Subtopic: Discrete & Continuous Probability Distributions
Question Statement:
What will be the probability of having the colour-blind son to a woman with phenotypically
has no previous children)
normal parents and a colour-blind brother, and married to a normal man? (Assume that she
Options:
(A) 100 %
(B) 50 %
(C) 25 %
(D) 12.5 %
Official Answer Key:
D
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2011 Q.48)**
**1. Governing Concept & Syllabus Classification**:
- **Section**: Biotechnology
- **Question Type**: **MCQ** (2 Marks)
- **Core Topic**: Biochemistry, Microbiology & Molecular Biology
**2. Detailed Step-by-Step Analytical & Scientific Derivation**:
- **Systematic Conceptual & Option-by-Option Evaluation**:
- Problem Focus: *"What will be the probability of having the colour-blind son to a woman with phenotypically
has no previous children)
normal parents and a colour-blind brother, and married to a normal man? (Assume that she..."*
- **Option (D) [CORRECT]**: *"12.5 %"*
- Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required.
- **Option (A) [INCORRECT]**: *"100 %"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (B) [INCORRECT]**: *"50 %"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (C) [INCORRECT]**: *"25 %"* does not satisfy the precise boundary conditions or molecular specificity.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **D**
- **Scoring Criteria**: 2 Marks (Negative marking: -0.66 marks).
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