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1. Mendel crossed together pure breeding pea plants with purple flowers and pure breeding pea plants with white flowers. The offspring plants all had purple flowers.
(a) Explain which phenotype is dominant.

(2)
(b) In a second cross, the purple offspring plants were self-pollinated (pollen from a flower put on the stigma of the same flower).
Suggest how Mendel made sure that all the purple offspring plants were self-pollinated.

(2)
(i) Use a genetic diagram to show the ratio of plants expected by crossing the purple offspring plants in part (b).
Show the parental genotypes and gametes, and the offspring genotypes andphenotypes. Use F and f to represent the alleles.

Parent genotypes

Gametes

Offspring genotypes

Offspring phenotypes

(4)
2. Most simple genetic crosses, such as those studied by Mendel, investigate phenotypes
determined by a pair of alleles, where one allele is dominant over the other allele.
Mendel crossed homozygous tall pea plants with homozygous dwarf pea plants.
All the offspring were tall.
(a) Use a genetic diagram to show the parent genotypes, the gametes formed and
the genotypes of the offspring.

(3)

ii) Give the genotypes of the offspring he obtained from the self-pollinated pea plants.

(1)
Total 12 marks