Nutrition in Animals
Science Class Seven
NCERT Solution
Question (1) Fill in the blanks:
(a) The main steps of nutrition in humans are ______, _______, _______, _______, and ______.
Answer : The main steps of nutrition in humans are Ingestion, digestion, Absorption, Assimilation, andEgestion.
(b) The largest gland in the human body is _______.
Answer The largest gland in the human body is Liver.
(c) The stomach releases hydrochloric acid and ________ juices which act on food.
Answer : 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 _______.
Answer : The inner wall of the small intestine has many finger-like outgrowths called villi.
(e) Amoeba digest its food in the ______.
Answer : Amoeba digest its food in the food vacuoles.
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)
Answer : F
Explanation : Salivary glands present in mouth secretes saliva, which is a type of amylase. Saliva breaks down the starch into sugar. Thus digestion of starch starts in the stomach.
Hence, given sentence is false (F).
(b) The tongue helps in mixing food with saliva. (T/F)
Answer: T
(c) The gall bladder temporarily stores bile. (T/F)
Answer : T
(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/F)
Answer : T
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 : (iv) Large intestine
Question (4) Match the items of Column I with those given in Column II
| Column I | Column II |
|---|---|
| Food components | Product(s) of digestion |
| Carbohydrates | Fatty acids and glycerol |
| Proteins | Sugar |
| Fats | Amino acids |
Answer
| Column I | Column II |
|---|---|
| Food components | Product(s) of digestion |
| Carbohydrates | Sugar |
| Proteins | Amino Acids |
| Fats | Fatty acids and glycerol |
Question (5) What are villi? What is their location and function?
Answer
There are many finger-like projects found on the inner wall of small intestine. These finger-like outgrowths are called villi.
Villi are found on the inner wall of small intestine. The nutrients present in digested food are absorbed through villi to the blood stream. Villi increase surface area of small intestine which facilitates more absorption.
Question (6) Where is the bile produced? Which component of the food does it help to digest?
Answer
Bile is produced in liver. Bile helps in digestion of fats present in food.
Question (7) Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.
Answer
Cellulose, a type of carbohydrate, is found in plants. Cellulose can be digested by ruminants only and not by human.
Human cannot digest cellulose because they do not have rumen like ruminants and certain bacteria which acts upon cellulose in digestion are not present in human.
Question (8) Why do we get instant energy from glucose?
Answer
Glucose is a simple form of sugar and need not to go through the process of digestion. Because of this glucose absorbs instantly and release energy after reaching to the cell. This is the cause that we get instant energy from glucose.
Question (9) Which part of the digestive canal is involved in:
(i) Absorption of food _______.
Answer Absorption of food small intestine.
(ii) chewing of food ________.
Answer chewing of food mouth (buccal cavity).
(iii) killing of bacteria _______.
Answer killing of bacteria stomach.
(iv) complete digestion of food ______.
Answer complete digestion of food small intestine.
(v) formation of faeces ________.
Answer formation of faeces large intestine.
Question (10) Write one similarity and one difference between the nutrition in amoeba and human beings.
Answer
Similarity in amoeba and human being: Amoeba and human being both takes complex substances as food and both gets nutrition after broken down of complex substances of food into simpler one in the process of digestion.
Difference between amoeba and human being : Human being has mouth for ingestion and complex digestive system while mouth and digestive system both are absent in amoeba.
Question (11) Match the items of Column I with suitable items in Column II
| Column I | Column 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 |
Answer
| Column I | Column 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 |
Question (12) Label Fig. 2.11 of the digestive system.
Answer
Question (13) Can we survive only on raw, leafy vegetables/grass? Discuss.
Answer
No, we cannot survive only on raw, leafy vegetables/grass because raw, leafy vegetables/grass are rich in cellulose which we cannot digest as certain bacteria which can digest cellulose are absent in human beings.
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