Question

a purebreeding tall plant with white flowers is crossed with a heterozygous tall, purple plant. what is the probability that you will get a tall, white plant? T=Tall t=Short P=Purple p=white
on a punnet square

Answer 1

Take the parents as:
- Purebreeding tall white = TTpp
- Heterozygous tall, purple = TtPp (heterozygous for both traits)

Gametes:
- TTpp produces only Tp
- TtPp produces TP, Tp, tP, tp (each 1/4)

Punnett-square combos (Tp across left, TP/Tp/tP/tp across top):
- Tp × TP → TTPp (tall, purple)
- Tp × Tp → TTpp (tall, white)
- Tp × tP → TtPp (tall, purple)
- Tp × tp → Ttpp (tall, white)

So 2 out of 4 offspring are tall white → probability = 2/4 = 1/2 = 50%.

(If by “heterozygous tall, purple” you meant heterozygous only for height, e.g. TtPP, then all offspring would be purple and the probability of tall white would be 0%.)