Food chain and Trophic level — lesson. Biology CBSE Live product, Class 10 (2025-26).

Food chain and trophic levels

A food chain shows the linear flow of energy in an ecosystem.

For example, in a grassland, grass is eaten by a snail, the snail is eaten by a bird, and the bird is eaten by an eagle. It explains how organisms obtain energy and nutrients by consuming others, linking producers and consumers.

Food chain

Importance of food chain

Food chains help trace the flow of energy, show interactions among organisms, reveal inter-dependence, and explain the impact of population changes at different levels. They also help study how harmful non-biodegradable substances increase in concentration along the chain.

Trophic levels

Each step in a food chain is called a trophic level, and organisms at the same level have the same food habit. The main trophic levels are producers and consumers, and they can be represented in an ecological or energy pyramid.

Trophic levels or energy pyramid

First trophic level

Producers such as green plants and algae occupy the first level. They use photosynthesis to trap solar energy, of which only \(1%\) is converted into food. Their number is the highest among all levels.

Second trophic level

Primary consumers or herbivores such as deer and cattle occupy the second level. They use most of the energy for life functions, and only \(10% \)of it is stored and passed to the next level.

Third trophic level

Secondary consumers such as small carnivores and omnivores depend on primary consumers for food. Their population is smaller than herbivores.