number is zero.
Answer:
0 + a = 0

(2) The difference of any two different numbers and the difference obtained after changing the order of those numbers is not same.
Answer:
a – b ≠ b – a

(3) Dividing non zero number by itself gives us 1.
Answer:
a ÷ a = 1

Write the followîng properties in words:

(1) a x 1 = a
Answer:
The product of any number and 1 is the number itself.

(2) a – a = 0
Answer:
Difference of the same two numbers is zero.

Balbharti Maharashtra State Board Class 9 Maths Solutions covers the Practice Set 9.1 Geometry 9th Class Maths Part 2 Answers Solutions Chapter 9 Surface Area and Volume.

Practice Set 9.1 Geometry 9th Std Maths Part 2 Answers Chapter 9 Surface Area and Volume

Question 1.
Length, breadth and height of a cuboid shape box of medicine is 20 cm, 12 cm and 10 cm respectively. Find the surface area of vertical faces and total surface area of this box.
Given: For cuboid shape box of medicine,
length (l) = 20 cm, breadth (b) = 12 cm and height (h) = 10 cm.
To find: Surface area of vertical faces and total surface area of the box
Solution:
i. Surface area of vertical faces of the box
= 2(l + b) x h
= 2(20+ 12) x 10
= 2 x 32 x 10
= 640 sq.cm.

ii. Total surface area of the box
= 2 (lb + bh + lh)
= 2(20 x 12+ 12 x 10 + 20 x 10)
= 2(240 + 120 + 200)
= 2 x 560
= 1120 sq.cm.
∴ The surface area of vertical faces and total surface area of the box are 640 sq.cm, and 1120 sq.cm, respectively.

Question 2.
Total surface area of a box of cuboid shape is 500 sq.unit. Its breadth and height is 6 unit and 5 unit respectively. What is the length of that box?
Given: For cuboid shape box,
breadth (b) = 6 unit, height (h) = 5 unit Total surface area = 500 sq. unit.
To find: Length of the box (l)
Solution:
Total surface area of the box = 2 (lb + bh + lh)
∴ 500 = 2 (6l + 6 x 5 + 5l)
∴ \(\frac { 500 }{ 2 }\) = (11l + 30)
∴ 250= 11l + 30
∴ 250 – 30= 11l
∴ 220 = 11l
∴ 220 = l
∴ \(\frac { 220 }{ 11 }\) = l
∴ l = 20 units
∴ The length of the box is 20 units.

Question 3.
Side of a cube is 4.5 cm. Find the surface area of all vertical faces and total surface area of the cube.
Given: Side of cube (l) = 4.5 cm
To find: Surface area of all vertical faces and the total surface area of the cube
Solution:
i. Area of vertical faces of cube = 4l²
= 4 (4.5)² = 4 x 20.25 = 81 sq.cm.
ii. Total surface area of the cube = 6l²
= 6 (4.5)²
= 6 x 20.25
= 121.5 sq.cm.
∴ The surface area of all vertical faces and the total surface area of the cube are 81 sq.cm, and 121.5 sq.cm, respectively.

Question 4.
Total surface area of a cube is 5400 sq. cm. Find the surface area of all vertical faces of the cube.
Given: Total surface area of cube = 5400 sq.cm.
To find: Surface area of all vertical faces of the cube
Solution:
i. Total surface area of cube = 6l²
∴ 5400 = 6l²
∴ \(\frac { 5400 }{ 6 }\) = l²
∴ l² = 900
ii. Area of vertical faces of cube = 4l²
= 4 x 900 = 3600 sq.cm.
∴ The surface area of all vertical faces of the cube is 3600 sq.cm.

Question 5.
Volume of a cuboid is 34.50 cubic metre. Breadth and height of the cuboid is 1.5 m and 1.15 m respectively. Find its length.
Given: Breadth (b) = 1.5 m, height (h) = 1.15 m
Volume of cuboid = 34.50 cubic metre
To find: Length of the cuboid (l)
Solution:
Volume of cuboid = l x b x h
∴ 34.50 = l x b x h
∴ 34.50 = l x 1.5 x 1.15

= 20
∴ The length of the cuboid is 20 m.

Question 6.
What will be the volume of a cube having length of edge 7.5 cm ?
Given: Length of edge of cube (l) = 7.5 cm
To find: Volume of a cube
Solution:
Volume of a cube = l²
= (7.5)³
= 421.875 ≈ 421.88 cubic cm
∴The volume of the cube is 421.88 cubic cm.

Question 7.
Radius of base of a cylinder is 20 cm and its height is 13 cm, find its curved surface area and total surface area, (π = 3.14)
Given: Radius (r) = 20 cm, height (h) = 13 cm
To find: Curved surface area and
the total surface area of the cylinder
Solution:
i. Curved surface area of cylinder = 2πrh
= 2 x 3.14 x 20 x 13
= 1632.8 sq.cm

ii. Total surface area of cylinder = 2πr(r + h)
= 2 x 3.14 x 20(20 + 13)
= 2 x 3.14 x 20 x 33 = 4144.8 sq.cm
∴ The curved surface area and the total surface area of the cylinder are 1632.8 sq.cm and 4144.8 sq.cm respectively.

Question 8.
Curved surface area of a cylinder is 1980 cm² and radius of its base is 15 cm. Find the height of the cylinder. (π = \(\frac { 22 }{ 7 }\))
Given: Curved surface area of cylinder = 1980 sq.cm., radius (r) = 15 cm
To find: Height of the cylinder (h)
Solution:
Curved surface area of cylinder = 2πrh
∴ 1980 = 2 x \(\frac { 22 }{ 7 }\) x 15 x h
∴ \(h=\frac{1980 \times 7}{2 \times 22 \times 15}\)
∴ h = 21 cm
∴ The height of the cylinder is 21 cm.

Balbharti Maharashtra State Board Class 10 Maths Solutions covers the Practice Set 7.4 Geometry 10th Class Maths Part 2 Answers Solutions Chapter 7 Mensuration.

Practice Set 7.4 Geometry 10th Std Maths Part 2 Answers Chapter 7 Mensuration

Practice Set 7.4 Geometry Class 10 Question 1. In the adjoining figure, A is the centre of the circle. ∠ABC = 45° and AC = 7\(\sqrt { 2 }\) cm. Find the area of segment BXC, (π = 3.14)

Solution:
In ∆ABC,
AC = AB … [Radii of same circle]
∴ ∠ABC = ∠ACB …[Isosceles triangle theorem]
∴ ∠ABC = ∠ACB = 45°
In ∆ABC,
∠ABC + ∠ACB + ∠BAC = 180° … [Sum of the measures of angles of a triangle is 180° ]
∴ 45° + 45° + ∠BAC = 180°
∴ 90° + ∠BAC = 180°
∴ ∠BAC = 90°
Let ∠BAC = θ = 90°

∴ The area of segment BXC is 27.93 cm².

10th Class Geometry Practice Set 7.4 Question 2. In the adjoining figure, O is the centre of the circle.
m(arc PQR) = 60°, OP = 10 cm. Find the area of the shaded region.
(π = 3.14, \(\sqrt { 3 }\) = 1.73)

Given: m(arc PQR) = 60°, radius (r) = OP = 10 cm
To find: Area of shaded region.
Solution:
∠POR = m (arc PQR) …[Measure of central angle]
∴ ∠POR = θ = 60°


∴ The area of the shaded region is 9.08 cm².

7.4 Class 10 Question 3. In the adjoining figure, if A is the centre of the circle, ∠PAR = 30°, AP = 7.5, find the area of the segment PQR. (π = 3.14)

Given: Central angle (θ) = ∠PAR = 30°,
radius (r) = AP = 7.5
To find: Area of segment PQR.
Solution:
Let ∠PAR = θ = 30°

∴ The area of segment PQR is 0.65625 sq. units.

Chapter 7 Maths Class 10 Question 4. In the adjoining figure, if O is the centre of the circle, PQ is a chord, ∠POQ = 90°, area of shaded region is 114 cm2, find the radius of the circle, (π = 3.14)

Given: Central angle (θ) = ∠POQ= 90°,
A (segment PRQ) = 114 cm²
To find: Radius (r).
Solution:

…[Taking square root of both sides]
∴ r = 20 cm
∴ The radius of the circle is 20 cm.

Mensuration Questions for Class 10 Question 5. A chord PQ of a circle with radius 15 cm subtends an angle of 60° with the centre of the circle. Find the area of the minor as well as the major segment. (π = 3.14, \(\sqrt { 3 }\) = 1.73)
Given: Radius (r) =15 cm, central angle (θ) = 60°
To find: Areas of major and minor segments.
Solution:
Let chord PQ subtend ∠POQ = 60° at centre.
∴ θ = 60°

= 225 [0.0908]
= 20.43 cm²
∴ area of minor segment = 20.43 cm²
Area of circle = πr²
= 3.14 × 15 × 15
= 3.14 × 225
= 706.5 cm²
Area of major segment
= Area of circle – area of minor segment
= 706.5 – 20.43
= 686.07 cm²
Area of major segment 686.07 cm²
∴ The area of minor segment Is 20.43 cm² and the area of major segment is 686.07 cm².

Balbharti Maharashtra State Board Class 6 Maths Solutions covers the Std 6 Maths Chapter 18 Three Dimensional Shapes Class 6 Practice Set 41 Answers Solutions.

6th Standard Maths Practice Set 41 Answers Chapter 18 Three Dimensional Shapes

Question 1.
Write the number of faces, edges and vertices of each shape in the table.

Solution:

Name	Cylinder	Cone	Pentagonal pyramid	Hexagonal pyramid	Hexagonal prism	Pentagonal prism
Faces	3 (2 flat + 1 curved)	2 (1 flat + 1 curved)	6 (5 triangles + 1 pentagon)	7 (6 triangles + 1 hexagon)	8 (6 rectangles + 2 hexagons)	7 (5 rectangles + 2 pentagons)
Vertices	0	1	6	7	12	10
Edges	2 (circular)	1 (circular)	10	12	18	15

Maharashtra Board Class 6 Maths Chapter 18 Three Dimensional Shapes Practice Set 41 Questions and Activities

Question 1.

1. Take a rectangular sheet.
2. Bring together its opposite sides. What shape does it form? (Textbook pg. no. 94)

Solution:
It forms a hollow cylinder.

Question 2.

1. Take a cylindrical tin.
2. Take a rectangular sheet with one side equal to the height of the tin.
3. Wrap it around the tin to cover it completely and cut away the extra paper.
4. Then unfold it and spread it out on a table.
5. Take another sheet. Place the tin on it and draw its circular outline.
6. Cut away the paper around it. Cut out another circle like this one.
7. Place these discs next to the rectangular paper as shown in the given figure. Which figure is obtained? (Textbook pg. no. 94)

Solution:
The figure obtained is the net of the closed cylinder.

Question 3.
Can you tell? (Textbook pg. no. 95)
When playing carom, you make a pile of the pieces as shown in the picture. What is the shape of this pile?
If you place a number of CD’s or round biscuits one on top of the other, what shape do you get?

Solution:
In all the cases, it will form a cylindrical shape (2 circular faces and 1 curved surface).

Question 4.

1. Draw a net as shown in figure (a) on a card sheet and cut it out.
2. Fold along the dotted lines of the square and bring the sides together so that the vertices A, B, C and D meet at a point.

What shape does it form? (Textbook pg. no. 95)

Solution:
The given net forms a quadrangular pyramid.

Question 5.

1. Draw a net as shown in figure (a) on a card sheet and cut it out.
2. Fold along the dotted lines of the triangle and bring the sides together so that the vertices A, B and C meet at a point.

What shape does it form? (Textbook pg. no. 95)

Solution:
The given net forms a triangular pyramid.

Question 6.

1. Using a compass draw a circle with centre C on a paper.
2. Draw two radii CR and CS.
3. Cut out the circle.
4. Cut along the radii and obtain two pieces of the circle.
5. Bring together the sides CR and CS of each piece.

On completing the activity, what shapes did you get? (Textbook pg. no. 95)

Solution:
On completing the activity, we get an open cone.

Read Also:

• Shapes Worksheets