NCERT Class 7 Science Second Chapter Nutrition In Animals Exercise Solutions

Exercises

(1) Fill in the blanks:

(a) The main steps of nutrition in humans are ingestion, digestion, assimilation and egestion.

(b) The largest gland in the human body is liver.

(c) The stomach releases hydrochloric acid and digestive juices which act on food.

(d) The inner wall of the small intestine has many finger-like outgrowths called villi.

(e) Amoeba digests its food in the food vacuole.

(2) Mark ‘T’ if the statement is true and ‘F’ if it is false:

(a) Digestion of starch starts in the stomach. = False

(b) The tongue helps in mixing food with saliva. = True

(c) The gall bladder temporarily stores bile= True

(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. = True

(3) Tick (√) mark the correct answer in each of the following:

(a) Fat is completely digested in the

Ans: (iii) small intestine

(b) Water from the undigested food is absorbed mainly in the

Ans: (iv) large intestine

(4) Match the items of Column I with those given in

(5) What are villi? What is their location and function?

Ans: The inner walls of the small intestine have thousands of finger-like outgrowths. These are called villi.

The villi increase the surface area for absorption of the digested food.

(6) Where is the bile produced? Which component of the food does it help to digest?

Ans: Liver secretes bile juice that is stored in a sac called the gall bladder (Fig. 2.2).

The bile plays an important role in the digestion of fats.

(7) Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.

Ans: The cellulose, a type of carbohydrate. Caecum between the oesophagus and the small intestine. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans.

(8) Why do we get instant energy from glucose?

Ans: In the cells, glucose breaks down with the help of oxygen into carbon dioxide and water, and energy is released. The food that remains undigested and unabsorbed enters into the large intestine.

(9) Which part of the digestive canal is involved in:

(i) Absorption of food small intestine.

(ii) Chewing of food buccal cavity.

(iii) Killing of bacteria stomach.

(iv) Complete digestion of food small intestine.

(v) Formation of faeces large intestine.

(10) Write one similarity and one difference between the nutrition in amoeba and human beings.

Ans: Similarity: Amoeba and human both have holozoic type of nutrition.

Difference:

(11) Match the items of Column I with suitable items in Column II

(12) Label Fig. 2.11 of the digestive system.

(13) Can we survive only on raw, leafy vegetables/grass? Discuss.

Ans: No human not survive only on raw, leafy vegetables. The grass is rich in cellulose, a type of carbohydrate. In ruminants like cattle, deer, etc., bacteria present in rumen helps in digestion of cellulose. Many animals, including humans, cannot digest cellulose.

INSIDE QUESTIONS

(1) What is called digesion?

Ans:- The breakdown of complex components of food into simpler substances is called digesion.

(2) What is called ingestion?

Ans:- The process of taking food into the body is called ingestion.

(3) What is tooth decay?

Ans:- If we do not clean our teeth and mouth after eating many harmful bacteria begin to live and grow in it. These bacteria

breakdown the sugars present from the leftover food and release acids. The acid gradually damaged the teeth. This is called

tooth decay.

(4) Define absorption?

Ans:- The digested food Pass into the blood vessel in the wall of the intestine. This Process is called absorption.

(5) What is the length of large intestine?

Ans:- 1.5 meter

(6) What is egestion?

Ans:- The facial matter is removed through the anus from time to time this is called egestion.

(7) What is the length of small intestine?

Ans:- 7.5 meter.

(8) What is diarrhoea?

Ans:- Need to pass watery stool frequently. This condition is known as diarrhea.

(9) What is oral Rehydration solution (ORS)?

Define rumination

Ans:- The cud returns to the mouth in small lumps and animal chews it. This Process is called rumination.