Statement I :
Genetic code is degenerate.

Statement II :
Genetic code resists single-base substitution mutations.

In the light of the above statements, choose the
correct answer from the options given below :

1. Both Statement I and Statement II are true
2. Both Statement I and Statement II are false
3. Statement I is true but Statement II is false
4. Statement I is false but Statement II is true

   Statement I is true, but Statement II is false. The correct option is Statement I is true but Statement II is false.

   Genetic Code Degeneracy

   The genetic code is degenerate because most amino acids are encoded by multiple codons (typically 2–6), mainly differing at the third (“wobble”) position. For example, leucine is coded by six codons (UUA, UUG, CUU, CUC, CUA, CUG). This redundancy arises from 64 codons (4³ combinations) specifying only 20 amino acids plus 3 stop signals.

   Mutation Resistance

   The genetic code does not inherently resist single-base substitution mutations. Such mutations (e.g., point mutations) can change a codon to one for a different amino acid (missense), create a premature stop (nonsense), or rarely cause no change (silent, due to degeneracy). Degeneracy buffers some mutations (e.g., third-position changes often remain synonymous), but it does not “resist” them—the code tolerates rather than prevents effects.

   Option Analysis

   • Both true: Incorrect. Statement I holds, but II does not—degeneracy reduces mutation impact selectively, not broadly resists substitutions.

   • Both false: Incorrect. Statement I is a core property of the code.

   • I true, II false: Correct. Matches above: degeneracy exists, but no resistance to single-base changes.

   • I false, II true: Incorrect. I is true; II misstates code function.

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   The genetic code degenerate nature is a foundational concept in molecular biology, often tested in exams like GATE Life Sciences. This article breaks down Q.39 on genetic code is degenerate (Statement I) and whether it resists single-base substitution mutations (Statement II), explaining every option with evidence.

   What Does “Genetic Code is Degenerate” Mean?

   Genetic code degenerate refers to multiple codons encoding the same amino acid. With 64 codons for 20 amino acids, redundancy occurs—e.g., arginine via CGU, CGC, CGA, CGG, AGA, AGG. This third-position wobble minimizes mutation effects but evolved via ribosomal mechanisms.

   Key Point: Statement I is true—a universal trait confirmed across organisms.

   Does Genetic Code Resist Single-Base Substitution Mutations?

   No. Single-base substitution mutations (point mutations) alter one nucleotide, potentially causing:

   • Silent: No amino acid change (degeneracy helps here).

   • Missense: Different amino acid.

   • Nonsense: Premature stop.

   The code tolerates some via degeneracy but does not “resist” (prevent or block) mutations. UV light or chemicals induce them regardless.

   Key Point: Statement II is false—degeneracy mitigates impact, not resistance.

   Correct Answer: Statement I True, Statement II False

   This matches option 3. Degeneracy provides robustness, but mutations occur and propagate without special resistance.

   Option	Why Correct/Incorrect
   Both true	Wrong: II false—no broad resistance.
   Both false	Wrong: I defines degeneracy.
   I true, II false	Correct: Aligns with codon table properties.
   I false, II true	Wrong: I true, II false.

   Why Degeneracy Evolved

   Ribosomal residue A1493 stabilizes second codon positions, enabling degeneracy early in evolution. It reduces error costs without halting mutations.

   Ideal for genetic code degenerate exam prep—search “genetic code resists mutations” for similar questions.