NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals

Q1. 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: (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 juices which act on food.

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

(e) Amoeba digests 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. (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: (a) False, Digestion of carbohydrates, like starch, begins in the buccal cavity.

(b) True , The saliva breaks down the starch into sugars.

(c) True, bile juice that is stored in a sac called the gall bladder.

(d) True , In ruminants, bacteria present in rumen helps in digestion of cellulose.

Q3. Tick mark the correct answer in the following question:

(a) Fat is completely digested in the

(i) stomach

(ii) mouth

(iii) small intestine

(iv) large intestine

Answer: (a) Fat is completely digested in the

(iii) small intestine

Q3. Tick mark the correct answer in the following question:

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

(i) stomach

(ii) foodpipe

(iii) small intestine

(iv) large intestine

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

(iv) large intestine.

Q4. 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:

Q5. What are villi? What is their location and function?

Answer: The inner walls of the small intestine have thousands of finger-like outgrowths. These are called villi (singular villus).

The villi increase the surface area for absorption of the digested food. The surface of the villi absorbs the digested food materials. The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by the body. This is called assimilation.

Q6. Where is the bile produced? Which component of the food does it help to digest?

Answer: The liver secretes bile juice that is stored in a sac called the gall bladder.

The bile plays an important role in the digestion of fats.

Q7. Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also

Answer: Cellulose is the type of carbohydrate that can be digested by ruminants but not by humans because the cellulose of the food is digested by the action of certain bacteria which are not present in humans.

Q8. Why do we get instant energy from glucose?

Answer: The carbohydrates get broken into simple sugars like glucose.

In the cells, glucose breaks down with the help of oxygen into carbon dioxide and water, and it easily get absorbed in the blood hence we get instant energy from glucose.

Q9. 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: (i) absorption of food small intestine.

(ii) chewing of food buccal cavity.

(iii) the killing of bacteria stomach.

(iv) complete digestion of food small intestine.

(v) formation of faeces large intestine.

Q10. Write one similarity and one difference between the nutrition in amoeba and human beings

Answer: The similarity between the nutrition in amoeba and human beings is that both are heterotrophs, they derive their nutrition from other organisms.

The dissimilarity between them is that human beings have a complex digestive system where food gets digested in separate regions while in amoeba food is digested in a food vacuole.

Q11. 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: Matched items of column I with column II :

Q12. Label Fig. 2.11 of the digestive system

Answer: The labelled diagram is shown in the figure below:

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

Answer: No, we cannot survive only on raw, leafy vegetables, or grass. It is because humans are not able to digest the cellulose present in the grass or leafy vegetables due to the absence of cellulose-digesting enzymes.