Subtopic: Discrete & Continuous Probability Distributions
Question Statement:
The standard deviation (o) for the casino payout is Rs.
(rounded off to the
nearest integer).
Options:
(A) Reverse transcriptase
(B) Phospholipase
(C) Phosphatase
(D) ATP synthase
Official Answer Key:
A
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2019 Q.15)**
**1. Governing Concept**:
- **Topic**: Virology & Retroviral Genome Organization
- Human Immunodeficiency Virus (HIV) is a retrovirus (genus *Lentivirus*) with a $(+)$ssRNA genome.
- The viral *pol* gene encodes three essential viral enzymatic activities packaged within the viral capsid:
1. **Reverse Transcriptase (RT)** (RNA-dependent and DNA-dependent DNA polymerase with RNase H activity).
2. **Integrase (IN)** (integrates viral cDNA into host chromosome).
3. **Protease (PR)** (cleaves Gag and Gag-Pol polyproteins into mature functional components).
- Phospholipases, phosphatases, and ATP synthases are cellular enzymes, not encoded by the HIV genome.
**2. Option Analysis**:
- **Option (A) [Reverse transcriptase] is CORRECT**: The signature retroviral polymerase encoded by the viral *pol* gene.
- **Option (B) [Phospholipase] is INCORRECT**: Host lipid-metabolizing enzyme.
- **Option (C) [Phosphatase] is INCORRECT**: Host dephosphorylating enzyme.
- **Option (D) [ATP synthase] is INCORRECT**: Host mitochondrial/plasma membrane enzyme.
**3. Final Answer**:
- **Correct Choice**: **A**
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