Section 3: Genetics, Cellular and Molecular Biology
Classical Genetics and Epistasis
Subtopic: Mendelian Genetics & Gene Interactions
Question Statement:
Determine the correctness or otherwise of the following Assertion (a) and the Reason (r)
Assertion:
function.
Cytoplasmic male sterility (cms) is invariably due to defect(s) in mitochondrial
Reason:
cms can be overcome by pollinating a ferility restoring (Rf) plant with pollen
from a non cms plant.
Options:
(A) Typical Mendelian with curved
wings and tan body being dominant
(B) Typical non-Mendelian with curved wings
(C) Mendelian with suppression of
and tan body not following any pattern
phenotypes
(D) Mendelian with single crossover
Official Answer Key:
D
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2010 Q.44)**
**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: *"Determine the correctness or otherwise of the following Assertion (a) and the Reason (r)
Assertion:
function.
Cytoplasmic male sterility (cms) is invariably due to defect(s) in mitochondrial
Reason:
cms can be overcome b..."*
- **Option (D) [CORRECT]**: *"Mendelian with single crossover"*
- Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required.
- **Option (A) [INCORRECT]**: *"Typical Mendelian with curved
wings and tan body being dominant"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (B) [INCORRECT]**: *"Typical non-Mendelian with curved wings"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (C) [INCORRECT]**: *"Mendelian with suppression of
and tan body not following any pattern
phenot"* 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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