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Nutrition In Plants

Class 7th Science CBSE Solution

Exercise
Question 1.

Why do organisms need to take food?


Answer:

All the organisms need to take food which provides us with the energy to perform daily activities like walking, breathing, etc and for the growth and the maintenance of the body.

The various components present in our food such as carbohydrates, proteins, fats, vitamins, and minerals provide energy to our body.

Thus, food intake by the organism is necessary for the survival of the organism in the surroundings.


Question 2.

Distinguish between a parasite and a saprotroph.


Answer:

Differences between a parasite and a saprotroph are:



Question 3.

How would you test the presence of starch in leaves?


Answer:

The presence of starch in leaves can be tested by iodine test. Iodine turns starch into blue-black colour. When few drops of dilute iodine solution is dropped on a boiled leaf, it becomes blue-black which proves the presence of starch in it.



Question 4.

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


Answer:


The Leaves are the food factories of the plant. the food is produced in the leaves of the plant in the manner given below:

1) Water and mineral present in the soil are absorbed by the roots and transported to the leaves.

2) Carbon dioxide from the air is taken in through the tiny pores present on the surface of the leaves.

3) The leaves of a plant have a green pigment chlorophyll. It helps the leave to capture the energy of the sunlight.

4) This energy is used to synthesise food from carbon dioxide and water.

This process of synthesis of food in the presence of sunlight is called photosynthesis.

The process of photosynthesis can be represented as:
Carbon dioxide + water Carbohydrates + Oxygen


Schematic diagram showing photosynthesis is given below


Question 5.

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


Answer: Plants are the basic source of food for all living organisms.
  • Plants prepare their food by the process of photosynthesis. Hence, they're called producers.
  • Every organism, primary consumer or a secondary consumer, needs food for getting energy to perform various tasks.
  • Primary consumers feed directly on the plants and secondary consumers eat primary consumers.
  • So, without plants primary consumers wouldn't be able to survive and without primary consumers secondary consumers wouldn't survive.
  • Hence, plants are the basic food source for all organisms.





Question 6.

Fill in the blanks:

a. Green plants are called _______ since they synthesize their own food.

b. The food synthesized 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.


Green plants can synthesize their own food by the process of photosynthesis.


b. starch.


The food prepared in the plant by the process of photosynthesis is glucose (a carbohydrate) then it gets stored in plant leaves in the form of starch.


c. chlorophyll.


Chlorophyll absorbs the light energy from the sun that is required for photosynthesis.


d. Carbon dioxide (CO2), Oxygen (O2).


In the process of photosynthesis, carbon dioxide gas is used and oxygen gas is produced.


Question 7.

Name the following:

i. A parasitic plant with yellow, slender and tabular stem.

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

iii. The pores through which leaves exchange gases.


Answer:

i. Cuscuta is a parasitic plant with yellow, slender and tabular stem.


ii. Pitcher plant has both autotrophic and heterotrophic mode of nutrition.


iii. The pores through which leaves exchange gases are called stomata.



Question 8.

Amarbel is an example of:
i. autotroph
ii. Parasite
iii. Saprotroph
iv. host


Answer:

Amarbel (Cuscuta) is an example of parasite.
It does not have chlorophyll. It gets readymade food from the plant on which it is climbing.



Question 9.

The plant which traps and feeds on insects is:
i. Cuscuta
ii. China rose
iii. pitcher plant
iv. Rose


Answer:

The plant which traps and feeds on insects is pitcher plant. Such insect-eating plants are called insectivorous plants.



Question 10.

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


Answer:

Chlorophyll : Leaf
The chlorophyll is found in the chloroplasts present in the plant cells in the leaves.


Nitrogen : Bacteria
The nitrogen fixing bacteria transform the atmospheric nitrogen into fixed nitrogen


Amarbel : Parasite


Amarbel is an example of parasite. It grows over host plants and is a leafless and rootless parasite.


Animals : Heterotrophs
Heterotrophs are those which cannot make their own food. They consume *autotrophs or other heterotrophs.
*Autotrophs are those which make their own food.


Insects : pitcher plant



Question 11.

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 synthesize their food themselves 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:

i. False.
In the process of photosynthesis, carbon dioxide gas is used and oxygen is released.


ii. False.
plants which synthesize their food themselves are called autotrophs.


iii. True.
In the process of photosynthesis, carbohydrate is produced.


iv. True.
During the process of photosynthesis, solar energy absorbed by the chlorophyll converted into chemical energy.


Question 12.

Choose the correct option from the following:

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

i. root hair

ii. Stomata

iii. Leaf veins

iv. Sepals.


Answer:

Plants need carbon dioxide for the process of photosynthesis. They take carbon dioxide from the air. Carbon dioxide enters the leaves through tiny pores present on the leaves’ surface called stomata.



Question 13.

Choose the correct option from the following:

Plants take carbon dioxide from the atmosphere mainly through their:

(i) root

(ii) stem

(iii) flowers

(iv) Leaves


Answer:

(iv) Leaves

Plants need carbon dioxide for the process of photosynthesis. They take carbon dioxide from the air. Carbon dioxide enters the leaves through tiny pores present on the leaves’ surface called stomata.