Prelims 2013 · archive
EasyWith reference to the food chains in ecosystems, which of the following kinds of organism is/are known as decomposer organism/organisms?
- 1.Virus
- 2.Fungi
- 3.Bacteria
Select the correct answer using the codes given below:
Answer & explanation
Answer: (b) 2 and 3 only
Decomposers are organisms that feed on dead organic matter and break it down. In ecosystems these are mainly fungi and bacteria. Viruses cannot feed on dead matter. They multiply only inside living host cells, so they are not decomposers.
- ✗ 1. Viruses do not break down dead organic matter for energy. They replicate only by taking over a living host cell, so they have no role as decomposers in a food chain.
- ✓ 2. Fungi are among the main decomposers. They live on dead organic matter (detritus) and digest it, which makes them saprotrophs.
- ✓ 3. Bacteria are the other main decomposers. They break down dead matter and return nutrients to the soil and water.
Remember · Decomposers (saprotrophs) are mainly fungi and bacteria. They make up the detritus food chain, which begins with dead organic matter. Viruses are not decomposers, because they replicate only inside living host cells.
📘 Read it in NCERT: Class 12 Biology, Ch 12 (practise this chapter) · Class 12 Biology, Ch 7 (practise this chapter)
Sources
- NCERT Class 12 · Biology, Chapter 12 “It is made up of decomposers which are heterotrophic organisms, mainly fungi and bacteria. They meet their energy and nutrient requirements by degrading dead organic matter or detritus.”
- NCERT Class 12 · Biology, Chapter 7 “This viral DNA gets incorporated into host cell's DNA and directs the infected cells to produce virus particles”
Question: UPSC Civil Services (Preliminary) 2013, General Studies paper. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). ·