Question

Detritus food chain begins with:
(a) Bacteria
(b) Viruses
(c) Algae
(d) Protozoa

Answer 1

Hint: Detritus food chain begins with detritus or dead organic matter that is decomposed by decomposers which are unicellular prokaryotic microorganisms that were among the first life to appear on earth.

Complete answer:
The Detritus food chain (DFC) starts with detritus or dead organic matter. It is made up of decomposers which are heterotrophic organisms mainly bacteria and fungi. Detritivores act over it. Therefore, the food energy present in the detritus is passed into them. Then these detritivores and decomposers are consumed by smaller carnivores which in turn become food for larger carnivores and so on.
A common detritus chain involves: $Detritus\longrightarrow Earthworm\longrightarrow Sparrow\longrightarrow Falcon$ - Food chain is a sequence of living organisms which involves the transfer of food energy from producers, though a series of organisms with the repeated eating and being eaten. - Each level or step in the food chain where the transfer of energy takes place is called a trophic level.
Types of the food chains are the Grazing food chain, the Detritus food chain, and the Parasitic food chain. - Grazing food chain (GFC) or Predator Food chain: It consists of producers, consumers, and decomposers. Here the source of energy is the sun. - Parasitic food chain: Also known as Auxiliary food chain. Here the size of the organism finally reduces at the higher trophic level. - Detritus Food Chain may be connected to the Grazing Food Chain at some levels. Some of the GFC animals prey on the organisms of DFC. This interconnection between two food chains is known as a food web.

So, the correct answer is, ‘(a) Bacteria.’

Note: - Energy flow is always unidirectional or one way in any food chain. Thus, the energy once passed doesn’t pass back to the lower level. - In terrestrial ecosystems, a much larger fraction of energy flows through a Detritus Food Chain than through Grazing Food Chain (GFC). - Grazing Food Chain is a major conduit of energy flow in the aquatic ecosystem. - Parasitic Food chain doesn’t involve microbes like bacteria and fungi. It rather starts with herbivores but the flow of energy is towards the smaller organisms, unlike any other food chain.