Question

In an aquatic ecosystem, ___(A)____ is the major conduit for energy flow and in a
terrestrial ecosystem, a much larger fraction of energy flows through the___(B)_______.

• A. A - grazing food chain, B - detritus food chain
• B. A - food web, B - grazing food chain
• C. A - detritus food chain, B - grazing food chain
• D. A - grazing food chain, B - grazing food chain

Answer 1

The correct option is A A - grazing food chain, B - detritus food chain

A food chain refers to the sequence of transfer of energy in the form of food from organism to organism.

There are two types of food chains.

• Detritus food chain: It is also known as DFC, begins with dead and decaying organic material. It is composed of decomposers like bacteria and fungi (heterotrophic organisms) which meet their energy requirements by degrading dead organic matter (detritus).
• Grazing food chain: It is also known as GFC, begins with autotrophs like green plants, cyanobacteria, etc that are able to synthesise their own food and pass on the energy to herbivores and further to carnivores.

In an aquatic ecosystem, GFC is the major channel for energy flow and in a terrestrial ecosystem, a much larger fraction of energy flows through the DFC.

This is because, in aquatic ecosystems, there are a smaller number of producers and a high number of herbivores. Thus, making the grazing food chain to be dominant.

Most terrestrial ecosystems have a high number of producers and relatively lower number of herbivores than detritivores. Hence, the detrital food chain is dominant.