Final answer:
To calculate the probability of obtaining progeny with genotype TT pp from a cross between Tt Pp and Tt pp plants, a Punnett square is used. The result shows there is a 12.5% chance of getting an offspring with the TT pp genotype.
Step-by-step explanation:
The question posed by the student concerns the genetics of pea plants and the probability of obtaining a specific genotype from a cross between two plants. When a tall, purple flower plant with genotype Tt Pp is crossed with a tall, white flower plant of genotype Tt pp, you can calculate the probability of progeny with TT pp genotype using a Punnett square. To find this probability, we first need to separate each parent's genotype into their respective alleles for height (T and t) and flower color (P and p).
For plant height, the combinations from the first parent (Tt) are T and t, and the second parent (Tt) also provides T and t. For flower color, the combinations from the first parent (Pp) are P and p, while the second parent (pp) can only provide p alleles.
Now, to find the specific genotype TT pp, we are looking for the offspring to receive a T from each parent for height and a p from each parent for flower color. By constructing a Punnett square, the probability of TT pp is the product of the probability of TT for height (which is 1/4) and pp for flower color (which is 1/2). Therefore, the total probability for TT pp offspring is 1/4 times 1/2, which gives us 1/8 or 12.5%.