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Difficulty: MediumHuman Morphological and Physiological Variations

Human physiological traits, such as the ability to roll the tongue and the capacity to taste phenylthiocarbamide (PTC), exhibit distinct phenotypic classes with no intermediate forms, classifying them as examples of discontinuous variation.

Answer: Answer

Answer

The statement is TRUE.
Tongue rolling and PTC tasting are classic examples of human physiological variations exhibiting discontinuous variation. They are controlled by major single genes and divide individuals into distinct, qualitative, non-overlapping groups (rollers vs. non-rollers, tasters vs. non-tasters) rather than showing a continuous range of phenotypes.

Step-by-Step Solution

1
Identify the nature of the traits mentioned in the stem.
Tongue rolling ability and PTC tasting are human physiological variations.
Physiological traits relate to the functional capabilities and metabolic responses of an individual.
2
Determine the distribution pattern of these specific physiological traits within human populations.
Individuals are either tongue rollers or non-rollers, and either PTC tasters or non-tasters, with no intermediate phenotype.
Single-gene inheritance produces discrete phenotypic classes unaffected by environmental factors.
3
Evaluate whether discrete phenotypic classification corresponds to discontinuous variation.
Traits divided into clear, non-overlapping categories represent discontinuous variation.
Discontinuous variation is characterized by distinct qualitative phenotypic categories controlled by one or a few genes.

Key Concept

Discontinuous variation in human physiological traits
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Topics

Human Morphological and Physiological Variations

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