Question

Plant height in pea plants is dominant (T). In a wild crop of 8,216 plants, 3,122 are short (tt). How many plants are homozygous dominant? How many are heterozygous and how many are homozygous recessive?

Answer 1

Dominant allele for height T

Recessive allele t

Genotypes for tall Tt or TT

Genotype for short tt.

If there is 8,216 plants, 3,122 are short, which means that 5094 are tall.

Frequency of the recessive homozygous is q2 and it is 3122/8216=0.38, which means that only q=0.62

If p+q=1 (HW equilibrium), than p=0.38

Frequency of dominant homozygous is p2=0.14

The number of dominant homozygous is 0.14*8216=1183

The number of heterozygous is 5094-1183=3911

The number of recessive homozygous is 3122