In one type of dog, black spots (B) are dominant over brown spots (b) and long tails (L) are dominant over short tails (l). Use the dihybrid cross for parents with the genotypes BBLl and BbLl and determine the likelihood of offspring with the genotype BBLl. BL Bl BL Bl
BL BBLL BBLl BBLL BBLl
Bl BBLl BBll BBLl BBll
bL BbLL BbLl BbLL BbLl
bl BbLl Bbll BbLl Bbll
1/16
2/16
3/16
4/16

the offspring would all be white. if the parents are both white flowers then they have the genotype rr, which when crossed results in an all white punnet square.

we solve the problem using the hardy-wineberg equation.

let us start with the homozygous recessive proportion of individuals with sickle cell anaemia,

we have the proportion as q² = 0.25.

∴ q = 0.5 (frequency of hbs in population)

further,

solving for the frequency of normal cell by using the fact that,

p + q = 1

∴ p = 1 - 0.5 = 1 - 0.5 = 0.5

now we can calculate 2pq in p² + 2pq + q², which is the frequency for heterozygous carriers of sickle cell anaemia,

∴ 2pq = 2 x 0.5 x 0.5 = 0.5

and the homozygous normal cell individuals proportion is given by the expression,

∴ p² = 0.5² = 0.25

hence, the carriers for sickle cell anaemia are in proportion, 0.5, or 50%.