Introduction
Before trying to attempt to answer the NCERT exercise questions, you should have a thorough understanding of class 7 Science chapter 1 i.e. ‘Nutrition in Plants‘.
If you haven’t understood the chapter yet, then worry not you can go through it easily and develop a crystal clear understanding of various concepts from our notes whose link has been provided below.
NCERT Exercise Questions & Answers
Que. 1 Why do organisms take food?
Ans. 1 Organisms take food to survive because it’s a basic need.
- Food provides energy to the body to work properly.
- Food is important for the growth and development of the organism.
- Food facilitates bodily damage repair.
- Various food nutrients also protect the body from infections as well, e.g. vitamin C, etc.
Que. 2 Distinguish between a parasite and a saprotroph
Ans. 2 The main difference(s) between a parasite and a saprotroph is-
| Parasite | Saprotroph |
| They are the organisms that live on or in the living organisms (called host) and get their food or nutrients from these living organisms | They are the organisms that acquire their nutrients from the dead and decaying matter. |
| e.g. Cuscuta, Leech, etc. | e.g. Indian pipe plant, mushrooms, etc. |
Que. 3 How would you test the presence of starch in leaves?
Ans. 3 The presence of starch in leaves can easily be tested with the help of a simple iodine test.
- Take a few fresh plant leaves.
- Remove the chlorophyll from the leaves by boiling them in alcohol.
- Then put a few drops of iodine onto the chlorophyll-less leaves.
- The iodine will impart a blue-black colour to the leaves which will confirm the presence of the starch in the leaves.
Que. 4 Give a brief description of the process of synthesis of food in green plants.
Ans. 4 Most green plants are autotrophic organisms meaning they synthesis their own food. Green plants prepare their food by the process of photosynthesis.
Photosynthesis is a process by which plants prepare their food by using carbon dioxide from air, water and minerals from the soil in the presence of sunlight and chlorophyll.
Que. 5 Show with the help of a sketch that plants are the ultimate source of food.
Ans. 5 Plants are the ultimate source of food on Earth and the Sun is the ultimate source of energy. So, don’t get these two facts confused. Plants prepare food by utilising solar energy and then this food is consumed by themselves and by others as well. Plants are known as the primary producers.
Here is how the energy flows from the Sun to various organisms across the food chain.
Que. 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.
Ans. 6 (a) Green plants are called autotrophs since they synthesise their own 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.
Que. 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. 7 (i) Cuscuta or Amarbel.
(ii) Insectivorous plants like pitcher plants and venus flytraps.
(iii) Stomata
Que. 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
Ans. 8 (a) (ii) parasite
(b) (iii) pitcher plant
Que. 9 Match the items given in Column I with those in Column II:
| Column I | Column II |
| Chlorophyll | Rhizobium |
| Nitrogen | Heterotrophs |
| Cuscuta | Pitcher plant |
| Animal | Leaf |
| Insect | Parasite |
Ans. 9 The matched items given in columns I and II are as such:
| Column I | Column II |
| Chlorophyll | Leaf |
| Nitrogen | Rhizobium |
| Cuscuta | Parasite |
| Animals | Heterotrophs |
| Insects | Pitcher plant |
Que. 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. 10 (i) Carbon dioxide is released during photosynthesis. (F)
(ii) Plants which synthesise their food are called saprotrophs. (F)
(iii) The product of photosynthesis is not a protein. (T)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T)
Que. 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. 11 (ii) Stomata takes in carbon dioxide from the air for photosynthesis.
Que. 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. 12 The correct option is (iv) leaves.
Que. 13 Why do farmers grow many fruits and vegetable crops inside large greenhouses? What are the advantages to the farmers?
Ans. 13 Farmers grow many fruits and vegetable crops inside large greenhouses because they provide the crop with suitable climate conditions and protect the crop from rodents, birds and adverse weather conditions.
Greenhouse provides the farmer control over the temperature, amount of sunlight, humidity, etc. which a farmer can utilize for the optimum growth of crops.
References & Credits
- Class 7th Science NCERT Textbook
- Image by brgfx on Freepik
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