NCERT Solutions for Class 7 Science Chapter 2

Nutrition in Animals

NCERT Solutions for Class 7 Science Chapter 2 Exercise Question

Question1.

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 ____________ .

Answer 1:

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 thefood vacuole.

Question 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)

Answer 2

Question 3.

Tick (✓) mark 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

Answer

iii)Small intestine.
(b) Water from the undigested food is absorbed mainly in the
(i) stomach (ii) foodpipe (iii) small intestine (iv) large intestine

Answer

iii)Large intestine.

Question 4.

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

Answer 4

Question 5.

What are villi? What is their location and function?

Answer 5

The finger-like outgrowths on the inner surface of the small intestine which help in absorbing the digested food are called vill The villi increase the surface area for absorption of the digested food. Each villus has a network of thin and small blood vessels close to its surface. The surface of the villi absorbs the digested food materials.

Question 6.

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

Answer 6

liver produced bile juice that is stored in a sac called the gall bladder . It plays an important role in the digestion of fats.

Question 7.

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

Answer 7

The name of the carbohydrate is cellulose. It is digested by ruminants but not by humans because ruminants have a large sac-like structure called rumen which is located between the small intestine and large intestine. Certain enzymes present which digest cellulose and that is not present in humans.

Question 8.

Why do we get instant energy from glucose?

Answer 8

Glucose is the simplest form of carbohydrates and in the cell glucose break down with the help of oxygen into carbon dioxide and water and lots of energy is released and we get instant energy

Question 9.

Which part of the digestive canal is involved in
(i) absorption of food ________________.
(ii) chewing of food ________________.
(iii) killing of bacteria ________________.
(iv) complete digestion of food ________________
(v) formation of faeces ________________.

Answer 9

Absorption of food small intestine.
Chewing of food buccal cavity
Killing of bacteria _ stomach
Complete digestion of food small intestine
Formation of faeces large intestine

Question 10.

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

Answer 10

Similarity: Both Amoeba and human beings are heterotrophs and derive nutrition from other organisms andboth need digestive juices for the digestion of food.
Dissimilarity: Human beings have a complex digestive system and different nutrients are digested in separate regions. Amoeba does not have a digestive system and all the nutrients are digested in the food vacuole and also Humans need to chew the food on the other hand amoeba does not need to chew the food.

Question 11.

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

Answer 11

Question 12.

Label Fig. 2.11 of the digestive system

Answer 12

Question 13.

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

Answer 13

No, It is because the grass is rich in cellulose, which is a type of carbohydrate that humans are not able to digest due to the absence of cellulose-digesting enzymes We need all required nutrients, such as carbohydrates, proteins, lipids, vitamins and minerals, from them .So,We cannot survive only on raw, leafy vegetables/grass, because we need balance diet to live long and healthy life.