Q1. [2] medium thorough-understanding
In an asexually reproducing bacterial population, trait A is present in 10% of individuals and trait B is present in 60% of individuals. Which trait most likely arose earlier, and why?
Generated by claude-sonnet-4-6 · 2026-06-26 01:02 · grounding rag
Model Answer
Trait B (present in 60%) most likely arose earlier.
In an asexually reproducing population, variations arise due to minor inaccuracies in DNA copying over successive generations. A trait that appeared earlier would have had more generations to be inherited and passed on, thus accumulating in a greater proportion of the population over time.
Source: Chapter 8, Section 8.1 – Accumulation of Variation During Reproduction
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Explanation
- The key logic: older variation = more time to accumulate = higher frequency in the population.
- The textbook question (Q1 under Section 8.1) directly asks this — examiners expect you to link frequency of a trait to how long it has been present.
- Avoid over-explaining; just state which trait, then give the one-line reason about inheritance over generations.
- Don't confuse this with dominance/recessiveness — that applies to sexual reproduction, not this concept.