NCERT Class VII Science Solutions: Chapter 2-Nutrition in Animals Part 2

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NCERT Class 7 Science Chapter 2: Nutrition in Animals

Question 5:

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. Each villus has a network of thin and small blood vessels close to its surface. The surface of the villi absorbs the digested food materials.

This image shows longitudinal section through a villus

Longitudinal Section through a Villus

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Question 6:

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

Answer:

Liver (the largest gland in human body) secretes bile juice that is stored in a sac called the gall bladder. The bile helps in the digestion of fats.

As showing in images is a result for Liver

Result for Liver

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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) can be digested by ruminants but not by humans because ruminants have a large sac-like structure called rumen between the oesophagus and the small intestine. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans.

Question 8:

Why do we get instant energy from glucose?

Answer:

In the cells, glucose breaks down with the help of oxygen into carbon dioxide and water, and energy is released.

Question 9:

Which part of the digestive canal is involved in:

  1. Absorption of food ________________.

  2. Chewing of food ________________.

  3. Killing of bacteria ________________.

  4. Complete digestion of food ________________.

  5. Formation of faces ________________.

Answer:

  1. Absorption of food small intestine.

  2. Chewing of food buccal cavity (Mouth).

  3. Killing of bacteria stomach.

  4. Complete digestion of food small intestine.

  5. Formation of faces large intestine.

Question 10:

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

Answer:

  • Similarity: The basic process of digestion of food and release of energy is the same in amoeba as well as in human beings. In amoeba, Digestive juices are secreted into the food vacuole. They act on the food and break it down into simpler substances. Gradually the digested food is absorbed. Similarly, in human beings various digestive juices (mouth, stomach, intestine etc.) act on food and break it down to simpler substances.

  • Difference: The digestion process in amoeba is simple while in human beings it is a complex process. The process of ingestion and egestion are also quite different. Amoeba engulf its food by surrounding the food particle with its pseudopodia. The undigested food which is largely carbon dioxide gas is expelled outside by the vacuole. While in human beings, the food (which is complex substance) is taken inside the mouth and undergoes a complex process of digestion and absorption. Finally the undigested food it expelled in the form of faces.