Solutions For All Chapters Science Class 7
Q.1. Why do organisms take food?
Ans. Food is needed by all organisms for many purposes:
(a) The main function of food is to help in growth.
(b) Food provides energy for movements such as running, walking or raising our arm.
(c) Food is also needed for replacement and repairing damaged parts of body.
(d) Food gives us resistance to fight against diseases and protects us from infections
Q.3. How would you test the presence of starch in leaves?
Ans. The presence of starch in leaves can be tested by Iodine test. When we remove chlorophyll from leaf by boiling it in alcohol and then put 2 drops of iodine solution, its colour change to blue indicates the presence of starch.
Q.4. Give a brief description of the process of synthesis of food in green plants.
Ans. The green plants have chlorophyll in the leaves. The leaves use C02 and water to make food in presence of sunlight.
Q.5. Show with the help of a sketch that plants are the ultimate source of food.
Ans.
Q.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 absorbed by the pigment called ________________
(d) During photosynthesis plants take in ________________ and release ________________ .
Ans. (a) autotrophs (b) starch (c) chlorophyll (d) carbon dioxide, oxygen
Q.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.
Ans. (i) cuscuta (ii) Pitcher plant (iii) Stomata
Q.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:
(a) Cuscuta (ii) China rose {iii) Pitcher plant (iu) Rose
Ans. (a) (ii) Parasite (b) (iii) Pitcher plant
Q.9. Match the items given in Column I with those in Column II:
| Column-I | Column-II |
| Chlorophyll | Rhizobium |
| Nitrogen | Heterotrophs |
| Cuscuta | Pitcher plant |
| Animals | Leaf |
| Insects | Parasite |
Ans.
| Column-I | Column-II |
| Chlorophyll | Leaf |
| Nitrogen | Rhizobium |
| Cuscuta | Parasite |
| Animals | Heterotrophs |
| Insects | Pitcher plant |
Q.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)
Ans. (a) F (ii) F (iii) T (iv) T
Q.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
Ans. (ii) Stomata
Q.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
Ans. (iv) Leaves
Q.13.Why do farmers grow many fruits and vegetable crops inside large greenhouses? What are the advantages to the farmers?
Ans.
Fruits and vegetable crops are grown in large greenhouses because it protects crops from external climatic conditions and provides suitable temperature for the growth of crops.
Advantages to farmers while growing fruits and vegetable crops inside greenhouses are
It protects crops from diseases and adverse climatic conditions.
It protects crops from wind and rodents
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