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Difficulty: HardContinuous and Discontinuous Variation

In human population genetics, traits that display continuous variation—such as adult height and skin color—are characterized by distinct, non-overlapping phenotypic classes because they are governed by polygenic inheritance.

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Answer

The statement is false. Traits showing continuous variation exhibit a continuous spectrum of phenotypic values without distinct categories.
The statement incorrectly combines the genetic cause of continuous variation (polygenic inheritance) with the phenotypic pattern of discontinuous variation (distinct, non-overlapping classes). Traits exhibiting continuous variation present a continuous range of phenotypes without distinct gaps.

Step-by-Step Solution

1
Analyze the trait characteristics described in the statement.
The statement mentions continuous variation traits (adult height and skin color) and claims they produce 'distinct, non-overlapping phenotypic classes'.
Identifying the phenotypic pattern is necessary to evaluate whether it matches continuous or discontinuous variation.
2
Differentiate between continuous and discontinuous phenotypic patterns.
Continuous variation presents an unbroken gradient of intermediate forms with no sharp boundaries. Discontinuous variation presents discrete, clear-cut categories without intermediate phenotypes.
This establishes the correct biological rule regarding phenotypic distribution.
3
Evaluate the underlying genetic mechanisms.
Polygenic inheritance (multiple genes with additive effects combined with environmental factors) generates continuous variation, not discrete classes.
Matching the phenotypic distribution to the underlying mode of inheritance reveals that claiming continuous traits form non-overlapping classes is factually incorrect.

Key Concept

Continuous vs Discontinuous Variation
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Topics

Continuous and Discontinuous Variation

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