Why do cells undergo mitosis? HELP PLEASE
2 answers:
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Answer:
1/2
Explanation:
This question involves a single gene coding for feather color in chickens. The black allele (B) is incompletely dominant over the white allele (W). This means that the allele B will not mask the phenotypic expression of allele W, hence, a third intermediate blue phenotype (BW) will be produced.
According to the question, if two blue chickens are crossed i.e. BW × BW, the gametes B and W will be produced by each parent. Using these gametes in a punnet square (see attached image), the following offsprings will be produced:
BB, BW and WW in the ratio 1:2:1
BB is black, BW is blue, WW is white. Hence, the probability of producing a blue chicken from this cross is 1/2.
Suppose that the proportion of the white crest alleles (r) is given by w and that of the Red crest allele (R) is given by p. We have that p+w=1. The probability that an individual has 2 r alleles is given by w*w since for each allele position the probability is w. Only these individuals have a White phenotype. Hence, we get that w^2=
; the right hand side is the proportion of white birds in the total population. Doing the calculations, this yields that w=0.37. From this, we calculate that p=0.63. The possible ways we have heterozygous individuals are the combinations Rr and rR. The probability for each of those is p*w. Thus, the total probability is 2pw. This is equal to 0.466=0.47. This is the fraction of the future population that is going to be heterozygous assuming the conditions of the Handy-Weinberg equilibrium like random reproductive matching etc.