Question

Describe various modes of nutrition. [3 MARKS]

Answer 1

Each point: 1 Mark

The different modes of nutrition are

1. Autotrophic Nutrition: The term autotrophic ('self-feeding') defines organisms which are able to use external sources of energy in the synthesis of their organic food materials.
2. Heterotrophic Nutrition: Heterotrophic organisms obtain their energy by breaking down substances obtained from the bodies of other organisms. This mode can be of following types:

• Holozoic nutrition: Some organisms take the food as a whole and break it inside the body. e.g. amoeba
• Saprophytic nutrition: Some organisms (called saprophytes) use dead and decaying plants and animals as a source of their food. They break down the complex molecules outside their body and then absorb them in the body. eg. fungi.
• Parasitic nutrition: Some organisms called parasites derive nutrients from plants and animals thereby affecting the host adversely. e.g. Cuscuta