NCERT Solutions for Class 7 Science Chapter 2

NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals

Exercise Questions

1. Fill in the blanks:

(a) The main steps of nutrition in humans are _________, __________, __________, _________ and __________.

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

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

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

(e) Amoeba digests its food in the ____________ .

Solution:

(a) The main steps of nutrition in humans are ingestion, digestion, absorption, 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. (T/F)

(b) The tongue helps in mixing food with saliva. (T/F)

(c) The gall bladder temporarily stores bile. (T/F)

(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/F)

Solution:

a) F

b) T

c) T

d) T

3. Choose the correct answer in each of the following:

(a) Fat is completely digested in the

(i) stomach

(ii) mouth

(iii) small intestine

(iv) large intestine

Ans: (iii) small intestine

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

(i) stomach

(ii) foodpipe

(iii) small intestine

(iv) large intestine

Ans: (iv) large intestine

4. Match the items of Column I with those given in Column II:

Column- IColumn- II
Food componentsProduct(s) of digestion
CarbohydratesFatty acids and glycerol
ProteinsSugar
FatsAmino acids

Solution:

Column- IColumn- II
Food componentsProduct(s) of digestion
CarbohydratesSugar
ProteinsAmino acids
FatsFatty acids and glycerol

5. What are villi? What is its location and function?

Solution

Villi are the finger-like projections present on the surface of small intestine.

They are present in the small intestine of our digestive system. 

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?

Solution:

Bile juice is produced in the liver, and it helps in the digestion of fats by breaking large fat globule into smaller ones.

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

Solution:

Cellulose is the carbohydrate that can be digested by ruminants but not by humans because humans lack cellulose enzyme required to digest the cellulose.

8. Why do we get instant energy from glucose?

Solution:

Glucose is a simple sugar which is easily absorbed by the blood whereas other carbohydrates are first broken down into glucose and then absorbed; hence, glucose gives instant energy.

9. Which part of the digestive canal is involved in:

(i) absorption of food ________________.

Ans: i) Small intestine

(ii) chewing of food ________________.

Ans: ii) Buccal cavity

(iii) killing of bacteria ________________.

Ans: iii)Stomach

(iv) complete digestion of food ________________.

Ans: iv) Small intestine

(v) formation of faeces ________________.

Ans: v) Large Intestine

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

Solution:

Similarity: Both amoeba and human beings follow the holozoic type of nutrition.

Difference:

Humans intake food through buccal cavity. In amoeba, food is ingested through pseudopodia.

11. Match the items of Column I with suitable items in Column II

Column-IColumn-II
a) Salivary gland(i) Bile juice secretion
b) Stomach(ii) Storage of undigested food
c) Liver(iii) Saliva secretion
d) Rectum(iv) Acid release
e) Small intestine(v) Digestion is completed
f) Large intestine(vi) Absorption of water
(vii) Release of faeces

Solution:

Column-IColumn-II
a) Salivary gland(iii) Saliva secretion
b) Stomach(iv) Acid release
c) Liver(i) Bile juice secretion
d) Rectum(ii) Storage of undigested food
e) Small intestine(v) Digestion is completed
f) Large intestine(vi) Absorption of water

12. Label Fig. 2.11 of the digestive system.

Human digestive system

Solution:

Human digestive system

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

Solution:

No, we cannot survive only on raw, leafy vegetables because they mainly consist of Cellulose which cannot be digested by us due to lack of cellulose digesting enzyme in our body.

see also: Nutrition and mode of nutrition

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