Chapter 1 : Nutrition in Plants
1. Why do organisms need to take food?
All living beings require food to grow, gain energy, repair worn-out parts, and carry out life activities. Plants make their own food, while animals eat plants or other animals to get nutrients
2. Distinguish between a parasite and a saprophyte.
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Parasite: Lives on (or inside) a living host and harms it (e.g., Cuscuta).
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Saprophyte: Lives on dead material and breaks it down for nutrients (e.g., mushrooms)
3. How do you test for starch in leaves?
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Keep one plant in sunlight, another in the dark for a few days.
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Pluck leaves, dip in boiling water, then clean with alcohol.
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Apply iodine solution—sun-grown leaves turn blue-black, indicating starch; dark-kept ones don’t
4. Describe how green plants synthesize food.
Through photosynthesis, green plants use sunlight, carbon dioxide, and water to create glucose (food) and release oxygen. This process takes place in the chloroplasts of leaf cells .
5. Apart from photosynthesis, how else do some plants get food?
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Saprotrophs like fungi absorb nutrients from dead organic matter.
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Parasitic plants (e.g., Cuscuta) steal food from host plants.
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Insect-eating (insectivorous) plants catch insects for nitrogen—e.g., pitcher plants
6. How do plants get nutrients besides carbohydrates?
Plants absorb vital minerals—like nitrogen, phosphorus, and potassium—from the soil via their roots. Nitrogen-fixing bacteria (e.g., Rhizobium in pulses) enrich the soil naturally
7. Explain how soil nutrients are replenished.
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Naturally: Through nitrogen-fixing bacteria and decaying organic material.
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Artificially: By adding manure or fertilizers that replenish essential nutrients
🔍 Quick Extra Questions
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Q: Why is chlorophyll essential for photosynthesis?
A: It captures light energy—without it, leaves can’t produce starch . -
Q: What is an autotroph?
A: An organism that makes its own food (e.g., green plants) -
Q: Define stomata.
A: Tiny pores on leaves that allow gases (CO₂ in, O₂ out) and release wate