CAIE A-Level Biology A2 17.1.3 Genetic Basis of Variation Questions

Use inheritance information and phenotype evidence to explain how genes, alleles and environmental factors generate variation in Cambridge A Level Biology questions, with…

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Explain how genes, alleles and environmental factors produce variation, using inheritance information and phenotype evidence to support the conclusion.

CAIE A-Level Biology A2 17.1.3 Genetic Basis of Variation Questions question 1

[Maximum number: 2]

The sea blush, Plectritis congesta, is a flowering plant that grows on the west coast of North America.

Individual sea blush plants produce fruit that is either winged or wingless. Investigations have shown that this characteristic is controlled by a single gene with two alleles:
- a dominant winged fruit allele
- a recessive wingless fruit allele.

Fig. 3.1 shows the difference in structure between winged fruit and wingless fruit phenotypes.

Fig. 3.1

Fig. 3.1

Different sea blush plants can have fruit with different colours.

Suggest two ways in which a new fruit colour could naturally occur in a sea blush population.

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