Chapter 2: Nutrition in Animals

Science

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Chapter 1: Nutrition in Plants

Class VII

     NCERT Solutions

Question 1

Why do organisms need to take food?

Answer  

Every organism needs to take food to get energy for the growth, development and maintenance of their bodies.

 Question 2

 Distinguish between a parasite and a saprotroph.

 Answer

Question 3

 How would you test the presence of starch in leaves?

Answer

1. Take a potted plant with variegated leaves – for example, money plant or crotons.
2. Keep the plant in a dark room for three days so that all the starch gets used up.
3. Next , select a leaf cover its portion with a black strip paper and keep the plant in sunlight for about six hours.
4. Pluck the leaf from the plant. Mark the uncovered area in it and trace them on a sheet of paper. 
5. Dip the leaf in boiling water for a few minutes.
6. After this, immerse it in a beaker containing alcohol. 
7. Carefully place the above beaker in a water-bath and heat till the alcohol begins to boil.
8. Now dip the leaf in a dilute solution of iodine for a few minutes.
9. Take out the leaf and rinse off the iodine solution.
10. You observe that the presence of starch in different areas of the leaf which was uncovered.

Question 4

 Give a brief description of the process of synthesis of food in green plants.

Answer

Leaves are known as the food factories of plants. In plants, the synthesis of food occurs in leaves. Thus, all the raw materials (Water, Carbon dioxide and sunlight) must reach the leaves. Water and minerals are transported to the leaves by the vessels which run like pipes throughout the root, the stem, the branches and the leaves. Leaves with the help of a green pigment, chlorophyll capture the energy of the sunlight. This energy is utilised in the synthesise (prepare) of food from carbon dioxide and water.

Question 5

 Show with the help of a sketch that the plants are the ultimate source of food.

Answer  

All living beings depends on plants whether directly or indirectly. For example, the plant eater animals depends directly on plants but carnivore depends indirectly on plants. The following sketch shows some examples of plant dependency. 

Question 6

Fill in the blanks:

(a) Green plants are called _________________ since they synthesise their own food.

(b) The food synthesised by the plants is stored as _________________.

(c) In photosynthesis solar energy is captured by the pigment called ___________.

(d) During photosynthesis plants take in ______________________ and release __________________. 

Answer

(a) autotrophs

(b) starch.

(c) Chlorophyll.

(d) carbon dioxide and release oxygen.

Question 7

Name the following:

• A parasitic plant with yellow, slender and tubular stem.

(ii)  A plant that has both autotrophic and heterotrophic mode of nutrition.

• The pores through which leaves exchange gases.

Answer  

• Cuscuta
• Pitcher plant, Venus flytrap.
• Stomata

Question 8

 Tick the correct answer:

(a) Amarbel is an example of:

(i) autotroph  (ii) parasite  (iii) saprotroph  (iv) host

(b) A plant that traps and feeds on insects is:

(i) Cuscuta  (ii) china rose  (iv) pitcher plant  (iv) rose 

Answer

(a) Amarbel is an example of (ii) parasite. 

(b) The plant which traps and feeds on insects is (iv) pitcher plant.

Question 9

Match the items given in Column I with those in Column II:

Column I  Column II

Chlorophyll  Bacteria

Nitrogen  Heterotrophs

Amarbel  Pitcher plant

Animals  Leaf

Insects  Parasite

    Answer  

 Column I  Column II

Chlorophyll  Leaf

Nitrogen  Bacteria

Amarbel  Parasite

Animals   Heterotrophs

   Insects  Pitcher plant

Question 10

Mark ‘T’ if the statement is true and ‘F’ if it is false:

• Carbon dioxide is released during photosynthesis.
• Plants which synthesise their food themselves are called saprotrophs.
• The product of photosynthesis is not a protein.
• Solar energy is converted into chemical energy during photosynthesis.

Answer  

• (F)
• (T) 
• (F)
• (T)

Question 11

Choose the correct option:

Which part of the plant takes in carbon dioxide from the air for photosynthesis?

(i) Root hair  (ii) Stomata  (iii) Leaf veins  (iv) Sepals 

Answer

(ii) Stomata

Question 12

Choose the correct option from the following:

Plants take carbon dioxide from the atmosphere mainly through their:

(i) roots  (ii) stem  (iii) flowers  (iv) leaves 

Answer

(iv) leaves