Nutrition in Plants and Animals: Autotrophic and Heterotrophic Modes

Modes of Nutrition

Nutrition is the process by which organisms obtain and use food for energy, growth and repair. There are two broad modes: autotrophic and heterotrophic.

Autotrophic Nutrition

Autotrophs (mainly green plants) make their own food through photosynthesis, using sunlight, carbon dioxide and water to produce glucose and oxygen: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.

Heterotrophic Nutrition

Heterotrophs (animals and fungi) cannot make their own food; they obtain it by feeding on plants or other animals. Types include herbivores (plant eaters), carnivores (meat eaters), omnivores (both) and saprophytes (feed on dead/decaying matter).

Digestion in Animals

Digestion breaks down complex food substances into simpler soluble forms that can be absorbed into the bloodstream. Key stages are ingestion, digestion, absorption, assimilation and egestion.

Essential Nutrients

• Carbohydrates - energy
• Proteins - growth and repair
• Fats and oils - energy storage and insulation
• Vitamins and minerals - regulate body processes
• Water and fibre - support digestion and hydration