NCERT Solutions for Class 7 Science - Nutrition in Animals

Exercises

Q1. Fill in the blanks.
(a) The main steps of nutrition in humans are _____, ____, _____, _____ and ______.
Ans: The main steps of nutrition in humans are Ingestion, digestion, absorption, assimilation and egestion.

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

(c) The stomach releases hydrochloric acid and _____ juices which act on food.
Ans: 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 _______.
Ans: The inner wall of the small intestine has many finger-like outgrowths called villi.

(e) Amoeba digests its food in the ________
Ans: Amoeba digest its food in the food vacuole.

Q2. Mark T if the statement is true and F if it is false.
(a) Digestion of starch starts in the stomach.
Ans: False

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

(c) The gallbladder temporarily stores bile.
Ans: True

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

Q.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
Ans: (iii) Small intestine

(b) Water from the undigested food is absorbed mainly in the
(i) stomach
(ii) food pipe
(iii) Small intestine
(iv) Large intestine
Ans: (iv) Large intestine

Q4. Match the column

Ans:

Q5. What are villi? What are their location and function?
Ans: Villi is the finger-like projections. These are found in the inner walls of small intestine. It helps in absorption of the digested food.

Villi

Q6. Where is the bile produced? Which component of the food does it digest?
Ans: Bile is produced in the liver. Bile helps in digestion of fats.

Q7. Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.
Ans: Cellulose is the type of carbohydrates which is digested in ruminants but not in humans. Ruminants have a large sac–like structure between the small intestine and large intestine, in which cellulose of the food is digested by the action of certain bacteria. Such structure is not present in humans. Hence humans cannot digest cellulose while ruminants can.

Q8. Why do we get instant energy from glucose?
Ans: Glucose is a simple sugar so there is no need for digestion. It directly reaches the cells where it gives energy after respiration.

Q.9. Which part of the digestive canal is involved in:
(a) Absorption of food ________.
Ans: Absorption of food Small Intestine.

(b) Chewing of food ________.
Ans: Chewing of food Buccal cavity.

(c) Killing of bacteria ________.
Ans: Killing of bacteria Stomach.

(d) Complete digestion of food _______.
Ans: Complete digestion of food Small intestine.

(e) Formation of faeces _________.
Ans: Formation of faeces Large Intestine.

Q10. Write one similarity and one difference between the nutrition in amoeba and human beings.
Ans: Similarity: Both Amoeba and human have holozoic type of nutrition.
Difference: Human beings have complex structure for the ingestion, digestion and egestion of food while Amoeba has simple process in which it engulfs the with the help of pseudopodia and food get trapped in food vacuoles.

Q11. Match the following column

Ans:

Q12. Label the diagram of the digestive system.

Ans:

Q13. Can we survive only on raw, leafy vegetables/grass? Discuss.
Ans: 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.