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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?
Explanation
The correct answer is Option 2.
Statement 1 is incorrect because it inaccurately describes the genomic structures of both viruses. Adenoviruses possess double-stranded DNA (dsDNA) genomes, not single-stranded. Conversely, retroviruses (like HIV) contain single-stranded RNA (ssRNA) genomes, which they convert into DNA using the enzyme reverse transcriptase once inside a host cell; they do not have a double-stranded DNA genome in their virion state.
Statement 2 is correct. Adenoviruses are a well-known cause of respiratory infections, including the common cold, sore throats, and bronchitis. AIDS is caused by the Human Immunodeficiency Virus (HIV), which is a classic example of a retrovirus. Since statement 1 is scientifically inaccurate regarding the genetic material and statement 2 correctly identifies the causative agents of the mentioned diseases, only the second statement holds true.
PROVENANCE & STUDY PATTERN
Guest previewThis question is a classic 'Current Affairs disguised as Static Science'. In 2021, the world was discussing Covishield (Adenovirus vector) vs. mRNA vaccines. UPSC pivoted from the vaccine brand names to the fundamental biology of the vectors used. If a major disease/tech is in the news, master its biological basics (Genome type: DNA vs RNA).
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Explicitly states the genome-type comparison between AAV and adenovirus.
- Says adenovirus is double-stranded, which directly contradicts the claim that adenoviruses have single-stranded DNA genomes.
States that viruses are acellular entities that multiply only inside living cells, implying they carry some form of genetic material to direct replication.
A student could combine this with the external fact that different viruses carry either DNA or RNA genomes and then look up whether adenoviruses are DNA or RNA viruses and whether their DNA is single- or double-stranded.
Explains DNA copying as a fundamental biological process and treats DNA as the molecule that stores genetic information in reproducing entities.
Using this general rule, a student can reason that if adenoviruses rely on host machinery to replicate, identifying their nucleic acid type (DNA vs RNA) and structure (single vs double strand) would determine how replication proceeds.
Describes DNA organized into chromosomes in cellular organisms, illustrating that biological genetic material can have defined structural organizations.
A student could use this pattern (genetic material has characteristic structures) and external virology references to compare viral genome organizations (e.g., chromosomes vs viral nucleic acid forms) and thereby investigate adenovirus genome strandness.
This statement analysis shows book citations, web sources and indirect clues. The first statement (S1) is open for preview.
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This statement analysis shows book citations, web sources and indirect clues. The first statement (S1) is open for preview.
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This statement analysis shows book citations, web sources and indirect clues. The first statement (S1) is open for preview.
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