Consider the fly crosses presented in the attached file. Here we have a female f
ID: 277700 • Letter: C
Question
Consider the fly crosses presented in the attached file. Here we have a female fly with purple eyes (mutant) crossed with a male fly with red eyes (wild-type). Both are true-breeding. If the autosomal gene coding for eye color has two alleles, labeled:
M = Mutant allele,
W = Wild-type allele,
we may determine the phenotypes and counts of the F1 offspring and F2 offspring produced by an F1-intercross mating (using the Fly Lab software).
What values would you use for the expected counts of the Red-eyed flies and the Purple-eyed flies in a Chi-square goodness of fit test, where the observed data are the F2 phenotype counts (all counts are rounded to nearest integer)?
A.
Male flies with red eyes: 128;
Female flies with red eyes: 128;
Male flies with purple eyes: 384;
Female flies with purple eyes: 384.
B.
Male flies with red eyes: 384;
Female flies with red eyes: 384;
Male flies with purple eyes: 128;
Female flies with purple eyes: 128.
C.
Male flies with red eyes: 375;
Female flies with red eyes: 375;
Male flies with purple eyes: 125;
Female flies with purple eyes: 125.
D.
Male flies with red eyes: 125;
Female flies with red eyes: 125;
Male flies with purple eyes: 375;
Female flies with purple eyes: 375.
E.
Male flies with red eyes: 250;
Female flies with red eyes: 250;
Male flies with purple eyes: 250;
Female flies with purple eyes: 250.
Explanation / Answer
Here, the answer is A.
Male flies with red eye 128
Female flied with red eye 128
Male flies with purple eye 384
Female flies with purple eye 384
When we cross purple ( mutant ) female with wild type male F1 offspring produce. When F1 offspring intercross then F2 offspring produce in which 50% offspring contain red eye and 50% contain purple eye. This cross follow ratio 1:3 means 1 part of wild type and 3 part of purple eyes because female contain mutant gene and male contain wild type. Here, F1 offspring become mutant and when mutant crossed with each other it produce F2 offspring.
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