Ch 1 explains how plants obtain nutrition. Green plants are autotrophs — they make food through photosynthesis. Some plants are heterotrophs: parasites, insectivorous plants, and saprotrophs.
Green plants make food using sunlight, CO₂, and water in the presence of chlorophyll. The process occurs mainly in leaves (the food factories). Equation: CO₂ + H₂O → (sunlight, chlorophyll) → Glucose + O₂. Starch is tested using iodine solution (turns blue-black).
Parasites: obtain food from a living host (Cuscuta/amarbel wraps around other plants). Insectivorous plants: trap insects for nitrogen (Venus flytrap, pitcher plant). Saprotrophs: feed on dead/decaying matter (mushrooms, bread mould). Symbiosis: mutual benefit (lichens = algae + fungi).
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Leaves contain chlorophyll, a green pigment found in chloroplasts. Chlorophyll absorbs red and blue light and reflects green light, making leaves appear green. Chlorophyll is essential for photosynthesis.
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