Question

In the garden pea plant, the gene for flower colour results in purple flowers or white flowers. Two heterozygous purple flowered garden pea plants (Pp) are crossed. Create a Punnett square to determine the genotype and phenotype ratios of the offspring.

Answer 1

Let P = allele for purple (dominant), p = allele for white (recessive). Parents: Pp × Pp. Gametes from each parent: P and p.

Punnett square:

Parent 1 →
P p
Parent 2
P | PP | Pp |
p | Pp | pp |

Genotype outcomes (4 boxes): 1 PP : 2 Pp : 1 pp
- Genotype ratio = 1 : 2 : 1
- Genotype percentages = 25% PP, 50% Pp, 25% pp

Phenotype (purple if PP or Pp, white if pp):
- Phenotype ratio = 3 purple : 1 white
- Phenotype percentages = 75% purple, 25% white