Question

a true -beeding purple flower plants crossed with a true - breeding white flower plant

Answer 1

Interpreting "true‑breeding" as homozygous, and assuming purple is completely dominant to white:

- Let P = allele for purple (dominant), p = allele for white (recessive).
- True‑breeding purple = PP; true‑breeding white = pp.

Cross PP × pp:
- All offspring genotype = Pp.
- All F1 phenotype = purple (because P is dominant).

If you self‑cross the F1 (Pp × Pp), the F2 genotypes and phenotypes are:
- Genotypic ratio: 1 PP : 2 Pp : 1 pp
- Phenotypic ratio: 3 purple : 1 white

(If dominance were incomplete or co‑dominant the results would differ — tell me if that’s the case.)