NCERT Solutions Class 7 Science Chapter 1 PDF
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Here a brief discussion on NCERT Class 7 Science Chapter 1 Nutrition in Plants is done. Some major components of food are carbohydrates, fats, lipids, proteins, minerals, and vitamins. These nutrients are very essential for our body. Based on the mode of nutrition of various organisms it can be classified as autotrophs and heterotrophs.
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- Autotrophs make their own food. For example, plants.
- Heterotrophs do not make their own food. Example, animals rely on plants and other animals for food.
Plants make their food by the process of photosynthesis.
Check out Class 7 Science Chapter 1 NCERT Solution PDF given below for a thorough understanding of the topics.
1. Why do organisms take food?
Answer:
All organisms require energy for their life processes. Plants prepare their food and acquire nutrients from abiotic components like soil, air, water and sunlight. On the other hand, animals need to get food from either plants or other animals to obtain nutrients; hence animals need to take food to acquire nutrients and energy.
2. Distinguish between a parasite and a saprophyte.
Answer:
| Saprophytes | Parasites |
| Acquire nutrients from dead and decaying matter | Parasites live on or in a host and get its food at the expense of its host |
| Example: Fungi | Example: roundworm |
3. How would you test the presence of starch in leaves?
Answer:
Take two potted plants of the same kind. Keep one in the dark for 72 hours and the other in sunlight. Perform the iodine test with the leaves of both the plants as given below. Now leave the pot which was earlier kept in the dark, undisturbed for 3 – 4 days and perform the iodine test again on its leaves.
Iodine test:
Put iodine solution on the leaf
Observation:
Blue-black colour will be observed on the leaves of the plant kept in sunlight, which indicates the presence of starch.
Blue-black colour will not be observed on the leaves of plant kept in the darkroom. This indicates the absence of starch.
4. Give a brief description of the process of synthesis of food in green plants.
Answer :
Photosynthesis is defined as the process in which the chlorophyll-containing plant cells synthesise food in the form of carbohydrates, using carbon dioxide and water in the presence of solar energy.
Photosynthesis Sources of raw materials required for photosynthesis:
(a) Water is taken in from the roots of the plant and is transported to the leaves.
(b) Carbon dioxide from the air enters the leaves through the tiny pores called stomata and diffuses to the cells containing chlorophyll.
(c) Solar energy is used to break water into hydrogen and oxygen. This hydrogen is combined with carbon dioxide to form food for the plants, which is ultimately used by the animals as well. Thus, photosynthesis can be represented by the following equation.
5. Show with the help of a sketch that the plants are the ultimate source of food.
Answer :
Photosynthesis
6. Fill in the blanks:
(a) Green plants are called _________________ since they synthesise their own food.
(b) The food synthesised by plants is stored as _________________.
(c) In photosynthesis solar energy is absorbed by the pigment called ___________.
(d) During photosynthesis plants take in ______________________ and release __________________ gas.
Answer:
(a) Green plants are called autotrophs since they synthesise their food.
(b) The food synthesised by plants is stored as starch.
(c) In photosynthesis, solar energy is absorbed by the pigment called chlorophyll.
(d) During photosynthesis, plants take in Carbon dioxide and release Oxygen gas.
7. Name the following:
i) A parasitic plant with the yellow, slender and branched stem.
ii) A plant that is partially autotrophic.
iii) The pores through which leaves exchange gases.
Answer:
i) Cuscuta
ii) Pitcher plant
iii) Stomata
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:
(i) Cuscuta
(ii) china rose
(iii) pitcher plant
(iv) rose
Answer:
(ii) Parasite
(iii) pitcher plant
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 |
Answer:
| Column- I | Column-II |
| Chlorophyll | Leaf |
| Nitrogen | Rhizobium |
| Cuscuta | Parasite |
| Animals | Heterotrophs |
| Insects | Pitcher plant |
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)
Answer:
False
False
True
True
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
Answer:
(ii) Stomata
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