IB Biology HL 3.2.17 Dihybrid crosses Question Bank
Practise IB Biology HL 3.2.17 by applying dihybrid crosses concepts to exam-style questions.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Exam points
- identify the relevant biological structure, process or evidence
- apply the correct biological mechanism to the question
- evaluate the result using data, adaptation or ecological reasoning
D3.2.17 (HL)—Dihybrid crosses question 1
[Maximum number: 3]
In cats, the allele for curled ears (C) is dominant over the allele for normal ears (c). The allele for black colour (B) is dominant over the allele for grey colour (b). A cross occurs between two cats that are both heterozygous for these unlinked traits.
Using a Punnett grid, predict the ratio of phenotypes of offspring in the next generation.
a. Punnett grid correctly drawn / correct gametes;
b. phenotype ratio 9:3:3:1;
c. correct identification of expected phenotypes (9) black cats with curled ears, (3) grey cats with curled ears, (3) black cats with normal ears, (1) gray cat with normal ears;
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