NCERT Solutions for Class 7 Science Chapter 1:Nutrition in Plants

NCERT Solutions for Class 7 Science Chapter 1 Exercise Question

Question 1.

Why do organisms take food?

Answer 1

All organisms take food to get energy for their life processes. So that they can perform many function like repairing damaged parts of body and do all activities such as playing, running, walking, studying, etc. require energy.

Question 2.

Distinguish between a parasite and a saprophyte.

Answer 2

Question 3.

How would you test the presence of starch in leaves?

Answer 3

Iodine solution is used to test leaves for the presence of starch. You need to:
Step 1:Boilinga plant leaf in water for 30 seconds (this stops its chemical reactions)
Step 2:boiling it in ethanol for a few minutes (this removes most of its colour)
Step 3:wash with water and spread onto a white tile
Step 4:add iodine solution from a dropping pipette
After a few minutes, the parts of the leaf that contain starch turn blue-black

Question 4.

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

Answer 4

Green plants use a process called as photosynthesis to prepare their food. As we know leaves are the food factory of green plant and photosynthesis occurs in leaves so all raw material must reach there.So Water is taken from the roots of the plant, and it is transported to leaves of the plant.And Carbon dioxide from air enter the leaves through pores know as stomata. The leaves contain green pigment know as chlorophyll which helps to hold sunlight.This energy is used to prepare food from carbon dioxide and water.And in the process hydrogen combines with Oxygen and Hydrogen to form carbohydrates.

Question 5.

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

Answer 5

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 6

(a) Green plants are called autotrophs since they synthesise their food.
(b) The food synthesised by plants is stored as starch.
(c) In photosynthesis, solar energy is absorbed by the pigment called chlorophyll.
(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 6

Question 8.

Tick the correct answer:
(a) Cuscuta is an example of:
(i) autotroph
(ii) parasite
(iii) saprotroph
(iv) host
(b) The plant which traps and feeds on insects is:
(i) Cuscuta
(ii) china rose
(iii) pitcher plant
(iv) rose

Answer 8

a)(ii) Parasite
b)(iii) pitcher plant

Question 9.

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

Answer 9

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 10.

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 11.

(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 12.

(iv) leaves