NEET 2023 Botany Mutation Assertion Reason Question

To analyze the given statements and determine the correct answer, let’s break down each statement regarding RNA and its mutation rates.

Statement I: RNA mutates at a faster rate.

This statement is true. RNA viruses generally have higher mutation rates compared to DNA organisms. The primary reason for this increased mutation rate is the lack of proofreading mechanisms in RNA-dependent RNA polymerases. While DNA replication involves enzymes that can correct errors (like DNA polymerases with proofreading activity), RNA viruses often rely on their polymerases, which do not have such error-correcting capabilities. Consequently, the replication of RNA genomes leads to a higher frequency of mutations.

Statement II: Viruses having RNA genome and shorter life span mutate and evolve faster.

This statement is also true. RNA viruses tend to have shorter generation times, which means they can replicate rapidly. A shorter lifespan allows these viruses to go through more replication cycles in a given time frame. Each replication cycle is an opportunity for mutations to occur. Therefore, the combination of a high mutation rate (due to the RNA genome) and a fast replication cycle (due to a shorter lifespan) means that RNA viruses can evolve quickly. This rapid evolution enables them to adapt to changing environments, evade host immune responses, and develop resistance to antiviral therapies.

Conclusion on the Correct Answer

Since both statements are true, the correct answer is D) Both Statement I and Statement II are true.

Clarification of Incorrect Options

• Option A: Both Statement I and Statement II are false.

  • This option is incorrect because, as explained, both statements are true.

• Option B: Statement I is true but Statement II is false.

  • This option is incorrect because Statement II is also true.

• Option C: Statement I is false but Statement II is true.

  • This option is incorrect because Statement I is true.

Summary

In summary, both statements reflect the characteristics of RNA viruses accurately:

1. RNA has a higher mutation rate due to the absence of proofreading mechanisms.
2. RNA viruses with shorter lifespans replicate quickly, leading to rapid evolution.

Thus, the answer is D, confirming the validity of both statements.

This understanding is fundamental in the study of viral evolution and the implications for public health, especially concerning emerging infectious diseases.