In this question, you are dealing with a dihybrid cross where each parent contributes two alleles for two traits. To determine the expected phenotypic ratio of the offspring, you need to consider how these traits segregate during the process of gamete formation and fertilization.
The dihybrid cross involves alleles for two different traits:
1. Trait 1 with alleles: T (tall) and t (short)
2. Trait 2 with alleles: P (purple) and p (white)
Assuming simple dominance and independent assortment, let's denote the dominant traits by capital letters (T for tall and P for purple) and the recessive traits by lowercase letters (t for short and p for white).
Given Mendelian inheritance rules, we can expect the following:
- Tallness (T) is dominant over shortness (t).
- Purple color (P) is dominant over white color (p).
When you cross two heterozygous parents for both traits (TtPp), the phenotypic ratio in the offspring is determined by the combination of these alleles.
The offspring of such a cross will show a typical Mendelian dihybrid phenotypic ratio of:
- 9 will show both dominant traits (tall and purple),
- 3 will show the first dominant trait and the second recessive trait (tall and white),
- 3 will show the first recessive trait and the second dominant trait (short and purple),
- 1 will show both recessive traits (short and white).
Therefore, the correct phenotypic ratio you would expect to see in the offspring is:
D. 9 tall purple : 3 tall white : 3 short purple : 1 short white
