Question1. Fill in the blanks:
(a) The main steps of nutrition in humans are __________, __________, __________, _________ and __________.
Solution 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 __________.
Solution 1(b):
The largest gland in the human body is ___liver___.
(c) The stomach releases hydrochloric acid and ___________ juices which act on food.
Solution 1(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 _________.
Solution 1(d):
The inner wall of the small intestine has many finger-like outgrowths called ___villi___.
(e) Amoeba digests its food in the ____________ .
Solution 1(e):
Amoeba digests its food in the ___food 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)
Solution 2(a):
False.
(b) The tongue helps in mixing food with saliva. (T/F)
Solution 2(b):
True.
(c) The gall bladder temporarily stores bile. (T/F)
Solution 2(c):
True.
(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/F)
Solution 2(d):
True.
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
Solution 3(a):
Small intestine.
(b) Water from the undigested food is absorbed mainly in the
(i) stomach (ii) food pipe (iii) small intestine (iv) large intestine
Solution 3(b):
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
Solution (4):
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 are their location and function?
Solution (5):
Villi are finger-like outgrowths on the inner walls of the small intestine. The villi increase the surface area for the absorption of the digested food. These villi have a network of thin and small blood vessels close to their 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?
Solution (6):
The bile juice is produced by the liver. 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.
Solution (7):
The name of the carbohydrate is cellulose. It is digested by ruminants but not by humans because enzymes which digest cellulose are not present in humans.
Question 8. Why do we get instant energy from glucose?
Solution (8):
Glucose is the simplest form of carbohydrates and easily gets absorbed by the blood and hence provides instant energy.
Question 9. Which part of the digestive canal is involved in
(i) absorption of food ________________.
Solution 9 (i):
Absorption of food __small intestine__.
(ii) chewing of food ________________.
Solution 9 (ii):
Chewing of food __buccal cavity__
(iii) killing of bacteria ________________.
Solution 9 (iii):
Killing of bacteria __stomach__
(iv) complete digestion of food ________________.
Solution 9 (iv):
Complete digestion of food ___small intestine___.
(v) formation of faeces ________________.
Solution 9 (v):
Formation of faeces __large intestine__.
Question 10. Write one similarity and one difference between the nutrition in amoeba and human beings.
Solution 10:
Similarity: Humans and amoeba both need digestive juices for the digestion of food.
Difference: Humans need to chew the food on the other hand amoeba do not need to chew the food.
Question 11. Match the items in 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 plant waste plant waste
(e) Small intestine (v) Digestion is completed
(f ) Large intestine (vi) Absorption of water
(vii) Release of faeces
Solution 11:
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
Solution 12:
Question 13. Can we survive only on raw, leafy vegetables/grass? Discuss.
Solution 13:
No, we cannot survive for a very long time by eating only leafy and raw vegetables/grass. We need a balanced diet to live a long and healthy life. Also, the grass contains cellulose which cannot be digested by the human digestive system.