Class 7 - Biology - Nutrition in Plants

Question 1:

Why do organisms need to take food?

 

Answer:

All organisms need to take food to get energy for the growth, development, locomotion and maintenance of their bodies.

 

 

Question 2: Distinguish between a parasite and a saprotroph.

 

 Answer:

Difference between a parasite and a saprotroph

s.No

Parasite

Saprotroph

1.

Organisms derive nutrition from the body of other living organisms (host) are parasites.

Plants which derive nutrition from dead and decaying organisms are called saprotrophs.

2.

Example: Cuscata

Example: Mushrooms

 

 

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. Now 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 various 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 the food factories of plants. The synthesis of food in plants occurs in leaves.

Therefore, all the raw materials (Water, Carbon dioxide and sunlight) must reach there.

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.

The leaves have a green pigment called chlorophyll which helps leaves to capture the energy of the sunlight.

This energy is used to synthesise (prepare) food from carbon dioxide and water. This process is termed as ‘Photosynthesis’.

 

 

Question 5:

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

 

Answer:

All the living being depends on plants whether directly or indirectly.

For example, the plant eater animals depend directly on plants but carnivore depends indirectly on plants.

The following sketch shows some examples of plant dependency.

 

 Class_7_Bio_Nutrition_in_Plants_Plant_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 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.

 

 

 

Question 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) A parasitic plant with yellow, slender and tubular stem – Cuscuta

(ii) A plant that has both autotrophic and heterotrophic mode of nutrition - Pitcher plant, Venus flytrap.

(iii) The pores through which leaves exchange gases – Stomata

 

 

Question 8:

Tick the correct answer:

(a) Amarbel 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 (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:

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

(ii) Plants which synthesise 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) Carbon dioxide is released during photosynthesis. (False)

(ii) Plants which synthesise their food themselves are called saprotrophs. (False)

(iii) The product of photosynthesis is not a protein. (True)

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

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