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CAIE IGCSE Biology 18.1.4 Discontinuous Variation Is Usually Questions

Practise stating that discontinuous variation is usually caused by genes only, while continuous variation is caused by both genes and the environment.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • state that discontinuous variation is usually caused by genes only
  • state that continuous variation is usually caused by both genes and environmental factors

CAIE IGCSE Biology 18.1.4 Discontinuous Variation Is Usually Questions question 1

[Maximum number: 1]

Feather colour in some breeds of chicken is an example of codominance in birds.

In this example, a chicken with white feathers and a chicken with black feathers can breed to produce offspring that have white feathers and black feathers.

The allele for black feathers is FB\mathbf{F}^{\mathbf{B}} and the allele for white feathers is FW\mathbf{F}^{\mathbf{W}}.

Fig. 5.1 is a pedigree diagram of a family of chickens.

Fig. 5.1

Fig. 5.1

State the type of variation that is caused by genes only.

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