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Difficulty: HardContinuous and Discontinuous Variation

Match each biological trait or population distribution profile on the left with its correct underlying genetic mechanism or characteristic variation pattern on the right.

  • Human ABO blood group systemMonogenic inheritance resulting in clear-cut qualitative phenotypic categories uninfluenced by environmental factors
  • Human adult height rangePolygenic additive inheritance producing a quantitative continuum of phenotypes significantly modified by nutrition and environment
  • Bell-shaped normal distribution curveGraphical representation of continuous phenotypic variation exhibiting complete graduation between extreme values
  • Discrete bar graph with non-overlapping columnsGraphical representation of discontinuous phenotypic variation showing distinct, isolated phenotypic classes

Answer

Human ABO blood group system matches Monogenic inheritance resulting in clear-cut qualitative phenotypic categories uninfluenced by environmental factors; Human adult height range matches Polygenic additive inheritance producing a quantitative continuum of phenotypes significantly modified by nutrition and environment; Bell-shaped normal distribution curve matches Graphical representation of continuous phenotypic variation exhibiting complete graduation between extreme values; Discrete bar graph with non-overlapping columns matches Graphical representation of discontinuous phenotypic variation showing distinct, isolated phenotypic classes.
Matching each item based on underlying genetic architecture demonstrates that continuous variation is polygenic, environmentally influenced, and bell-curve distributed, whereas discontinuous variation is monogenic, environmentally stable, and represented by discrete categorical bars.

Step-by-Step Solution

1
Analyze the genetic basis of qualitative versus quantitative biological traits.
Discontinuous traits like ABO blood groups show distinct phenotypic classes (monogenic), whereas continuous traits like height span a spectrum of intermediate phenotypes (polygenic).
Single-gene inheritance produces discrete phenotypic groups, while multi-gene additive inheritance produces continuous phenotypic ranges.
2
Evaluate environmental influence on phenotypic variance for each trait type.
ABO blood groups remain constant regardless of environment, whereas adult height is heavily influenced by environmental factors like nutrition during growth.
Continuous traits interact with environmental variables, altering phenotypic outcome, while discontinuous traits are genetically fixed.
3
Associate each variation category with its characteristic graphical representation.
Continuous variation forms a smooth, bell-shaped normal distribution curve; discontinuous variation forms distinct, isolated bars on a histogram.
Smooth transition between phenotypes generates a curve, while clear phenotypic gaps yield separated bars.

Key Concept

Continuous and Discontinuous Variation Mechanisms and Graphical Distributions
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Topics

Continuous and Discontinuous Variation

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