Chapter 1:
Nutrition in Plants

Class 7 Science | CBSE Curriculum

Nutrition in Plants explains how plants prepare their own food via photosynthesis, the role of chlorophyll, and other modes of nutrition like parasitic, saprotrophic, and insectivorous plants. Includes key concepts like stomata, symbiosis, and nitrogen fixation.

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Time:
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Quick Revision: Nutrition in Plants

  • Nutrients: Components of food (carbohydrates, proteins, fats, vitamins, minerals) necessary for our body.
  • Nutrition: The mode of taking food by an organism and its utilisation by the body.
  • Autotrophs: Organisms that make their own food from simple substances (e.g., green plants).
  • Heterotrophs: Organisms that depend on others for food (e.g., animals, humans).
  • Photosynthesis: The process by which plants synthesise food using chlorophyll, sunlight, carbon dioxide, and water. Equation: Carbon Dioxide + Water → (in presence of sunlight & chlorophyll) Carbohydrates + Oxygen.
  • Chlorophyll: A green pigment present in leaves that captures solar energy.
  • Stomata: Tiny pores on the leaf surface, surrounded by guard cells, for gas exchange.
  • Parasites: Organisms that take readymade food from a living host (e.g., Cuscuta).
  • Insectivorous Plants: Plants that trap and digest insects to obtain nutrients (e.g., Pitcher plant).
  • Saprotrophs: Organisms that take nutrients from dead and decaying matter (e.g., fungi, mushrooms).
  • Symbiosis: A relationship where two different organisms live together and share shelter and nutrients (e.g., Lichen, Rhizobium in leguminous plants).
  • Replenishing Soil: Fertilisers, manures, and nitrogen-fixing bacteria like Rhizobium add nutrients back to the soil.

Chapter Summary: Nutrition in Plants

All organisms need food for energy, growth, and body maintenance. Plants are unique as they can synthesise their own food through photosynthesis, using sunlight, water, and carbon dioxide. They are called autotrophs. The green pigment chlorophyll, found in leaves, is essential for capturing light energy. The process occurs mainly in leaves and releases oxygen as a byproduct. The food is stored as carbohydrates like starch.

However, not all plants follow this mode. Some, like Cuscuta, are parasites that derive nutrition from a host plant. Others, like the Pitcher plant, are insectivorous, trapping insects to supplement their nutrient intake, especially nitrogen. Many fungi and bacteria adopt a saprotrophic mode of nutrition, feeding on dead and decaying matter. Some organisms live in mutually beneficial symbiotic relationships, such as lichens (algae and fungi) and Rhizobium bacteria in the roots of leguminous plants. Rhizobium converts atmospheric nitrogen into a usable form for the plant, enriching the soil. This chapter highlights the diversity in how living things, particularly plants, obtain their food.