UPSC Prelims 2021 · GS Paper I
Question 69: Science and Technology
Consider the following :
- 1.Bacteria
- 2.Fungi
- 3.Virus
Which of the above can be cultured in artificial/synthetic medium?
AnswerUPSC’s answer is (a).
Bacteria and fungi are cellular organisms that can feed and multiply on artificial or synthetic culture media such as nutrient agar. Viruses cannot: they have no metabolism of their own and can multiply only inside living host cells, so they are grown in live cells, embryonated eggs or cell cultures. Remember: viruses need a living host to replicate.
- 1. Bacteria grow on nutrient media such as agar.
- 2. Fungi grow on media such as potato dextrose agar.
- 3. Viruses replicate only inside living host cells.
How you could have got this
- If you were sure statement 3 is not correct, (b), (c) and (d) go: each of them includes 3.
What you needed to know: Viruses replicate only inside living host cells.
Only (a) is left. You didn’t need statements 1 or 2.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Right: bacteria and fungi grow on synthetic media.
- (b) Wrong: viruses cannot be cultured on artificial media.
- (c) Wrong: viruses cannot, and it omits fungi.
- (d) Wrong: viruses need living host cells.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2021, General Studies Paper I, Series A. The paper on upsc.gov.in.