Q. Consider the following statements : - Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
- Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus.
Which of the statements given above is/are correct? (UPSC Prelims 2021)
Answer:
2 only
Notes: The correct answer is
[B] 2 only. This question distinguishes between the genetic structures and the diseases associated with different classes of viruses.
- Statement 1 (Incorrect): This statement incorrectly describes the genomic structure of both viruses.
- Adenoviruses actually have double-stranded DNA (dsDNA) genomes. They are non-enveloped viruses known for causing respiratory, gastrointestinal, and eye infections.
- Retroviruses (like HIV) have single-stranded RNA (ssRNA) genomes, not DNA. They are unique because they use an enzyme called reverse transcriptase to convert their RNA into DNA once they enter a host cell.
- Statement 2 (Correct): This accurately identifies the causative agents for these common conditions.
- Common Cold: While Rhinoviruses are the most frequent cause, Adenoviruses are a well-known cause of "cold-like" symptoms, sore throats, and bronchitis.
- AIDS: It is caused by the Human Immunodeficiency Virus (HIV), which is a classic example of a Retrovirus.