Question

The allele for purple flowers (P) expresses complete dominance over the allele for white flowers (p) in pea plants. In a population of pea plants in Hardy-Weinberg equilibrium, for which p = 0.3, which of the following would be expected in the next generation, if 200 offspring are produced?
1. 134 plants with purple flowers and 66 plants with white flowers
2.140 plants with purple flowers and 60 plants with white flowers
3. 150 plants with purple flowers and 50 plants with white flowers
4. 182 plants with purple flowers and 18 plants with white flowers

Answer 1

Answer:

The correct answer would be 4. 182 plants with purple flowers and 18 plants with white flowers

The Hardy-Weinberg principle states that the genetic diversity (frequencies of the allele and genotypes) of a population remains constant from one generation to the next in absence of any disturbing factors or evolutionary influences.

We assume that the given generations are in Hardy-Weinberg equilibrium. So, the allele and genotype frequencies would remain constant.

The Hardy-Weinberg equations are p² + q² +2pq = 1  and p +q = 1 where,

p represents the frequency of the dominant allele,

q represents the frequency of the recessive allele,

p² represents the individuals with homozygous dominant condition.

q² represents the individuals with homozygous recessive condition.

2pq represents the individuals with heterozygous condition.

Now, the frequency of recessive allele is given as 0.3

So, q = 0.3

Therefore, p would be 0.7 as p + q = 1.

Also, q² = 0.09 = 9%

p² = 0.49 = 49%

2pq = 0.42 = 42%

So, the individuals with homozygous recessive would be = 9% of 200 = 18

The individuals with heterozygous dominant would be = 42% of 200 = 84

The individuals with homozygous dominant  would be = 49% of 200 = 98

Hence, total number of individuals with dominant trait (purple flower) would be 182 and total number of individuals with recessive trait (white flower) would be 18.