Question

In a population of pea plants, 36 plants are homozygous for the dominant trait of yellow peas (YY), 48 plants are heterozygous for the yellow pea trait (Yy), and 16 plants have green peas (yy). What is the frequency of the dominant allele (Y) in the population?

A. 0.40
B. 0.55
C. 0.60
D. 0.75

Answer 1

The correct answer would be C. 0.60

It can be calculated with the help of Hardy-Weinberg equation i.e

p² + q² + 2pq = 1

Also, p + q = 1

• where p represents the frequency of dominant allele.

• q represents the frequency of recessive allele.

• p² represents the frequency of homozygous dominant genotype .

• q² represents the frequency of homozygous recessive genotype .

• 2pq represents the frequency of heterozygous genotype.

Number of homozygous dominant (YY) = 36

Number of homozygous recessive (yy) = 16

Number of heterozygous dominant (Yy) = 48

Total number of plants = 100

Now, frequency of homozygous dominant (YY) = 36/100 = 0.36

Therefore, p² = 0.36

So, p = √0.36 = 0.60

Hence, frequency of dominant allele (Y) = 0.60