A scientist argues that if DNA copying were made perfectly accurate, it would actually be harmful to species in the long run. Do you agree? Justify your answer with reference to the role of variation in species survival.
Generated by claude-sonnet-4-6 · 2026-06-26 01:04 · grounding rag
Model Answer
Yes, I agree with the scientist's argument.
Role of DNA copying accuracy:
DNA copying must be reasonably accurate to maintain body designs that allow organisms to survive in their niche. Consistent copying ensures population stability.
Why perfect accuracy would be harmful:
If DNA copying were made perfectly accurate, no variations would arise in a population. Variations result from small, inevitable errors during DNA copying — these are the source of genetic diversity.
Role of variation in survival:
- Niches can change due to factors like global warming, meteorite hits, or rising water levels — beyond an organism's control.
- If all individuals are identical and the niche changes drastically, the entire population could be wiped out.
- Example: If water temperature rises due to global warming, most bacteria would die, but heat-resistant variants would survive and reproduce.
- Thus, variation ensures that at least some individuals can survive environmental changes.
Conclusion:
Variation is not beneficial to every individual, but it is essential for species survival over time. Perfect DNA copying would eliminate this crucial safety net, making species highly vulnerable to extinction.
Source: Chapter 7, Section 7.1.1 – The Importance of Variation; Section 7.3.1 – Why the Sexual Mode of Reproduction?
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Explanation
What examiners look for (5 marks):
- Clear agreement + reason why perfect accuracy removes variation (1 mark)
- Explanation that variations arise from DNA copying errors (1 mark)
- Why niches change (environmental factors) (1 mark)
- Concrete example — bacteria and heat resistance (1 mark)
- Conclusion: variation helps species, not necessarily every individual (1 mark)
Key points to remember:
- Never say "variation is harmful" — it is harmful to some individuals but beneficial to the species.
- Always use the textbook example (bacteria + global warming) — examiners expect it.
- Keep the distinction clear: consistency of copying = body stability; slight errors = variation = evolutionary advantage.