NCERT Class 11-Biology: Chapter –16 Digestion and Absorption Part 4

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Question 5:

Correct the statement given below by the right option shown in the bracket against them

a. Absorption of amino acids and glycerol takes place in the. (Small intestine/ large intestine)

b. The faeces in the rectum initiate a reflex causing an urge for its removal. (Neural /hormonal)

c. Skin and eyes turn yellow in infection. (Liver /stomach)

d. Rennin is a proteolytic enzyme found in gastric juice in (infants / adults).

e. Pancreatic juice and bile are released through. (Intestine pancreatic/ hepato- pancreatic duct)

f. Dipeptides, disaccharides and glycerides are broken down into simple substances in region of small intestine. (Jejunum/ duodenum)

Answer:

a. Absorption of amino acids and glycerol takes place in the small intestine.

b. The faeces in the rectum initiate a neural reflex causing an urge for its removal.

c. Skin and eyes turns yellow in liver infection.

d. Rennin is a proteolytic enzyme found in gastric juice in infants.

e. Pancreatic juice and bile are released through hepato- pancreatic duct.

f. Dipeptides, disaccharides and glycerides are broken down into simple substances in region of small intestine called jejunum.

Question 6:

What are three major types of cells found in the gastric glands? Name their secretions.

Answer:

The three major types of cells found in the gastric glands with their secretions are as follows:

i. Mucous Neck cells – they secrete mucus

ii. Peptic or chief cells – they secrete Proenzyme Pepsinogen and Prorennin

iii. Parietal or oxyntic cells – they secrete and intrinsic factor. Intrinsic factor is essential for absorption of vitamin.

Question 7:

How is the intestinal mucosa protected from the acidic food entering from stomach?

Answer:

The intestinal mucosal epithelium has goblet cells which secrete mucus.

The secretion of brush border cells (of mucosa) and the goblet cells together form intestinal juice also known as success enteric us. This juice contains enzymes like disaccharides, Dipeptidases, lipases, Nucleosidases, etc.

The mucus plus the bicarbonates from the pancreas protects the intestinal mucosa from acidic food entering from the stomach. They also provide an alkaline medium (pH 7.8) for enzymatic activities.

Question 8:

How are the activities of gastro-intestinal tract regulated?

Answer: The activities of gastro-intestinal tract (GI tract) are regulated by neural system and hormonal system.

The activities of GI tract are usually under neural and hormonal control for proper coordination.

The GI tract is connected by many intrinsic and extrinsic nerves. These nerves help in proper functioning of different parts of alimentary canal and many hormones also helps in this.

Question 9:

Distinguish between constipation and indigestion. Mention their major causes.

Answer:

Distinguish between Constipation and Indigestion
Distinguish between constipation and indigestion

Constipation

Indigestion

The faeces are retained within the rectum.

The food is not digested properly leading to a feeling of fullness.

The bowel movement occurs irregularly

Causes: Less intake of water, less intake of roughage in the diet

Causes: Inadequate enzyme secretion, anxiety food poisoning, over eating, and spicy food

Remedy: drink more water, take more roughage in the diet, and exercise regularly.

Remedy: Take medications

Question 10:

Describe the enzymatic action on fats in the duodenum.

Answer:

The enzymatic action on fats in the duodenum is as follows:

The bile carries out the emulsification of fat.

Then fat is broken down by the enzyme lipase into Diglycerides and monoglycerides.

Next intestinal lipases act on these Diglycerides and monoglycerides and form fatty acids and glycerol.

The above steps are written in reactions as follows:

FatsDiglycerides Monoglycerides

Diglycerides and Monoglycerides Fatty acids Glycerol

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