Maharashtra Board Class 11 Biology Important Questions Chapter 14 Human Nutrition

Balbharti Maharashtra State Board 11th Biology Important Questions 14 Human Nutrition Important Questions and Answers.

Maharashtra State Board 11th Biology Important Questions Chapter 14 Human Nutrition

Question 1.
Explain various steps involved in nutrition.
Answer:
The various steps involved in nutrition are as follows:

1. Ingestion: It is the introduction of food into the mouth, i.e. intake of food (eating) inside the body.
2. Digestion: The process during which the complex, non-diffusible and non-absorbable food substances are converted into simple, diffusible, and absorbable substances by the action of enzymes is called digestion.
3. Absorption: The process of diffusion of digested food into blood and lymph is called absorption.
4. Assimilation: The process by which protoplasm is synthesized into each cell of the body by utilizing simple food substances is called assimilation.
5. Egestion: The elimination of undigested food from the body is called egestion.

Question 2.
What are the dietary needs of human being?
Answer:
Carbohydrates, proteins, fats, vitamins, minerals, water and fibres in adequate amount are the dietary needs of human being.

Question 3.
Fill in the blanks:
i. Food provides _________ for growth and tissue repair.
ii. ________ are also required in small quantities for nutrition.
Answer:
i. energy, organic material.
ii. Vitamins, minerals.

Question 4.
Define: Digestion
Answer:
Digestion is defined as the process by which the complex, non-diffusible and non-absorbable food substances are converted into simple, diffusible and assimilable substances.

Question 5.
What is dentition?
Answer:
The study of teeth with respect to their number, arrangement, development etc. is known as dentition.

Question 6.
Describe the structure and functions of the various parts of the alimentary canal.
Answer:
Human Digestive system:
Human digestive system consists of alimentary canal and associated digestive glands.
Alimentary canal:
Alimentary canal is a long tube-like structure of varying diameter starting from mouth and ending with anus. It is about 8-10m long.
Alimentary canal consists of mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine, large intestine and anus.
Mouth:

• It is also called oral or buccal cavity and is bounded by fleshy lips.
• Its side walls are formed of cheeks, roof is formed by palate and floor by tongue.
• It is internally lined by a mucous membrane.
• Salivary glands open into the buccal cavity.

Function: It helps in ingestion of food.

Teeth:

• 32 teeth are present in the buccal cavity of an adult human being.
• Human dentition is described as thecodont, diphyodont and heterodont.
• It is called thecodont type because each tooth is fixed in a separate socket present in jaw bones by gomphosis type of joint.
• In our life time, we get only two sets of teeth, milk teeth and permanent teeth. This is called diphyodont dentition.
• We have four different type of teeth hence we are heterodont.
• Types of teeth are incisors (I) canines (C) premolars (PM) and molar (M).
• Each half of each jaw has two incisors, one canine, two premolars and three molars.
• Thus, dental formula of adult human can be represented as:
  i\(\frac{2}{2}\), c\(\frac{1}{1}\), pm\(\frac{2}{2}\), m\(\frac{3}{3}\) = \(\frac{8}{8}\) = 16 × 2 = 32

Tongue:
It is the muscular fleshy organ and is roughly triangular in shape. It lies along the floor of the buccal cavity.

Functions: The upper surface of the tongue bears numerous projections called papillae.
These papillae contain sensory receptors called taste buds.

ii. Pliary nx:

• The buccal cavity leads to a short pharynx.
• Pharynx is a common passage for food and air.
• The pharynx opens into trachea through an opening called glottis.
• The glottis is guarded by a cartilaginous flap called epiglottis. The epiglottis closes during the swallowing (deglutition) action and pre vents entry of food into the trachea.
• The lower region of pharynx is called oropharynx.
• Oropharynx opens into oesophagus through gullet.

iii. Oesophagus:

• The oesophagus is a thin, muscular tube.
• It lies behind the trachea.
• It is approximately 25cm long tube passes through the neck, central aspect of rib cage, pierces the diaphragm and joins the stomach.
• It is lined by mucus cells.
• Mucus lubricates the passageway of food.
• Oesophagus is made up of longitudinal and circular muscles.

Function: The rhythmic wave of contraction and relaxation of these muscles is called peristalsis that helps in passage of food through oesophagus.

iv. Stomach:
The stomach is located in the upper left portion of the abdominal cavity.
It is a muscular sac-like ‘J1 shaped organ, around 25 to 30cm in length.
It is divided into upper cardiac region and lower pyloric region.

• Cardia or Cardiac: It is first part in which oesophagus opens. The cardia surrounds the band of circular muscles present at the junction of oesophagus and stomach called cardiac sphincter. The cardiac sphincter prevents back flow or regurgitation of food from stomach to oesophagus.
• Fundus: It is the dome shaped region above and left of cardia.
• Body: It forms the large central portion of stomach that stores the food.
• Pylorus: It is a narrow posterior region of stomach.
  It opens into duodenum, the initial part of small intestine.
  This opening is guarded by a set of sphincter muscles called pyloric sphincter.
  It regulates the flow of food from stomach to small intestine.

Function: The stomach temporarily stores the food.
It chums the food and helps in mixing the food with gastric juice.

v. Small Intestine:

• It is about 6 meters long and 2.5 cm broad tube coiled within abdominal cavity.
• The coils are held together by mesenteries, supporting the blood vessels, lymph vessels and nerves.
• It is divided into three parts: Duodenum, jejunum and ileum.

vi. Large Intestine:

• It is 1.5 meters in length.
• It is wider in diameter and shorter than small intestine.
• It consists of caecum, colon and rectum.

vii. Anus:

• Anus is the terminal opening of alimentary canal.
• It is guarded by sphincter.

Function: It expels faecal matter by a process called egestion or defecation.

Question 7.
Draw a neat and labelled diagram of stomach and write a short note on it.
Answer:
Stomach:
The stomach is located in the upper left portion of the abdominal cavity.
It is a muscular sac-like ‘J1 shaped organ, around 25 to 30cm in length.
It is divided into upper cardiac region and lower pyloric region.

1. Cardia or Cardiac: It is first part in which oesophagus opens. The cardia surrounds the band of circular muscles present at the junction of oesophagus and stomach called cardiac sphincter. The cardiac sphincter prevents back flow or regurgitation of food from stomach to oesophagus.
2. Fundus: It is the dome shaped region above and left of cardia.
3. Body: It forms the large central portion of stomach that stores the food.
4. Pylorus: It is a narrow posterior region of stomach.
   It opens into duodenum, the initial part of small intestine.
   This opening is guarded by a set of sphincter muscles called pyloric sphincter.
   It regulates the flow of food from stomach to small intestine.

Function: The stomach temporarily stores the food.
It chums the food and helps in mixing the food with gastric juice.

Question 8.
Describe the structure of Small Intestine.
Answer:
It is about 6 meters long and 2.5 cm broad tube coiled within abdominal cavity.
The coils are held together by mesenteries, supporting the blood vessels, lymph vessels and nerves.
It is divided into three parts.

1. Duodenum:
   • It is about 26 cm long ‘U’ shaped structure.
   • The duodenum turns towards left side of abdominal cavity below the stomach.
2. Jejunum:
   • It is about 2.5 meters long, coiled middle portion of small intestine.
   • It is narrower than the duodenum.
3. Ileum:
   • It is about 3.5 meters long.
   • It is highly coiled and little broader than jejunum.
   • The ileum opens into the caecum of large intestine at ileocaecal junction.

Question 9.
Explain anatomy of different parts of Large Intestine.
Answer:
Ileum opens into large intestine.
It is 1.5 meters in length.
It is wider in diameter and shorter than small intestine.
It consists of caecum, colon and rectum.

1. Caecum:
   • Caecum is a small, blind sac present at the junction of ileum and colon.
   • It is 6cm in length.
   • It hosts some symbiotic microorganisms.
   • An elongated worm like vermiform appendix arises from the caecum.
   • Appendix is vestigial organ in human beings and functional in herbivorous animals for the digestion of cellulose.
2. Colon:
   • Caecum opens into colon.
   • Colon is tube like-organ consist of three parts, ascending colon, transverse colon and descending colon.
   • The colon is internally lined by mucosal cells.
3. Rectum:
   • It is posterior region of large intestine.
   • It temporarily stores the undigested waste material called faeces till it is egested out through anus.

Question 10.
Differentiate between Small Intestine and Large Intestine
Answer:

	Small Intestine	Large Intestine
i.	It is about 6 meters long.	It is about 1.5 meters long.
ii	Small intestine is 2.5 cm broad tube.	Large intestine is broader than the small intestine. !
iii.	It is divided into three parts, as Duodenum, Jejunum, Ileum.	It is divided into three parts as – caecum, colon I and rectum.
iv	Absorbs the digested nutrients.	Takes part in absorption of water and minerals.
V.	Villi present.	Villi absent.
vi.	Digestion is completed in small intestine.	No role in digestion.

Question 11.
Explain in detail the layers of gastrointestinal tract.
Answer:
The entire gastrointestinal tract is lined by four basic layers from inside to outside namely, mucosa, submucosa, muscularis and serosa.
These layers show modification depending on the location and function of the organ concerned.

1. Serosa:
   • It is the outermost layer.
   • It is made up of a layer of squamous epithelium called mesothelium and inner layer of connective tissue.
2. Muscularis:
   • This layer is formed of smooth muscles.
   • These muscles are usually arranged in three concentric layers.
   • Outermost layer shows longitudinal muscles, middle circular muscles and inner oblique muscles.
   • This layer is wider in stomach and comparatively thin in intestinal region.
   • The layer of oblique muscles is absent in the intestine.
3. Submucosa:
   • It is formed of loose connective tissue containing blood vessels, lymph vessels and nerves.
   • Duodenal submucosa shows presence of glands.
4. Mucosa:
   • The lumen of the alimentary canal is lined by mucosa.
   • Throughout the length of alimentary canal, the mucosa layer shows presence of goblet cells that secrete mucus.
   • This lubricates the lumen of alimentary canal.
   • This layer shows modification in different regions of alimentary canal. In stomach, it is thrown into irregular folds called rugae.
   • In stomach mucosa layer forms gastric glands that secrete gastric juice.

Question 12.
Write a short note on villi.
Answer:

1. Mucosa of small intestine forms finger like folding called villi.
2. The intestinal villi are lined by brush border or epithelial cells having microvilli at the free surface.
3. Villi are supplied with a network of capillaries and lymph vessels called lacteals.
4. Mucosa forms crypis in bctween the bases of vifli in intestine called crvpís of Licberkuhn which arc intestinal glands.

Question 13.
Describe the various digestive glands associated with alimentary canal.
Answer:
The digestive glands associated with the alimentary canal include the salivary glands, liver and pancreas.

1. Salivary Glands:
   • There are three pairs of salivary glands which open in buccal cavity.
   • Parotid glands are present in front of the ear.
   • The submandibular glands are present below the lower jaw.
   • The glands present below the tongue are called sublingual.
   • Salivary glands are made up of two types of cells.
   • Serous cells secrete a fluid containing digestive enzyme called salivary amylase.
   • Mucous cells produce mucus that lubricates food and helps swallowing.
2. Liver:
   • Liver is dark reddish-brown coloured largest gland of the body, weighing 1.2 to 1.5 kg, in adults.
   • Situated in right upper portion of the abdominal cavity, below the diaphragm.
   • Divided into 2 lobes, right and left.
   • A thin connective tissue sheath called Glisson’s capsule covers the liver and invaginates inside to divide the liver into cord like structures called hepatic lobules which are functional units of liver containing hepatic cells (hepatocytes).
   • Each hepatic lobule is polygonal in shape. At the junction of adjacent lobules, a triangular portal area is present.
   • In this portal area a branch of each of hepatic artery, hepatic portal vein and bile duct are present. Lobule consist of cords of hepatic cells which are arranged around a central vein.
   • In between the cords of hepatic cells, spaces called sinusoids are present through which the blood flows. In the sinusoids, phagocytic cells called Kupffer cells are present.
   • Hepatic cells secrete bile. Bile is carried by hepatic ducts in a thin muscular sac called gall bladder.
   • The duct of the gall bladder and hepatic duct together form common bile duct.
   • Liver synthesizes vitamins A, D, K and B₁₂, blood proteins.
3. Pancreas:
   • Pancreas is a leaf shaped heterocrine gland present in the gap formed by bend of duodenum under the stomach.
   • Exocrine part of pancreas is made up of acini, the acinar cells secrete alkaline pancreatic juice that contains various digestive enzymes.
   • Pancreatic juice is collected and carried to duodenum by pancreatic duct.
   • The common bile duct joins pancreatic duct to form hepato-pancreatic duct. It opens into duodenum.
   • Opening of hepato-pancreatic duct is guarded by sphincter of Oddi.
   • Endocrine part of pancreas is made up of islets of Langerhans situated between the acini.
   • It contains three types of cells a-cells which secrete glucagon, P-cells which secretes insulin and 5 cells secrete somatostatin hormone.
   • Glucagon and insulin together control the blood-sugar level.
   • Somatostatin hormone inhibits glucagon and insulin secretion.

Question 14.
Observe the diagram given below and explain the structure and functions of the gland which stores glycogen and is involved in detoxification.

Answer:
The gland which stores glycogen and helps in detoxification is liver.

1. Liver:
   • Liver is dark reddish-brown coloured largest gland of the body, weighing 1.2 to 1.5 kg, in adults.
   • Situated in right upper portion of the abdominal cavity, below the diaphragm.
   • Divided into 2 lobes, right and left.
   • A thin connective tissue sheath called Glisson’s capsule covers the liver and invaginates inside to divide the liver into cord like structures called hepatic lobules which are functional units of liver containing hepatic cells (hepatocytes).
   • Each hepatic lobule is polygonal in shape. At the junction of adjacent lobules, a triangular portal area is present.
   • In this portal area a branch of each of hepatic artery, hepatic portal vein and bile duct are present. Lobule consist of cords of hepatic cells which are arranged around a central vein.
   • In between the cords of hepatic cells, spaces called sinusoids are present through which the blood flows. In the sinusoids, phagocytic cells called Kupffer cells are present.
   • Hepatic cells secrete bile. Bile is carried by hepatic ducts in a thin muscular sac called gall bladder.
   • The duct of the gall bladder and hepatic duct together form common bile duct.
   • Liver synthesizes vitamins A, D, K and B₁₂, blood proteins.
2. Kupffer cells of liver destroy toxic substances, dead and worn-out blood cells and microorganisms.
3. Bile juice secreted by liver emulsifies fats and makes food alkaline.
4. Liver stores excess of glucose in the form of glycogen.
5. Deamination of excess amino acids to ammonia and its further conversion to urea takes place in liver.
6. Synthesis of vitamins A, D, K and B₁₂ takes place in liver.
7. It also produces blood proteins like prothrombin and fibrinogen.
8. During early development, it acts as haemopoietic organ.

Therefore, liver is a vital organ.

Question 15.
Explain heterocrine nature of pancreas with the help of histological structure.
Answer:
Pancreas:

1. Pancreas is a leaf shaped heterocrine gland present in the gap formed by bend of duodenum under the stomach.
2. Exocrine part of pancreas is made up of acini, the acinar cells secrete alkaline pancreatic juice that contains various digestive enzymes.
3. Pancreatic juice is collected and carried to duodenum by pancreatic duct.
4. The common bile duct joins pancreatic duct to form hepato-pancreatic duct. It opens into duodenum.
5. Opening of hepato-pancreatic duct is guarded by sphincter of Oddi.
6. Endocrine part of pancreas is made up of islets of Langerhans situated between the acini.
7. It contains three types of cells a-cells which secrete glucagon, P-cells which secretes insulin and 5 cells secrete somatostatin hormone.
8. Glucagon and insulin together control the blood-sugar level.
9. Somatostatin hormone inhibits glucagon and insulin secretion.
   

Question 16.
Digestion is carried out by both mechanical and chemical methods. Justify.
Answer:

1. Mechanical digestion includes various movements of alimentary canal that help chemical digestion.
2. Mastication or chewing of food by teeth, churning in stomach and peristaltic movements of gastrointestinal tract bring about mechanical digestion in human body.
3. Chemical digestion is a series of catabolic (breaking down) reactions that hydrolyze the food.
   Thus, Digestion is carried out by both mechanical and chemical methods.

Question 17.
Write a short note on digestion in the mouth.
Answer:
Digestion in the mouth (buccal cavity):

1. Both mechanical and chemical digestion processes take place in mouth.
2. Mastication or chewing of food takes place with the help of teeth and tongue.
3. Teeth crush and grind the food while tongue manipulates the food.
4. Crushing of food becomes easier when it gets moistened by saliva.
5. Mucus in the saliva lubricates the food as well as it helps in binding the food particles into a mass of called bolus which is swallowed by deglutition.
6. The tongue presses against the palate and pushes the bolus into pharynx which further passes oesophagus.
7. The only chemical digestion that takes place in mouth is by the action of salivary amylase.
8. It helps in conversion of starch into maltose. About 30% starch gets converted to maltose in mouth.
9. The bolus further passes down through oesophagus by peristalsis.
10. Food from the oesophagus enters the stomach.
    

Question 18.
Name all the constituents of saliva.
Answer:
Saliva contains 98% water and 2% other constituents like electrolytes (sodium, potassium, calcium, chloride, bicarbonates), digestive enzyme, salivary amylase and lysozyme.

Question 19.
Which sphincter controls the passage of food into stomach?
Answer:
The gastro-oesophageal sphincter controls the passage of food into the stomach.

Question 20.
Explain the process of digestion taking place in muscular-sac like ‘J’ shaped organ.
Answer:
The muscular-sac like ‘J’ shaped organ is stomach.

1. Both mechanical and chemical digestion takes place in stomach.
2. The stomach stores the food for 4-5 hours.
3. The physical digestion take place by churning of food which done by thick muscular wall of stomach.
4. Churning further breaks down the food particles and also helps in thorough mixing of gastric juice with food.
5. The mucosa layer of stomach has gastric gland which shows presence of three major types of cells namely, mucus cells, peptic or chief cells and parietal or oxyntic cells.
6. Mucus cells secrete mucus; peptic or chief cells secrete proenzyme pepsinogen and parietal cells secrete HCl and intrinsic factor which is essential for absorption of vitamin B12. Thus, gastric juice contains mucus, inactive enzyme pepsinogen, HCl and intrinsic factor.
7. Mucus protects the inner lining of stomach from HCl present in gastric juice.
8. HCl in gastric juice makes the food acidic and stops the action of salivary amylase, and also kills the germs
   that might be present in the food.
9. Pepsinogen gets converted into active enzyme pepsin in the acidic medium provided by HCl.
10. In presence of pepsin, proteins in the food get converted into simpler forms like peptones and proteoses.
11. At the end of gastric digestion, food is converted to a semifluid acidic mass of partially digested food is
    called chyme.
12. The chyme from stomach is pushed in the small intestine through pyloric sphincter for further digestion.
    

Question 21.
What is the role of rennin in infants?
Answer:

1. Rennin found in gastric juice of infants acts on casein, a protein present in milk.
2. It brings about curdling of milk proteins with the help of calcium.
3. The coagulated milk protein is further digested with the help of pepsin.
4. Rennin is absent in adults.

Question 22.
Describe the process of digestion in small intestine.
Answer:

1. In the small intestine, intestinal juice, bile juice and pancreatic juice are mixed with food. Peristaltic movements of muscularis layer help in proper mixing of digestive juices with chyme.
2. Bile juice and pancreatic juice are poured in duodenum through hepato-pancreatic duct.
3. Bile salts present in the bile juice neutralize the acidic chyme and make it alkaline. II brings about emulsification of fats.
4. Pancreatic juices are secreted by pancreas whereas the intestinal mucosa secretes digestive enzymes. The goblet cells produce mucus.
5. The intestinal juice contains various enzymes like dipeptidases, lipases, disaccharidases, maltase, sucrase and lactase.
6. Both pancreatic and intestinal lipases initially convert fats into fatty acid and diglycerides.
7. Diglycerides are further converted to monoglycerides by removal of fatty acid from glycerol.
8. The mucus and bicarbonates present in pancreatic juice protect the intestinal mucosa and provide alkaline medium for enzymatic action.
9. Sub-mucosal Brunner’s glands help in the action of goblet cells.
10. Most of the digestion gets over in small intestine.

Question 23.
Write a short note on bile.
Answer:

1. Bile juice is dark green coloured fluid that contains bile pigments (bilirubin and biliverdin), bile salts (Na- glycocholate and Na-taurocholate), cholesterol and phospholipid.
2. Bile does not contain any digestive enzyme.
3. Bile salts neutralise the acidity of chyme and make it alkaline.
4. It brings about emulsification of fats.
5. It also activates lipid digesting enzymes or lipases.
6. Bile pigments impart colour to faecal matter.

Question 24.
What are the constituents of pancreatic juice?
Answer:

• Pancreatic juice secreted by pancreas contains pancreatic amylases, lipases and inactive enzymes trypsinogen and chymotrypsinogen.
• Pancreatic juice also contains nucleases- the enzymes that digest nucleic acids.

Question 25.
List the constituents of intestinal juice.
Answer:
The intestinal juice contains various enzymes like dipeptidases, lipases, disaccharidases, maltase, sucrase and lactase.

Question 26.
Fill in the blanks:
i. The ________ of mucosa produce mucus.
ii. Mucus plus intestinal enzymes together constitute intestinal juice or ________.
iii. Bile juice and pancreatic juice are poured in duodenum through _________ duct.
Answer:
i. goblet cells.
ii. Succus entericus.
iii. hepato-pancreatic.

Question 27.
Give the significance of peristaltic movement of muscularis in small intestine.
Answer:
Peristaltic movements of muscularis layer help in proper mixing of digestive juices with chyme.

Question 28.
Name the juices which are mixed with food in small intestines.
Answer:
Intestinal juice, bile juice and pancreatic juice.

Question 29.
Write a note on hunger hormone.
Answer:
i. Hunger hormone is also called Ghrelin.
ii. It is hormone that is produced mainly by the stomach and small intestine, pancreas and brain.
iii. It stimulates appetite, increases food intake and promotes fat storage.

Question 30.
Explain in detail the action of pancreatic juice.
Answer:

Question 31.
Explain the role of large intestine in digestion process.
Answer:

1. Conversion of proteins into amino acids, fats to fatty acids and monoglycerides, nucleic acids to sugar and nitrogenous base and carbohydrates to monosaccharides marks the end of digestion of food.
2. Food is now called chyle. Chyle is an alkaline slurry which contains various nutrients ready for absorption.
3. The nutrients are absorbed and undigested remains are transported to large intestine.
4. Mucosa of large intestine produces mucus but no enzymes.
5. Some carbohydrates and proteins do enter the large intestine.
6. These are digested by the action of bacteria that live in the large intestine.
7. Carbohydrates are fermented by bacterial action and hydrogen, carbon dioxide and methane gas are produced in colon.
8. Protein digestion in large intestine ends up into production of substances like indole, skatole and H2S.
9. These are the reason for the odour of faeces. These bacteria synthesize several vitamins like B vitamins and vitamin K.

Question 32.
What causes pancreatitis?
Answer:

1. Pancreatitis is inflammation of the pancreas.
2. It may occur due to alcoholism and chronic gallstones.
3. Other reasons include high levels of calcium, fats in blood.
4. However, in 70% of people with pancreatitis, main reason is alcoholism.

Question 33.
Match the following:

	Column I	Column II
i.	Cardiac Sphincter Pyloric	a. Regulates the flow of food from stomach to small intestine.
ii.	sphincter	b. Controls the passage of food from oesophagus into the stomach.
iii.	Gastro-oesophageal sphincter	c. Prevents back flow of food from stomach to oesophagus.

Answer:
(i – c)
(ii – a)
(iii – b)

Question 34.
Identify ‘X’, ‘Y’ and ‘Z’ in the given diarani and explain the regulation of gastric function.

Answer:

1. ‘X’- Vagus nerve, ‘Y’- Gastrin ‘Z’- Sympathetic nerve
2. Intestinal mucosa produces hormones like secretin, cholecystokinin (CCK) and gastric inhibiting peptide (G1P).
3. Secretin inhibits secretion of gastric juice.
4. It stimulates secretion of bile juice from liver, pancreatic juice and intestinal juice.
5. CCK brings about similar action and induces satiety that is feeling of fullness or satisfaction.
6. GIP also inhibits gastric secretion.

Question 35.
What is absorption? Mention the absorption of nutrients and other substances in alimentary canal?
Answer:
The passage of end products of digestion through the mucosal lining of alimentary canal into blood and lymph is called absorption. 90% of absorption takes place in small intestine and the rest in mouth, stomach and large intestine.

1. Month: Absorption takes place through mucosa of mouth and lower side of tongue into the blood capillaries, e.g. Some drugs like certain painkillers.
2. Stomach: Gastric mucosa is impermeable to most substances hence nutrients reach unabsorbed till small intestine. Little water, electrolytes, alcohol and drugs like aspirin get absorbed in stomach.
3. Small Intestine: Glucose, fructose, galactose, amino acids, minerals and water-soluble vitamins are absorbed in blood capillaries in villi. Lipids and fat-soluble vitamins ( A, D, E, K) are absorbed in lacteals.
4. Large Intestine: Absorption of water, electrolytes like sodium and chloride, drugs and some vitamins take place.

Question 36.
Name the various ways by which absorption takes place.
Ans
Simple diffusion, osmosis, facilitated transport and active transport.

Question 37.
Write the various mechanisms of absorption of compounds.
Answer:

1. Absorption of part of glucose, amino acids and some electrolytes like chloride ions are absorbed by simple diffusion depending on concentration gradient.
2. Some amino acids as well as substances like fructose are absorbed by facilitated transport.
3. In this method, carrier ions like Na+ bring about absorption.
4. Some ions are absorbed against concentration gradient. It requires energy. This type of absorption of mineral like sodium is called active transport.
5. Water is absorbed along the concentration gradient.
   [Note: Glucose and galactose are transported into absorptive cells of the villi through secondary active transport that is coupled to the active transport ofNa . Amino acids are transported via active transport.]

Question 38.
Write the transportation mechanism for monoglycerides and fatty acids.
Answer:

1. Monoglycerides and fatty acids cannot be absorbed in blood.
2. These dissolve in the centre of spherical aggregates fonned by bile salts called micelles.
3. Micelles enter into intestinal villi where they are reformed into chylomicrons.
4. Chylomicrons are small protein coated fat globules.
5. They are transported into lymph vessels called lacteals.
6. From here, they are transported to blood stream.

Question 39.
Observe the chart given on textbook page no. 169 to find out absorption in various parts of alimentary canal.
Answer:
The passage of end products of digestion through the mucosal lining of alimentary canal into blood and lymph is called absorption. 90% of absorption takes place in small intestine and the rest in mouth, stomach and large intestine.

1. Month: Absorption takes place through mucosa of mouth and lower side of tongue into the blood capillaries, e.g. Some drugs like certain painkillers.
2. Stomach: Gastric mucosa is impermeable to most substances hence nutrients reach unabsorbed till small intestine. Little water, electrolytes, alcohol and drugs like aspirin get absorbed in stomach.
3. Small Intestine: Glucose, fructose, galactose, amino acids, minerals and water-soluble vitamins are absorbed in blood capillaries in villi. Lipids and fat-soluble vitamins ( A, D, E, K) are absorbed in lacteals.
4. Large Intestine: Absorption of water, electrolytes like sodium and chloride, drugs and some vitamins take place.

Question 40.
What is assimilation?
Answer:
The absorbed food material finally reaches the tissue and becomes a part of protoplasm. This is called as assimilation.

Question 41.
Write a short note on egestion?
Answer:

1. Undigested waste is converted to faeces in colon and reaches rectum.
2. Faeces contain water, inorganic salts, sloughed of mucosal cells, bacteria and undigested food.
3. Distension of rectum stimulates pressure sensitive receptors that initiate a neural reflex for defecation or egestion.
4. It is a voluntary process that takes place through anal opening guarded by sphincter muscles.

Question 42.
How are nutrition related disorders categorised?
Answer:

• Little extra or less of nutrition can lead to dietary’ disorder (nutrition related disorder).
• Nutrition related disorders can be categorized based on the food that an individual consumes and conditions that develop due to malfunctioning of the organ/s or glands associated with digestive system.

Question 43.
What is PEM?
Answer:
Protein Energy malnutrition (PEM):

• Protein Energy Malnutrition is caused due to inadequate intake of proteins.
• It can be associated with inadequacy of vitamins and minerals in diet.
• PEM causes disease like Kwashiorkor and Marasmus.

Question 44.
What is Marasmus? What are the symptoms and causes?
Answer:

1. Marasmus is a prolonged protein energy malnutrition (PEM) found in infants under one year of age.
2. In this disease, protein deficiency is coupled with lower total food calorific value.
3. Inadequate diet impairs physical growth and retards mental development, subcutaneous fat disappears, ribs become prominent, limbs become thin, skin becomes dry, thin and wrinkled, loss of weight, digestion and absorption of food stops due to atrophy of digestive glands. There is no oedema.

Question 45.
What are the major causes of disorders like Kwashiorkor and Marasmus?
Answer:
Major causes of disorders like Kwashiorkor and Marasmus are unavailability of nutritious food. Poverty, large family size, ill spacing of children, early termination of breast feeding and overdiluted milk arc a few causes.

Question 46.
Write a short note on:
i. Indigestion
ii. Constipation
iii. Vomiting
Answer:

1. Indigestion:
   • Overeating, inadequate enzyme secretion, spicy food, anxiety can cause discomfort and various symptoms. It is called indigestion.
   • Improperly digested food or food poisoning also can cause indigestion.
   • It leads to loss of appetite, acidity (acid reflux), heart burn, regurgitation, dyspepsia (upper abdominal pain), stomach pain.
   • Avoiding eating large meal, lying down after meal, spicy, oily, junk food, smoking, alcohol are the.preventive measures for indigestion.
2. Constipation:
   • When frequency of defaecation is reduced to less than once per week the condition is called constipation.
   • Difficulty in defaecation may result in abdominal pain distortion, rarely perforation.
   • The causes are, affected colonic mobility due to neurological dysfunction like spinal cord injury, low fibre diet, inadequate fluid intake and inactivity.
   • Roughage, sufficient fluids in diet, exercise can help improve the conditions.
3. Vomiting
   • In this condition, the stomach contents are thrown out of the mouth due to reverse peristaltic movements of gastric wall.
   • It is controlled by non-vital vomiting center of medulla.
   • It is typically associated with nauseatic feeling.

Question 47.
What is diarrhoea? What are the symptoms and causes of diarrhoea?
Answer:

• Passing loose watery stools more than three times a day is called diarrhoea. Diarrhoea can lead to dehydration.
• The symptoms of diarrhoea are blood in stool, nausea, bloating, fever depending on cause and severity of the disorder.
• The causes of diarrhoea are infection through food and water or disorders like ulcer, colitis, inflammation of intestine or irritable bowel syndrome.

Question 48.
Distinguish between Kwashiorkor and Marasnius.
Answer:

	Kwashiorkor	Marasnius
i.	It is caused due to insufficient amount of proteins.	It is caused due to deficiency of fats, proteins and carbohydrates.
ii.	Oedema, fatty liver, lethargy are symptoms.	No oedema is observed. Thinning of limb is observed.
iii.	It is observed in children between 1 to 3 years of age.	It is observed in infants under one year of age.

Apply Your Knowledge

Question 49.
A person visited a pediatrician with his one-year old child complaining about the child’s weight loss and diarrhoea. The doctor examines the child and finds that his limbs have become thin, the skin has become dry as well as thin and wrinkled but there is no oedema on the body.
From this information answer the following questions:
i. Which disease child is suffering from?
ii. What is the probable reason for the disease?
iii. What would be the remedies and diet suggested by the doctor?
Answer:

1. The child is suffering from Marasmus.
2. The probable reason for the disease is Prolonged Protein Energy Malnutrition (PEM). This may cause if mother’s milk is replaced too early with foods having low protein content and calorific value.
3. Diet with adequate proteins and proper calorific value should be given to the infants.

Question 50.
Ramesh had dinner at his favorite Chinese restaurant. His menu included salad, large plate of paneer tikka masala, tandoori roti and red wine. For dessert, he consumed dark chocolate ice-cream and a glass of milkshake. He returned home and while lying on his couch watching TV he experienced chest pain and vomiting. Ramesh was taken to hospital and he was advised to watch his diet. What was the reason for Ramesh’s illness?
Answer:
Ramesh experienced reverse spasmodic peristalsis. The contents of the stomach backed up (refluxed) into Ramesh’s oesophagus. The HCL from the stomach irritated the walls of the oesophagus that resulted in burning sensation which is commonly known as heartburn. Ramesh’s heavy meal worsened the problem. Additionally, lying down immediately after meal intensified the problem.

Multiple Choice Questions

Question 1.
The roof of buccal cavity is called
(A) lingua
(B) tongue
(C) palate
(D) maxilla
Answer:
(C) palate

Question 2.
How many canine teeth are there in a normal human adult?
(A) 2
(B) 3
(C) 4
(D) 1 or 2
Answer:
(C) 4

Question 3.
What is the human dental formula?
(A) I 2/2, C 1/1, PM 2/2, M 3/3
(B) I 3/3, C2/2, PM 1/1, M 3/3
(C) I 1/1, C 3/3, PM 2/2, M 1/1
(D) T 2/2, C 2/2,PM 2/2, M 3/3
Answer:
(A) I 2/2, C 1/1, PM 2/2, M 3/3

Question 4.
The common passage of air and food is called
(A) pharynx
(B) larynx
(C) oesophagus
(D) trachea
Answer:
(A) pharynx

Question 5.
The long, thin and narrow tube connecting pharynx to the stomach is called
(A) Stomach
(B) Alimentary canal
(C) Oesophagus
(D) Duodenum
Answer:
(C) Oesophagus

Question 6.
The length of small intestine is________ metres.
(A) 15
(B) 6
(C) 2
(D) more than 30
Answer:
(B) 6

Question 7.
Main function of rectum is
(A) absorption of water from the undigested matter
(B) digestion and absorption of fats
(C) temporary storage of undigested matters
(D) both(A) and (C)
Answer:
(C) temporary storage of undigested matters

Question 8.
Vestigial organ of human body is
(A) caecum
(B) ileum
(C) appendix
(D) rectum
Answer:
(C) appendix

Question 9.
Find the odd one out.
(A) Parotid
(B) Sub – lingual
(C) Sub – maxillary
(D) Acinar
Answer:
(D) Acinar

Question 10.
The name of salivary glands present in front of ear is
(A) parotid
(B) sub maxillary
(C) sub lingual
(D) parietal
Answer:
(A) parotid

Question 11.
The largest gland of the human body is
(A) pancreas
(B) liver
(C) salivary glands
(D) thyroid
Answer:
(B) liver

Question 12.
Emulsification of fats is done by
(A) saliva
(B) gastric juice
(C) bile
(D) intestinal juice
Answer:
(C) bile

Question 13.
Kupffer cells are found in
(A) Liver
(B) Pancreas
(C) Buccal cavity
(D) Pharynx
Answer:
(A) Liver

Question 14.
The _____ cells present in pancreas secrete somatostatin hormone.
(A) Alpha
(B) Beta
(C) Delta
(D) Omega
Answer:
(C) Delta

Question 15.
Salivary amylase brings about the digestion of
(A) proteins
(B) fats
(C) carbohydrates
(D) vitamins
Answer:
(C) carbohydrates

Question 16.
Which component of saliva acts as an antibacterial agent?
(A) Lysozyme
(B) electrolytes
(C) salivary amylase
(D) water
Answer:
(A) Lysozyme

Question 17.
The enzyme in saliva that digests starch is
(A) pepsin
(B) amylase
(C) rennin
(D) maltase
Answer:
(B) amylase

Question 18.
Gastric juice contains
(A) H₂SO₄
(B) HCl
(C) ptyalin
(D) bile
Answer:
(B) HCl

Question 19.
_______ stops the activity of salivary amylase.
(A)H₂SO₄
(B) HCl
(C) Pepsin
(D) Protease
Answer:
(B) HCl

Question 20.
Proteins are broken down into Peptones by the action of
(A) Pepsin
(B) Proteases
(C) Trypsin
(D) Peptidase
Answer:
(A) Pepsin

Question 21.
Digestion in the small intestine occurs in
(A) acidic medium
(B) alkaline medium
(C) neutral medium
(D) isotonic solution
Answer:
(B) alkaline medium

Question 22.
Acidic medium of chyme is made alkaline by
(A) succus entericus
(B) pancreatic juice
(C) bile
(D) all of these
Answer:
(C) bile

Question 23.
Succus entericus is the name given to
(A) a junction between ileum and large intestine
(B) intestinal juice
(C) swelling in the gut
(D) appendix
Answer:
(B) intestinal juice

Question 24.
Protein deficiency in children causes
(A) kwashiorkor
(B) gigantism
(C) dwarfism
(D) jaundice
Answer:
(A) kwashiorkor

Question 25.
Protruding belly is a characteristic symptom of
(A) Marasmus
(B) Diarrhoea
(C) Jaundice
(D) Kwashiorkor
Answer:
(D) Kwashiorkor

Question 26.
PEM can cause disease like
(A) Marasmus
(B) jaundice
(C) diarrhea
(D) constipation
Answer:
(A) Marasmus

Question 27.
Among the following, which is a symptom of constipation?
(A) Loose motion
(B) Difficulty in defecation
(C) Vomiting
(D) Yellowing of eyes
Answer:
(B) Difficulty in defecation

Question 28.
Jaundice is caused due to
(A) abnormal bilirubin metabolism
(B) abnormal carbohydrate metabolism
(C) abnormal lipid metabolism
(D) abnormal protein metabolism
Answer:
(A) abnormal bilirubin metabolism

Question 29.
Vomiting is caused due to
(A) peristalsis
(B) reverse epistasis
(C) reverse spasmodic peristalsis
(D) osmosis
Answer:
(C) reverse spasmodic peristalsis

Competitive Corner

Question 1.
Match the items given in column-I with those in column-II and choose the correct option: [NEET Odisha 2019]

	Column I	Column II
i.	Rennin	a. Vitamin B12
ii.	Enterokinase	b. Facilitated transport
iii.	Oxyntic cells	c. Milk proteins
iv.	Fructose	d. Trypsinogen

(A) i – c, ii – d, iii – a, iv – b
(B) i – c, ii – d, iii – b, iv – a
(C) i – d, ii – c, iii – a, iv – b
(D) i – d, ii – c, iii – b, iv – a
Hint: Rennin is an enzyme which digests milk proteins. Enterokinase enzyme helps in conversion of trypsinogen into trypsin. Fructose is transported through facilitated transport. Oxyntic cells secrete Hydrochloric acid and intrinsic factors that play significant role in absorption of vitamin B₁₂.
Answer:
(A) i – c, ii – d, iii – a, iv – b

Question 2.
Kwashiorkor disease is due to – [NEET Odisha 2019]
(A) protein deficiency not accompanied by calorie deficiency
(B) simultaneous deficiency of proteins and fats
(C) simultaneous deficiency of proteins and calories
(D) deficiency of carbohydrates
Answer:
(A) protein deficiency not accompanied by calorie deficiency

Question 3.
Match the following structures with their respective location in orgAnswer: [NEET (UG) 2019]

i.	Crypts of Lieberkuhn	P	Pancreas
ii.	Glisson’s Capsule	q.	Duodenum
iii.	Islets of Langerhans	r.	Small intestine
iv.	Brunner’s Glands	s.	Liver

Select the correct option from the following:
(A) i – r, ii – s, iii – p, iv – q
(B) i – r, ii – q, iii – p, iv – s
(C) i – r, ii – p, iii – q, iv – s
(D) i – q, ii – s, iii – p, iv – r
Answer:
(A) i – r, ii – s, iii – p, iv – q

Question 4.
Identify the cells whose secretion protects the lining of gastro – intestinal tract from various enzymes. [NEET (UG) 2019]
(A) Oxyntic cells
(B) Duodenal cells
(C) Chief cells
(D) Goblet cells
Answer:
(D) Goblet cells

Question 5.
Which of the following terms describe human dentition? [NEET (UG) 2018]
(A) Pleurodont, monophyodont, homodont
(B) Thecodont, diphyodont, heterodont
(C) Thecodont, diphyodont, homodont
(D) Pleurodont, diphyodont, heterodont
Answer:
(B) Thecodont, diphyodont, heterodont

Question 6.
Lacteals absorb _________ [MHT CET 2018]
(A) amino acids
(B) fatty acids and glycerol
(C) glucose and fructose
(D) amylose and maltose
Answer:
(B) fatty acids and glycerol

Question 7.
Following are various symptoms of marasmus except, [MHT CET 2018]
(A) oedema of lower legs and face
(B) dry, wrinkled skin
(C) extreme leanness
(D) atrophy of digestive glands
Answer:
(A) oedema of lower legs and face

Question 8.
One of the following groups of enzymes forms contents of succus entericus [MHT CET 2018]
(A) maltase, enterokinase, trypsin
(B) trypsin, pepsin, lactase
(C) nuclease, amylase, chymotrypsin
(D) sucrase, maltase, dipeptidase
Answer:
(D) sucrase, maltase, dipeptidase

Question 9.
A baby boy aged two years is admitted to play school and passes through a dental check-up. The dentist observed that the boy had twenty teeth. Which teeth were absent? [NEET (UG) 2017]
(A) Incisors
(B) Canines
(C) Pre-molars
(D) Molars
Answer:
(C) Pre-molars

Question 10.
Which of the following options best represents the enzyme composition of pancreatic juice? [NEET (UG) 2017]
(A) amylase, peptidase, trypsinogen, rennin
(B) amylase, pepsin, trypsinogen, maltase
(C) peptidase, amylase, pepsin, rennin
(D) lipase, amylase, trypsinogen, procarboxypeptidase
Answer:
(D) lipase, amylase, trypsinogen, procarboxypeptidase