Which statement describes a type of variation?
A) Continuous variation is usually caused by the environment only.
B) Continuous variation results in a limited range of phenotypes with no intermediates.
C) Discontinuous variation is usually caused by genes only.
D) Discontinuous variation results in a range of phenotypes between two extremes.
▶️ Answer/Explanation
Ans: C
Discontinuous variation (C) is typically caused by genetic factors alone, resulting in distinct categories (e.g., blood groups) with no intermediates.
Statements A, B, and D are incorrect because:
- A: Continuous variation involves both genes and environment (e.g., height).
- B: Continuous variation shows a range of intermediates.
- D: Discontinuous variation produces discrete categories, not a spectrum.
Thus, only C accurately describes a type of variation.
Which statement about variation is correct?
A) ABO blood groups show continuous variation.
B) Body mass shows discontinuous variation.
C) Seed colour in peas shows continuous variation.
D) Seed shape in peas shows discontinuous variation.
▶️ Answer/Explanation
Ans: D
Discontinuous variation involves distinct categories with no intermediates, while continuous variation shows a range of values.
Option D is correct because pea seed shape (round or wrinkled) is a classic example of discontinuous variation, controlled by a single gene.
The other options are incorrect: A (ABO blood groups are discontinuous), B (body mass is continuous), and C (pea seed color is typically discontinuous, as in Mendel’s experiments).