As a result of the dihybrid crossing of two pure pea varieties with yellow smooth seeds and green wrinkled seeds

As a result of the dihybrid crossing of two pure pea varieties with yellow smooth seeds and green wrinkled seeds, four groups of seeds of second generation hybrids differing in appearance were obtained – yellow smooth, yellow wrinkled, green smooth, green wrinkled. Considering that the yellow color and smooth shape of the seeds is dominant and using the law of independent combination of Mendel’s traits, calculate how many yellow smooth seeds were obtained, if it is known that in the remaining groups the number of seeds was distributed as follows: yellow wrinkled – 900, green smooth – 900, green wrinkled – 300.

Yellow seeds – A, green – a.

Smooth seeds – B, wrinkled – b.

Parent genotypes: AABB (smooth yellow), aavb (green wrinkled). Both are digomozygotes, because these are clean lines.

Scheme for solving the problem:

Parents: AABB x aabb,

Gametes: AB x ab,

Offspring: AaBb.

Second cross:

Parents: AaBb x AaBb,

Gametes: AB, Ab, ab, ab x AB, Ab, ab, ab.

With this cross, the phenotype is always approximately 9: 3: 3: 1. Of these, 9 are smooth yellow, 3 smooth green and wrinkled yellow and 1 wrinkled green.

Then: x: 900: 900: 300 = 9: 3: 3: 1.

300 = 1.

X = 9 * 300 = 2700 smooth yellow seeds.