Answer: The frequency of GG is 0.64
Explanation: using Hardy-weinberg equation
g^2 + 2Gg + G^2 =1 ................(1)
And the sum of the alleles at the locus must be 1.
Therefore:
G + g = 1 ..............................(2)
Since
G=0.8
g= 0.2
G^2 =GG (Homozygous G gene)
g^2 = gg (Homozygous g gene)
Using equation 1
GG+ (2×0.8×0.2) + gg =1
Therefore
GG + 0.32 + gg = 1
GG + gg = 0.68...............(3)
Solving equation 2
G + g = 1
g = 1 - G
Square both side
g^2 = (1 - G)^2 ...............4
Where g^2 = gg
Therefore gg = (1 - G)^2.............(5)
Substitute equation 5 into equation 3
GG + (1 - G)^2 = 0.68
Therefore
GG = 0.68 - (1 - G)^2
GG = 0.68 - (1 - 0.8)^2
GG = 0.68 - 0.04
GG = 0.64
