Question

In peas, the trait for tall plants is dominant (T) and the trait for short plants is recessive (t). The trait for yellow seeds is dominant (Y) and the trait for green seeds is recessive (y). A cross between two plants results in 292 tall yellow plants and 103 short green plants. Which of the following are most likely to be the genotypes of the parents?
- TyYY x Ttyy
- TTYy x TTYy
- TTyy x TTYy
- TtYy x TtYy

Answer 1

Answer:

The correct answer is option-  TtYy x TtYy.

Explanation:

In this dihybrid cross the pea plant have dominant alleles are tall - T and yellow - Y while the recessive alleles are Short - t and green - y. The dominant traits masks the plants recessive character if present together.

To get offspring with tall and green plants should have at least one allele of T and Y and for the short green they must have sets of alleles ttyy in both. In the given option the first option one of the parent lack one of the character of size of pea plant. In the second option and third option there is no allele for short plants.

Thus, the correct answer is - TtYy x TtYy

Answer 2

Answer:

Option D, TtYy x TtYy

Explanation:

Given

Tall plant trait (T) is dominant over short plant trait (t)

Trait for yellow seeds (Y) is dominant over traits for green seeds (y)

Total of $292$ plants are tall & yellow while $103$ plants are short and green

Thus, % of plants short and green is equal to

$\frac{103}{103+292} * 100\\\\26$%

Nearly one fourth of the plants are having homologous recessive trait

Thus, the possible genotype of parent would be TtYy x TtYy as only in this the homologous recessive alleles can pair up.

Option D is correct