0654.B16.3.11 — Use genetic diagrams to predict the results of monohybrid crosses and calculate phenotypic ratios, limited to 1 : 1 and 3 : 1 ratios: past paper questions
Real questions on 0654.b16.3.11 — use genetic diagrams to predict the results of monohybrid crosses and calculate phenotypic ratios, limited to 1 : 1 and 3 : 1 ratios
The newest 8 of 8 written questions. Open one to see it on the real paper.
- 0654/32 · October/November 2025 · Q3b(ii)[2]
Cystic fibrosis is caused by a recessive allele, f. Two people that do not have cystic fibrosis have a child with cystic fibrosis. Complete the Punnett square to show why the child has cystic fibrosis. mother’s genotype father’s genotype F f
See it on the paper → - 0654/32 · May/June 2025 · Q2c(i)[2]
Table 2.1 shows the different possible combinations of alleles, a description of the combination and the colour of the pea seeds. Complete Table 2.1. Table 2.1 combination of alleles Yy description of combination colour of pea seeds homozygous dominant yellow yellow
See it on the paper → - 0654/32 · May/June 2025 · Q2c(ii)[2]
The scientist uses plants with yellow pea seeds to produce plants with green pea seeds. Complete the Punnett square in Fig. 2.2 to show how plants with yellow pea seeds produce plants with green pea seeds. parental gametes 1 parental gametes 2 Y y
See it on the paper → - 0654/32 · May/June 2025 · Q2c(iii)[1]
State the expected ratio of seed colours from this cross. yellow pea seeds : green pea seeds
See it on the paper → - 0654/33 · May/June 2025 · Q2c(i)[2]
Table 2.1 shows the different possible combinations of alleles, a description of the combination and the colour of the pea seeds. Complete Table 2.1. Table 2.1 combination of alleles Yy description of combination colour of pea seeds homozygous dominant yellow yellow
See it on the paper → - 0654/33 · May/June 2025 · Q2c(ii)[2]
The scientist uses plants with yellow pea seeds to produce plants with green pea seeds. Complete the Punnett square in Fig. 2.2 to show how plants with yellow pea seeds produce plants with green pea seeds. parental gametes 1 parental gametes 2 Y y
See it on the paper → - 0654/33 · May/June 2025 · Q2c(iii)[1]
State the expected ratio of seed colours from this cross. yellow pea seeds : green pea seeds
See it on the paper → - 0654/22 · May/June 2021 · Q11[1]
Which row is correct for this cross?
See it on the paper →
What examiners said
The writing of the homozygous genotype was generally well done. However, many candidates repeated homozygous dominant for the description of Yy.
— Examiner report, May/June 2025, 0654/32 Q2(c)(i) (Cambridge)
There were a significant number of very clear, well-presented answers given. Others were evidently not familiar with the use of a Punnet square. This was shown by the use of phenotypes or genotypes instead of alleles in the gametes.
— Examiner report, May/June 2025, 0654/32 Q2(c)(ii) (Cambridge)
Most candidates tried to use their Punnet square to answer this question. Common mistakes were to state that the Yy genotype would give green peas or to add up the number of Y and y alleles and give this as the ratio rather than the phenotypes.
— Examiner report, May/June 2025, 0654/32 Q2(c)(iii) (Cambridge)
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