Class 7 CBSE Biology Chapter 1: Nutrition in Plants Short Answer Questions
Biology Chapter 1: Nutrition in Plants Short Answer Questions
Each question carries 2-3 marks
1. What is photosynthesis? Write the word equation for photosynthesis.
2. Why are green plants called autotrophs?
3. What are stomata? What is their function?
4. Name the four main requirements for photosynthesis.
5. What is chlorophyll? Where is it found in plant cells?
6. Distinguish between autotrophic and heterotrophic nutrition.
7. What are parasitic plants? Give two examples.
8. Why do insectivorous plants eat insects? Name any two insectivorous plants.
9. What is meant by symbiotic relationship? Give one example.
10. How would you test a leaf for the presence of starch?
11. What is saprophytic nutrition? Give two examples of saprophytes.
12. Why do farmers add manure or fertilizers to the soil?
13. What is the role of guard cells in stomata?
14. How do plants obtain carbon dioxide for photosynthesis?
15. Explain why photosynthesis is important for all living organisms.
ANSWERS:
1. What is photosynthesis? Write the word equation for photosynthesis.
Answer: Photosynthesis is the process by which green plants make their own food using sunlight, carbon dioxide, and water in the presence of chlorophyll. During this process, plants convert light energy into chemical energy.
Word equation: Carbon dioxide + Water → Glucose + Oxygen (in the presence of sunlight and chlorophyll)
2. Why are green plants called autotrophs?
Answer: Green plants are called autotrophs because they can make their own food through photosynthesis. They do not depend on other organisms for their nutrition and can synthesize organic compounds from simple inorganic substances like carbon dioxide and water.
3. What are stomata? What is their function?
Answer: Stomata are tiny pores present on the surface of leaves, surrounded by two guard cells. Their main functions are to allow gas exchange (entry of carbon dioxide and exit of oxygen) and to control the loss of water vapor through transpiration.
4. Name the four main requirements for photosynthesis.
Answer: The four main requirements for photosynthesis are:
- Sunlight (light energy)
- Carbon dioxide (from air)
- Water (from soil through roots)
- Chlorophyll (green pigment in leaves)
5. What is chlorophyll? Where is it found in plant cells?
Answer: Chlorophyll is a green pigment that captures light energy for photosynthesis. It is found in chloroplasts, which are small structures present in plant cells, particularly in leaf cells. Chlorophyll gives plants their green color.
6. Distinguish between autotrophic and heterotrophic nutrition.
Answer: Autotrophic nutrition: Organisms make their own food from simple substances like carbon dioxide and water (e.g., green plants). Heterotrophic nutrition: Organisms cannot make their own food and depend on other plants or animals for nutrition (e.g., animals, fungi, and non-green plants).
7. What are parasitic plants? Give two examples.
Answer: Parasitic plants are those that cannot make their own food and obtain nutrients from other living plants (hosts) by growing on them. They harm the host plant by taking away its nutrients. Examples: Cuscuta (dodder), Rafflesia
8. Why do insectivorous plants eat insects? Name any two insectivorous plants.
Answer: Insectivorous plants eat insects because they grow in soil that lacks nitrogen and other essential nutrients. By consuming insects, they obtain the nitrogen and other minerals needed for their growth. Examples: Venus flytrap, Pitcher plant (Nepenthes)
9. What is meant by symbiotic relationship? Give one example.
Answer: Symbiotic relationship is an association between two different organisms where both benefit from each other. Neither organism is harmed, and both gain something useful from the partnership. Example: Lichens (formed by algae and fungi living together)
10. How would you test a leaf for the presence of starch?
Answer: To test for starch in a leaf:
- Boil the leaf in water to soften it
- Dip it in alcohol to remove chlorophyll
- Wash with water and place on a petri dish
- Add a few drops of iodine solution
- If starch is present, the leaf will turn blue-black
11. What is saprophytic nutrition? Give two examples of saprophytes.
Answer: Saprophytic nutrition is a mode of nutrition where organisms obtain food from dead and decaying organic matter. These organisms help in decomposition and recycling of nutrients in nature. Examples: Mushrooms, Bread mould (Rhizopus)
12. Why do farmers add manure or fertilizers to the soil?
Answer: Farmers add manure or fertilizers to the soil to replenish essential nutrients like nitrogen, phosphorus, and potassium. These nutrients are absorbed by plants from the soil and need to be replaced regularly to ensure healthy plant growth and good crop yield.
13. What is the role of guard cells in stomata?
Answer: Guard cells control the opening and closing of stomatal pores. When guard cells absorb water, they swell and the stomatal pore opens, allowing gas exchange. When they lose water, they shrink and the pore closes, preventing excessive water loss.
14. How do plants obtain carbon dioxide for photosynthesis?
Answer: Plants obtain carbon dioxide from the atmosphere through stomata present on the surface of leaves. Carbon dioxide enters the leaf through these tiny pores and reaches the cells containing chloroplasts where photosynthesis takes place.
15. Explain why photosynthesis is important for all living organisms.
Answer: Photosynthesis is important for all living organisms because:
- It produces oxygen that all living beings need for respiration
- It produces food (glucose) that serves as the primary source of energy for all life forms
- It removes carbon dioxide from the atmosphere, helping maintain ecological balance
- It forms the base of all food chains and food webs
Comments
Post a Comment