Trophic Levels


 
 
Concept Explanation
 

Trophic Levels

Trophic Levels: Sometimes it is useful to study an ecosystem by grouping its organisms by their positions or levels in food chains. A level position in a food chain is called a trophic level. Energy and materials are transferred from one trophic level to another.

The producers in a food chain are at the first trophic level. The herbivores, which feed upon plants, are at the second trophic level. The carnivores, which feed upon herbivores, are at the third trophic level, and so on. So, each trophic level supports the one above it in terms of food. In a simple food chain of a grassland ecosystem, there are three trophic levels. Grass (producer) is at the first trophic level. Deer (herbivore) is at the second trophic level and lion (carnivore) is at the third trophic level.

What would happen if all the organisms of a trophic level are removed? The natural balance would be disturbed and the results would be disastrous. For example, in a grassland ecosystem, if all the carnivores (like lions) at the third trophic level are removed, the numbers of herbivores (like deer) in the trophic level below would go on increasing. Their numbers would soon be more than that can be supported by the plants of the region. They would eat up all the plants and turn the area into a desert.

Sample Questions
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Question : 1

In a food chain, herbivores constitute the _________________

Right Option : C
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Question : 2

The following groups of organisms represent different trophic levels. Which out of these four has greatest biomass ?

Right Option : C
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Question : 3

In aquatic ecosystem, biomass is least at which trophic level ?

Right Option : C
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