Which of the following is true?
1 answer:
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If there are 270 total offspring, we would expect
- 135 curly-winged flies
As flies with one curly allele (Cy) & one normal allele (Cy+) have curly wing, curly wing is dominant to normal wing.
Two curly-winged flies produce 203 curly-winged & 98 normal-winged flies. This is almost in 2:1 ratio for curly wings: normal wings. But expected ratio in offspring when two heterozygous flies are crossed is 3:1.
Only possibility is that homo-zygous for curly gene is lethal, i.e., CyCy genotype is lethal. So, if a curly-winged fly is survived its genotype will be Cy Cy+. Genotype of normal-winged fly will be Cy+ Cy+
<h3>The cross between one curly-winged & one normal-winged fly is shown in below Punnett square.</h3>Gametes Cy+ Cy+
Cy Cy Cy+ (Curly wing) Cy Cy+ (Curly wing)
Cy+ Cy+ Cy+ (Normal wing) Cy+ Cy+ (Normal wing)
We find that expected ratio for curly & normal-winged fly is 1:1. Thus, among 270 offspring we will expect = 135 offspring of curly-winged.
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