NCERT Solutions for Class 7th: Ch 1 Nutrition in Plants Science

NCERT Solutions for Class 7th: Ch 1 Nutrition in Plants Science

Page No: 9

Excercise

1. Why do organisms need to take food?

Answer

Organisms need to take food to get energy and perform life process. The life process include nutrition, respiration, growth, excretion, reproduction and response to stimuli which can only be done by intake of food.

2. Distinguish between a parasite and a saprotroph.

Answer

Parasite	Saprotroph
The organism that grows on the body of another organism and derives nutrients from it is known as a parasite.	The organism that obtains nutrients from the dead or decaying organic matter is called saprotroph.
They take the readymade food from the host.	They take the digested and decayed food.
They directly feed on living organisms for their nutrition.	They feed on dead and decaying organism.
Examples- Cuscuta and orchids.	Examples- Fungi and some bacteria.

3. How would you test the presence of starch in leaves?

Answer

Steps to test the presence of starch in leaves :
Step 1: A fresh leaf is taken.
Step 2: The leaf is boiled in water for few minutes to kill the cells in the leaf.
Step 3: Now, dip this leaf in iodine solution.
Step 4: The color of the leaf will changes into blue black color when iodine is added to it which shows the presence of starch in it.

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

Answer

Photosynthesis is the process synthesis of food in the plants with the help of chlorophyll and carbon dioxide in the presence of sunlight.
Water and minerals present in the soil are absorbed by the roots and transported to the leaves by the vessels.
Carbon dioxide from air is taken through stomata present in leaves.
Leaves are the food factories of the plants which capture the energy of the sunlight with the help of chlorophyll. This energy is used to synthesize food from carbon dioxide and water.

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

Answer

The food chain shows that the plant is the ultimate producer. Only plant can produce food and rest of other organisms are directly or indirectly dependent on it.

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) Green plants are called autotrophs since they synthesise their own food.
(b) The food synthesised by the plants is stored as starch.
(c) In photosynthesis solar energy is captured by the pigment called chlorophyll .
(d) During photosynthesis plants take in carbon dioxide and release oxygen.

7. Name the following:
(i) A parasitic plant with yellow, slender and tubular stem.
(ii) A plant that has both autotrophic and heterotrophic mode of nutrition.
(iii) The pores through which leaves exchange gases.

Answer

(i) Cuscuta (Amarbel)
(ii) Pitcher plant
(iii) Stomata

8. Tick the correct answer:

(a) Amarbel is an example of:
(i) autotroph
(ii) parasite
(iii) saprotroph
(iv) host
► (ii) parasite

(b) The plant which traps and feeds on insects is:
(i) Cuscuta
(ii) china rose
(iii) pitcher plant
(iv) rose
► (iii) pitcher plant

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

Page No: 10

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

(i) Carbon dioxide is released during photosynthesis. (T/F)
► False

(ii) Plants which synthesise their food themselves are called saprotrophs. (T/F)
► False

(iii) The product of photosynthesis is not a protein. (T/F)
► True

(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)
► True

11. Choose the correct option from the following:

Which part of the plant takes in carbon dioxide from the air for photosynthesis?
 (i) Root hair
(ii) Stomata
(iii) Leaf veins           
(iv) Sepals
► (ii) Stomata

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
► (iv) leaves

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