In a population of organisms occupying a stable niche, which of the following best explains why some variation among individuals is still beneficial?
(A) Variation allows natural selection to favour faster-reproducing individuals, stabilising the population size.
(B) Variation ensures that if the niche changes unexpectedly, at least some individuals may survive the new conditions.
(C) Variation reduces the frequency of DNA copying errors in subsequent generations.
(D) Variation enables every individual to adapt to multiple niches simultaneously, increasing overall survival.
Generated by claude-sonnet-4-6 · 2026-06-26 01:04 · grounding rag
Model Answer
(B) Variation ensures that if the niche changes unexpectedly, at least some individuals may survive.
If a niche is drastically altered, most organisms die, but individuals with favourable variations survive and grow further, ensuring species survival.
Source: Chapter 7, Section 7.1.1 – The Importance of Variation
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Explanation
The passage directly states that if variations are present in a few individuals and the niche changes drastically, those variants have a chance to survive. Option B mirrors this exactly.
- (A) is wrong — variation is not about faster reproduction within a stable niche.
- (C) is wrong — variation actually results from DNA copying errors, it does not reduce them.
- (D) is wrong — individuals do not adapt to multiple niches simultaneously; that contradicts the niche concept.
Key phrase to remember: "Variation is useful for the survival of species over time."