Subtopic: Fundamentals of Biomolecules, enzyme kinetics
Question Statement:
C-value paradox in evolutionary genomics refers to:
Options:
(A) the lack of correlation between genome size and genetic complexity of an organism
(B) the variation in chromosome count among closely related species
(C) the high mutation frequency observed in non-coding DNA sequences
(D) the relationship between GC content and melting temperature of DNA
Official Answer Key:
A
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2023 Q.15)**
**1. Governing Concept**:
- **Topic**: Evolutionary Genomics & Genome Size Evolution
- The **C-value** is the amount of DNA contained in a haploid nucleus of an organism.
- The **C-value paradox** (or C-value enigma) refers to the observation that eukaryotic genome size (C-value) does not correlate with organismal morphological complexity or evolutionary sophistication (e.g., certain amoebae and lungfishes possess genomes orders of magnitude larger than humans), driven largely by varying proportions of repetitive non-coding DNA.
**2. Option Analysis**:
- **Option (A) [lack of correlation between genome size and organismal complexity] is CORRECT**: The precise scientific definition of the C-value paradox.
- **Option (B) is INCORRECT**: The paradox is not about chromosome number, but absolute DNA quantity.
- **Option (C) is INCORRECT**: Gene density variations are an effect, not the paradox itself.
- **Option (D) is INCORRECT**: Mutation rate variation is not the C-value paradox.
**3. Final Answer**:
- **Correct Choice**: **A**
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