NCERT Solutions —
Class 7 Science Chapter 1 Nutrition in Plants
Introduction
All living things need food for energy, growth and repair. Plants can make their own food using sunlight, water and carbon dioxide. This process is called photosynthesis. Animals and many other organisms get food directly or indirectly from plants.
Chapter 1 Nutrition in Plants Questions – Answers
NCERT Solutions
Q1. Why do organisms take food?
Answer: Organisms need food to get energy for work, growth and repair. Plants make food by themselves. Animals eat plants or other animals to get energy.
Q2. Distinguish between a parasite and a saprophyte.
| Parasite | Saprophyte |
|---|---|
| Lives on or inside a living host and takes food from it (may harm host). Example: Cuscuta. | Feeds on dead or decaying matter and helps in decomposition. Example: many fungi. |
Q3. How would you test the presence of starch in leaves?
Answer: Keep one plant in the dark and one in sunlight. Pluck a leaf from each, boil and test with iodine. If the leaf turns blue-black, starch is present. The leaf kept in light will show starch.
Q4. Briefly describe the synthesis of food in green plants (photosynthesis).
Answer: Plants use water (from roots), carbon dioxide (from air) and sunlight captured by chlorophyll in leaves to make food. Oxygen is released as a byproduct.
Simple form: Carbon dioxide + Water —(Sunlight + Chlorophyll)—> Food (carbohydrate) + Oxygen
Q5. Explain how plants ar the ultimate source of food.
Answer: Plants make their own food and form the base of all food chains. Herbivores eat plants; carnivores eat herbivores. So every animal depends directly or indirectly on plants.
Q6. Fill in the blanks
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Green plants are called autotrophs.
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The food prepared by plants is stored as starch.
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In photosynthesis, solar energy is absorbed by chlorophyll.
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During photosynthesis, plants take in carbon dioxide and release oxygen.
Q7. Name the following
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Parasitic plant with yellow, thin stems: Cuscuta.
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Partly autotrophic plant (traps insects): Pitcher plant.
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Pores on leaves for gas exchange: Stomata.
Q8. Choose the correct answer
(a) Cuscuta is an example of a parasite.
(b) The plant which traps insects is the pitcher plant.
Q9. Match the following
| Chlorophyll | Leaf |
| Nitrogen | Rhizobium |
| Cuscuta | Parasite |
| Animals | Heterotrophs |
| Insects | Pitcher plant |
Q10. True or False
- Carbon dioxide is released during photosynthesis. — False (Plants take CO₂).
- Plants that make their own food are called saprotrophs. — False (They are autotrophs).
- The product of photosynthesis is not protein. — True (it is mainly carbohydrate).
- Solar energy is converted into chemical energy during photosynthesis. — True.
Q11. 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
Q12. Which part takes in carbon dioxide?
Answer: The leaves, through openings called stomata, take in carbon dioxide from the air for photosynthesis.
Q13. Why do farmers use greenhouses?
Answer: Greenhouses provide a controlled, warm and protected place for crops. They protect plants from bad weather and pests and help farmers get better yields.
Quick Summary
Photosynthesis helps plants make food using sunlight, water and carbon dioxide. Plants are autotrophs and are the main source of food in nature. Some plants are parasitic or insectivorous and do not fully rely on photosynthesis.
