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Difficulty: HardHuman Morphological and Physiological Variations

Human physiological traits such as blood pressure and resting pulse rate exhibit discontinuous variation because individuals strictly belong to distinct, non-overlapping phenotypic categories controlled solely by single-gene inheritance.

Answer: Answer

Answer

False
The statement is false because blood pressure and resting pulse rate exhibit continuous physiological variation, characterized by a smooth quantitative gradient across a population under polygenic control and environmental modification.

Step-by-Step Solution

1
Analyze the pattern of variation exhibited by physiological traits like blood pressure and resting pulse rate.
Blood pressure and pulse rate display a continuous spectrum of phenotypic values across a population spectrum without distinct breaks.
Continuous variation presents a gradual quantitative range of phenotypic expressions rather than distinct categories.
2
Examine the underlying genetic basis and environmental interaction for these physiological traits.
These traits are polygenic (controlled by multiple genes working additively) and are substantially modified by environmental factors.
Polygenic inheritance combined with environmental modifications produces a smooth, bell-shaped normal distribution curve.
3
Contrast continuous physiological traits with discontinuous variations.
Discontinuous variations (such as ABO blood groups or tongue rolling) consist of clear-cut non-overlapping phenotypic categories controlled by single genes and are generally unaffected by environmental conditions.
Mislabelling continuous physiological traits as discontinuous fails to account for polygenic control and environmental susceptibility.

Key Concept

Continuous vs. Discontinuous Variation in Human Physiological Traits
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Topics

Human Morphological and Physiological Variations

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