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Difficulty: EasyContinuous and Discontinuous Variation

In a genetic study of human physical traits, researchers observed that certain characteristics show distinct, non-overlapping categories with no intermediate forms. Which of the following traits demonstrates this pattern of variation?

  1. Ability to roll the tongueAnswer
  2. B
    Body height in adults
  3. C
    Total body weight
  4. D
    Skin pigmentation tone

Answer

Ability to roll the tongue
The ability to roll the tongue is an example of discontinuous variation because it presents clear, discrete phenotypic categories with no intermediate phenotypes, controlled primarily by simple monogenic inheritance.

Step-by-Step Solution

1
Define discontinuous variation
Discontinuous variation refers to qualitative traits controlled by one or a few major genes that exhibit clear-cut, non-overlapping phenotypic categories without intermediate forms.
Understanding the definition helps distinguish discontinuous traits from continuous traits.
2
Evaluate the given traits against the definition
Ability to roll the tongue falls into distinct categories (individuals can either roll their tongue or cannot), whereas height, weight, and skin pigmentation exhibit a continuous range of intermediate phenotypes.
Classifying each option based on whether intermediate forms exist identifies the correct discontinuous trait.

Key Concept

Discontinuous Variation Traits
Estimated Time:45s
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Topics

Continuous and Discontinuous Variation

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