Match the virus in Group I with the type of genome it contains in Group II.
Group I: P. T4 bacteriophage; Q. SARS-CoV-2; R. Pseudomonas phage φ6; S. φX174 bacteriophage.
Group II: 1. dsRNA; 2. ssDNA; 3. dsDNA; 4. ssRNA.
P-3, Q-4, R-1, S-2
P-2, Q-1, R-4, S-3
P-4, Q-3, R-2, S-1
P-1, Q-4, R-2, S-3
ANSWER
The correct matching is P-3, Q-4, R-1, S-2, which is option (A).
Official answer: ASource: Official answer key, GATE 2023 BT (IIT Kanpur)
T4 bacteriophage is a large tailed phage of with a linear double-stranded DNA genome, so P matches 3 (dsDNA).
SARS-CoV-2 is a coronavirus. Its genome is one positive-sense single-stranded RNA molecule of about 30 kb that acts directly as mRNA, so Q matches 4 (ssRNA).
Pseudomonas phage is an enveloped phage of the family Cystoviridae. Its genome is three segments of double-stranded RNA, so R matches 1 (dsRNA).
is a small icosahedral phage with a circular single-stranded DNA genome of about 5.4 kb, so S matches 2 (ssDNA).
The combination is P-3, Q-4, R-1, S-2, which is option (A).
Option (B) gives T4 ssDNA, which is wrong. Option (C) gives SARS-CoV-2 dsDNA, which is wrong. Option (D) gives T4 dsRNA, which is wrong. Each of these fails on at least one of the facts above.
KEY IDEA
Know the genome type of the standard model viruses. T4 is dsDNA, φX174 is ssDNA, SARS-CoV-2 is ssRNA (positive sense), and φ6 is the classic dsRNA phage with a three-segment genome.
WATCH OUT FOR
Assuming every phage has a DNA genome and overlooking that φ6 is a dsRNA phage. Another slip is mixing up T4 (dsDNA) and φX174 (ssDNA), which are both well-known E. coli phages.
From the GATE 2023 BT paper. Every question of this paper · Download the full paper · All 11 Pathogens & antibiotics questions, with notes
