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Difficulty: EasyContinuous and Discontinuous Variation

A biological study recorded a specific phenotypic trait across a large population of organisms. When the collected measurements were plotted on a frequency graph, the data formed a continuous, bell-shaped normal distribution curve. Which of the following traits was most likely being evaluated in this study?

  1. Grain yield per plant in a wheat populationAnswer
  2. B
    ABO blood group classification in humans
  3. C
    Presence or absence of horns in cattle
  4. D
    Human Rhesus factor status

Answer

Grain yield per plant in a wheat population
Traits showing continuous variation, such as grain yield per plant, are polygenic and influenced by environmental conditions. When plotted on a frequency graph across a large population, they generate a smooth, symmetrical bell-shaped curve representing a continuous spectrum of intermediate values.

Step-by-Step Solution

1
Analyze the graphical distribution pattern described in the stem
A smooth, bell-shaped curve indicates a continuous spectrum of phenotypic values across a population.
Continuous variation produces a normal distribution curve because the trait is quantitative, polygenic, and influenced by environmental conditions.
2
Compare the options based on continuous versus discontinuous variation characteristics
Grain yield displays a continuous range of quantitative values, whereas blood groups, horn presence, and Rhesus factor fall into distinct, non-overlapping categories.
Traits under polygenic control show continuous variation, while single-gene traits show discontinuous variation.

Key Concept

Continuous variation involves quantitative traits showing an unbroken spectrum of intermediate phenotypes, producing a bell-shaped normal distribution curve.
Estimated Time:1m 0s
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Topics

Continuous and Discontinuous Variation

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