Which one of the following statements explains higher mutation rate and faster evolution found in RNA virus?
- A.RNA is relatively unstable compared to DNA.
- B.Virus can multiply only within the living cell of a host.
- C.Metabolic processes are absent in virus.
- D.Virus can remain latent for a long period.
Correct answer
Explanation
The correct answer is A, RNA is relatively unstable compared to DNA. RNA is usually single-stranded and its sugar, ribose, carries an extra hydroxyl group, which makes the molecule more reactive and easier to break or alter than double-stranded DNA. RNA viruses also copy their genes with an enzyme, RNA-dependent RNA polymerase, that has little or no proofreading ability, so copying errors are not corrected. The result is a very high mutation rate, which lets RNA viruses change quickly and escape immunity and drugs. This is why influenza vaccines are updated every season and why new variants of the coronavirus kept appearing. HIV, hepatitis C, dengue and measles are other RNA viruses. Option B is wrong because all viruses, DNA or RNA, multiply only inside living cells, so it cannot explain a difference. Option C is wrong because no virus has its own metabolism. Option D is wrong because latency slows change rather than speeding it up. Exam tip: unstable RNA plus no proofreading means fast mutation, as in flu, HIV and coronavirus.
Practice Questions
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- B.nose
- C.ear
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