Variation in populations: identify the FALSE statement below regarding continuous and discontinuous variation in genetics and phenotypes.
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AContinuous variation produces a spread of values across a population
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BDiscontinuous variation is largely the result of genetic factors with minimal environmental influence
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CABO blood group is a classic example of discontinuous (qualitative) variation
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DDiscontinuous variation is strongly influenced by environmental conditions
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EContinuous variation is commonly influenced by multiple genes and environment
Answer
Correct Answer: Discontinuous variation is strongly influenced by environmental conditions
Explanation
Introduction / Context:Understanding the distinction between continuous and discontinuous variation is fundamental in genetics and evolutionary biology. Continuous traits (for example, height) show a distribution and are polygenic with environmental effects, while discontinuous traits (for example, ABO blood groups) are qualitative categories, often determined by few genes and relatively insensitive to normal environmental variation.
Given Data / Assumptions:
- Continuous variation: polygenic inheritance plus environment.
- Discontinuous variation: discrete categories with strong genetic control.
- Examples help test conceptual clarity (ABO blood group is discontinuous).
Concept / Approach:Evaluate each statement against these definitions. The false statement will attribute strong environmental influence to a discontinuous trait, which contradicts the expected minimal environmental effect on such categorical phenotypes.
Step-by-Step Solution:
Classify traits: continuous vs. discontinuous.Assess environmental influence: high for continuous, low for discontinuous.Identify the statement mismatching these patterns.Verification / Alternative check:Population genetics texts consistently present blood groups as discrete, genetically determined traits that do not shift with environment.
Why Other Options Are Wrong:
- A/E: Correct descriptions of continuous variation.
- B/C: Correct for discontinuous variation; strong genetic basis, ABO as a discrete example.
- D: False because discontinuous variation is not strongly environment-driven.
Common Pitfalls:Assuming that all traits are equally plastic to environment, or misclassifying polygenic traits as discontinuous.
Final Answer:Discontinuous variation is strongly influenced by environmental conditions