NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants

Exercise

Question 1. Why do organisms take food?

Answer:- All organism need to take food to get energy for their growth, development and maintenance.

Question 2. Distinguish between a parasite and a saprotroph.

Answer:-

Parasites	Saprophytes
Parasites live on or in a host and get its food at the expense of its host	Acquire nutrients from dead and decaying matter
Example: Tapeworm, roundworm	Example: Mushrooms, Fungi

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

Answer:- Iodine testing can be used to determine whether or not leaves contain starch. Add two drops of iodine solution to the leaf, the colour changes to blue, indicating the presence of starch.

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

Answer:- Chlorophyll is found in the leaves of green plants. In the presence of sunlight, the leaves produce food using CO2 and water.

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

Answer:- Every living being on this eart is directly or indirectly depends on plants for their food requirements. For example herbivores eat plants and its products directly whereas carniovores eats plant eaters. Thus the following sketch shows that the plants are the ultimate source of food.

Question 6. Fill in the blanks:

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

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

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

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

Answer:-

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

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

(d) During photosynthesis plants take in carbon dioxide and release oxygen gas.

Question 7. Name the following:

(i) A parasitic plant with yellow, slender and branched stem.

(ii) A plant that is partially autotrophic.

(iii) The pores through which leaves exchange gases.

Answer:-

(i). Cuscuta

(ii). Pitcher plant

(iii). Stomata

Question 8. Tick the correct answer:

(a) Cuscuta is an example of:

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

Answer:- (ii) parasite

(b) The plant which traps and feeds on insects is:

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

Answer:- (iv) pitcher plant

Question 9. Match the items given in Column I with those in Column II:

Column I	Column II
Chlorophyll	Rhizobium
Nitrogen	Heterotrophs
Cuscuta	Pitcher plant
Animals	Leaf
Insects	Parasite

Answer:-

Column I	Column II
Chlorophyll	Leaf
Nitrogen	Rhizobium
Cuscuta	Parasite
Animals	Heterotrophs
Insects	Pitcher plant

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

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

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

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

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

Answer:-

False
False
True
True

Question 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) Petals

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

Question 13. Why do farmers grow many fruits and vegetable crops inside large green houses? What are the advantages to the farmers?

Answer:- Green house provide favourable climatic conditions like suitable temperature for these crops. Advantages to farmers while growing fruits and vegetable crops inside greenhouses are:-

The crops grow well.
It protects crops against pathogens and bad climatic conditions.
It protects crops from the wind and rodents