Question

Which of the following statements is true about Retroviridae?

A. SS RNA
B. Diploid genome
C. RNA dependent RNA polymerase
D. Both horizontal and vertical transmission

Choose the correct answer from the options given below.

• A. A, B and D only
• B. B and C only
• C. B, C and D only
• D. D only

Hint:

Remember the distinguishing feature of Retroviridae: it contains a diploid ssRNA genome and the enzyme reverse transcriptase (RNA-dependent DNA polymerase), not RNA-dependent RNA polymerase.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Retroviridae is a family of enveloped viruses that contains positive-sense single-stranded RNA as its genetic material.
These viruses are unique because they convert their RNA genome into DNA using the enzyme reverse transcriptase before integrating into the host genome.
Detailed Explanation:
Evaluate each statement individually.
Statement A: SS RNA
Retroviruses possess two identical copies of positive-sense single-stranded RNA.
Therefore, Statement A is true.
Statement B: Diploid genome
Unlike most RNA viruses, Retroviridae contains two copies of its RNA genome inside each virion.
Hence, it is described as having a diploid genome.
Therefore, Statement B is true.
Statement C: RNA dependent RNA polymerase
Retroviruses do not possess RNA-dependent RNA polymerase.
Instead, they contain RNA-dependent DNA polymerase, commonly known as reverse transcriptase.
Thus, Statement C is false.
Statement D: Both horizontal and vertical transmission
Retroviruses may spread horizontally through body fluids and vertically from mother to offspring.
Therefore, Statement D is true.

Step 2: Final Answer:
True statements are A, B and D only.
\[ \boxed{(A) A, B and D only \]