Question

This scenario covers questions 5 – 7. Chad is doing a project for science class. He is trying to determine the inheritance pattern of flower color in pea plants. He has crossed true breeding purple flowered pea plants (PP) with true breeding white flowered pea plants (pp) and found that the entire first generation (known as the F1 generation) was purple. Next, he self-crossed the F1 generation. He found that the next generation (known as the F2 generation) had 73 plants with purple flowers and 27 plants with white flowers. How could Chad determine the genotype of the purple flowered pea plants in the F2 generation

Answer 1

Answer:

Out of four offspring in second generation , 3 are purple color with frequency of 0.23 homozygous purple color flower and 0.25 heterozygous purple color flower

Explanation:

Given ,

Allele for purple color flower is "P"

Allele for white color flower is "p"

Genotype of true breeding purple flower is "PP"

Genotype of true breeding white flower is "pp"

F1 Generation -

PP x pp

Pp, Pp, Pp, Pp

All are purple in color, thus purple color  is dominant over white color

F2 generation -

Pp x Pp

PP, Pp, Pp, pp

Given 27 plants are white in color, thus frequency of white recessive flower is

$\frac{27}{27+73} \\\frac{27}{100} \\= 0.27\\p^2 = 0.27\\p = 0.519 = 0.52$

p is the frequency for purple color allele

q is the frequency for white color allele

$q = 1-0.52\\q = 0.48$

$q^{2}$ represent the frequency of homozygous purple flower

$q^2 = 0.48^2 \\q^2 = 0.23$

$p^2+ q^2 + 2pq = 1\\2pq = 1 - 0.52 -0.23\\2pq = 0.25$