Edexcel IGCSEBiologyGeneral Applications6 Marks
In pea plants, tall (T) is dominant to dwarf (t), and purple flowers (P) are dominant to white flowers (p). A pure-breeding tall pea plant with purple flowers is crossed with a pure-breeding dwarf pea plant with white flowers.
- (a)State the genotypes of the two parent plants.[2]
- (b)Determine the genotype and phenotype of the F1 generation.[2]
- (c)If two F1 generation plants are crossed, what would be the expected phenotype ratio in the F2 generation for height?[2]
Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- M1 for Tall purple parent: TTPP.
- A1 for Dwarf white parent: ttpp.
- M1 for Genotype: TtPp.
- A1 for Phenotype: Tall with purple flowers.
- M1 for Punnett square / genetic cross showing Tt x Tt results in TT, Tt, Tt, tt.
- A1 for 3 Tall : 1 Dwarf.
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