Consider the following statements:
- 1.Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
- 2.Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus.
Which of the statements given above is/are correct?
Answer & explanation
Answer: (b) 2 only
Statement 2 is correct: adenoviruses can cause cold-like illness, and AIDS is caused by HIV, which is a retrovirus. Statement 1 is wrong on both counts, because adenoviruses have double-stranded DNA genomes, while retroviruses carry an RNA genome.
- ✗ 1. Adenoviruses are non-enveloped viruses with double-stranded DNA, not single-stranded DNA. Retroviruses, such as HIV, have an RNA genome (later copied into DNA inside the host cell), not a double-stranded DNA genome.
- ✓ 2. Adenoviruses cause respiratory infections, including mild cold-like illness. AIDS is caused by the Human Immunodeficiency Virus (HIV), a retrovirus.
Remember · Adenovirus: double-stranded DNA, respiratory infections. Retrovirus (HIV, cause of AIDS): RNA genome.
📘 Read it in NCERT: Class 12 Biology, Ch 7 (practise this chapter)
Sources
- NCERT Class 12 · Biology, Chapter 7 “AIDS is caused by the Human Immuno deficiency Virus (HIV), a member of a group of viruses called retrovirus, which have an envelope enclosing the RNA genome”
- Gu et al., Molecular characterization of human adenovirus type 55, Virus Genes (2025), PubMed Central (US National Library of Medicine) ↗ “Adenoviruses are non-enveloped, double-stranded deoxyribonucleic acid (DNA) viruses that belong to the family Adenoviridae.”
- CDC, About Adenovirus (archived copy) ↗ “Adenoviruses are common and typically cause mild cold or flu-like symptoms.”
Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·