CBSE · NCERT · Class 7 Science · Chapter 2

NCERT Solutions: Class 7 Science Chapter 2 - Nutrition in Animals

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Chapter-wise NCERT intext questions and exercise answers for Nutrition in Animals, grounded in the official textbook.

Questions are taken verbatim from the NCERT textbook; answers were grounded against the chapter's content during generation. Items needing review are marked.
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Exercises 12
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1Exercises12 questions
Q.1Fill 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 __________.v
Answer:

(a) ingestion, digestion, absorption, assimilation and egestion
(b) liver
(c) digestive
(d) villi
(e) food vacuole

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Q.2Mark '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)v
Solution

Digestion of starch starts in the mouth because saliva contains digestive juice. The tongue mixes food with saliva. The gall bladder stores bile temporarily. Ruminants bring back cud and chew it again.

Answer:

(a) F
(b) T
(c) T
(d) T

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Q.3Tick (√) 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 (b) Water from the undigested food is absorbed mainly in the (i) stomach (ii) foodpipe (iii) small intestine (iv) large intestinev
Solution

Bile and pancreatic juice help digest fats in the small intestine. The large intestine absorbs water and salts from undigested food.

Answer:

(a) (iii) small intestine
(b) (iv) large intestine

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Q.4Match the items of Column I with those given in Column II: Column I: Food components, Carbohydrates, Proteins, Fats. Column II: Fatty acids and glycerol, Sugar, Amino acids.v
Answer:

Carbohydrates - Sugar; Proteins - Amino acids; Fats - Fatty acids and glycerol.

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Q.5What are villi? What is their location and function?v
Answer:

Villi are finger-like projections on the inner wall of the small intestine. They increase the surface area for absorption of digested food. Each villus has blood vessels that carry absorbed nutrients to all parts of the body.

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Q.6Where is the bile produced? Which component of the food does it help to digest?v
Answer:

Bile is produced by the liver and stored temporarily in the gall bladder. It helps in the digestion of fats.

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Q.7Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.v
Answer:

Cellulose can be digested by ruminants but not by humans. Ruminants have bacteria in a special part of the stomach that help digest cellulose, while humans do not have such cellulose-digesting bacteria in their digestive system.

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Q.8Why do we get instant energy from glucose?v
Answer:

Glucose is a simple sugar. It does not need much digestion and is absorbed quickly into the blood, so it can be used rapidly by body cells to release energy.

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Q.9Which 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 __________.v
Solution

The small intestine absorbs digested nutrients and completes digestion. Teeth in the mouth chew food. Hydrochloric acid in the stomach kills many bacteria. The large intestine absorbs water and forms faeces.

Answer:

(i) small intestine
(ii) mouth or buccal cavity
(iii) stomach
(iv) small intestine
(v) large intestine

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Q.10Write one similarity and one difference between the nutrition in Amoeba and human beings.v
Answer:

Similarity: both Amoeba and humans ingest, digest, absorb, assimilate and egest food. Difference: Amoeba engulfs food with pseudopodia and digests it in a food vacuole, while humans take food through the mouth and digest it in a well-developed digestive canal.

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Q.11Match the items of Column I with suitable items in Column II: Column I: Salivary gland, Stomach, Liver, Rectum, Small intestine. Column II: Bile juice secretion, Storage of undigested food, Saliva secretion, Acid release, Digestion is completed.v
Answer:

Salivary gland - Saliva secretion; Stomach - Acid release; Liver - Bile juice secretion; Rectum - Storage of undigested food; Small intestine - Digestion is completed.

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Q.13Can we survive only on raw, leafy vegetables/grass? Discuss.v
Answer:

No. Raw leafy vegetables provide vitamins, minerals and fibre, but they do not by themselves supply all nutrients in required amounts. Humans also cannot digest cellulose efficiently like ruminants. A balanced diet containing carbohydrates, proteins, fats, vitamins, minerals and water is needed for healthy survival.

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