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

Nutrition in Plants

Question 1.
Why do organisms need to take food?

Solution:
Organisms need to take food to

  1.  get energy to do work.
  2.  build up body.
  3. repair damages in the body.
  4.  maintain the functions of the body.

Question 2.
Distinguish between a parasite and a saprotroph.

Solution:

ParasiteSaprotroph
   (i) Parasite derives nutrients from the living organisms.
(ii) Parasites mostly live on or in the host
They derive nutrients from dead and decaying organisms.
They live on dead and decaying stuff.

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

Solution:

  1. Take two healthy green potted plants of the same kind in order to remove all the starch from the leaves.
  2.  Keep one in the dark room (or in a black box) for 72 hours and the other in the sunlight.
  3.  Now, take one leaf from each of the plants.
  4. Put few drops of iodine solution on each of the leaves.
  5.  The leaf kept in the sunlight will turn blue-black due to presence of starch. The leaf kept in the dark will not turn blue-black because of the absence of starch.
    NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants image 1

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

Solution:
In green plants, the synthesis of food occurs by a process called photosynthesis. During photosynthesis, chlorophyll containing cells of the leaves, use carbon dioxide and water to synthesis carbohydrates in the presence of sunlight. The process can be represented by an equation.
NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants image 2
NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants image 3
During this process, oxygen is released. The carbohydrates formed ultimately get converted into starch. The presence of starch in leaves indicates the occurrence of photosynthesis. The starch is also a carbohydrate.

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

Solution:
Do your self ….

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

Solution:
(a) autotrophs
(b) starch
(c) chlorophyll
(d) carbon dioxide, oxygen.

Question 7.
Name the following :

  1.  A parasitic plant with yellow, slender and tubular stem.
  2.  A plant that has both autotrophic and heterotrophic mode of nutrition.
  3. The pores through which leaves exchange gases.

Solution:

  1. Cuscuta
  2.  Pitcher plant
  3.  Stomata.

Question 8.
Tick the correct answer :
(a) Amarbel is an example of :

  1.  autotroph
  2. parasite
  3.  saprotroph
  4.  host

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

  1.  cuscuta
  2.  china rose
  3.  pitcher plant
  4.  rose

Solution:
(a)-2 parasite
(b)-3 pitcher plant

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

Column IColumn II
ChlorophyllBacteria
NitrogenHeterotrophs
AmarbelPitcher plant
AnimalsLeaf
InsectsParasite

Solution:

Column IColumn II
ChlorophyllLeaf
NitrogenBacteria
AmarbelParasite
AnimalsHeterotrophs
InsectsPitcher plant

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

  1.  Carbon dioxide is released during photosynthesis. (T/F)
  2.  Plants which synthesise their food themselves are called saprotrophs. (T/F)
  3. The product of photosynthesis is not a protein. (T/F)
  4.  Solar energy is converted into chemical energy during photosynthesis. (T/F)

Solution:

  1.  F
  2.  F
  3.  T
  4.  T

Question 11.
Choose the correct option from the following :
Which part of the plant takes in carbon dioxide from the air for photosynthesis?

  1. Root hair
  2.  Stomata
  3.  Leaf veins
  4.  Sepals

Solution:
2  Stomata

Question 12.
Choose the correct option from the following :
Plants take carbon dioxide from the atmosphere mainly through their :

  1.  roots
  2.  stem
  3. flowers
  4.  leaves

Solution:
4  leaves.

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