CLASS :- 7
SUBJECT :- SCIENCE
CHAPTER: - NUTRATION IN PLANT (NCERT Solutions)
Question 1.
Why do organisms need to take food?
Solution:
Food is needed by all living organisms for the following purposes :
1. It is meant for the general growth and development of an organism. If it is not an insufficient amount, then it shows insufficient growth and development, along with hunger signs.
2. It is meant to provide energy. We need energy for movements such as running, walking, or raising our arms.
3. It is also needed by living beings for repairing of their damaged parts.
4. It gives us resistance against diseases and protects us from infections.
Question 2.
Distinguish between a parasite and a saprotroph.
Solution:
Parasite | Saprotroph |
(i) Parasite derives nutrients from living organisms.
| They derive nutrients from dead and decaying organisms |
(ii) Parasites mostly live on or in the host | 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 darkroom (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 the presence of starch.
6. The leaf kept in the dark will not turn blue-black because of the absence of starch.
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.
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. Starch is also a carbohydrate.
Question 5.
Show with the help of a sketch that the plants are the ultimate source of food.
Solution:
Question 6.
Fill in the blanks:
1. Green plants are called ………………. since they synthesize their own food.
2. The food synthesized by the plants is stored as ……………….
3. In photosynthesis, solar energy is captured by the pigment called ……………….
4. During photosynthesis plants take in ………………. and release.
Solution:
1. autotrophs
2. starch
3. chlorophyll
4. carbon dioxide, oxygen.
Question 7.
Name the following:
1. A parasitic plant with a yellow, slender, and tubular stem.
2. A plant that has both autotrophic and heterotrophic modes 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 :- I | COLUMN :- II |
Chlorophyll | Bacteria |
Nitrogen | Heterotrophs |
Amarbel | Pitcher plant |
Animals | Leaf |
Insects | Parasite |
SOLUTION
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 :
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