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Please help!Multiple choice question on inheritance patterns

Thu Dec 31, 2009 8:24 pm

A mutation affecting the eye, called Bar, does not affect color. Instead, it affects the shape of the eye, changing it from the normal, round phenotype (aka "wild type") to an elongated, oval shape (aka "Bar"). Wild type flies were crossed with Bar eyed flies. half of the F1 progeny had Bar shaped eyes, and the other half had wild type eyes. When the wild type F1 flies were crossed with the Bar eyed F1 flies, the F2 generation showed the same phenotype as the F1 generation: half were wild type, and half had Bar eyes.

Q1. The inheritance patter of Bar eyes fits with which of the following mechanism?
A. autosomal recessive
B. autosomal dominant.
c. sex-linked recessive
D. sex-linkded dominant

Q2. What is the best way to describe the genotype of the Bar eyed mutants in the parental generation in Cross 4:
A. homozygous dominant
B. homozygous recessive
C. Heterozygous
D. Hemizygous

I personally think that the answer is A and C for Q1 and Q2, respectively.

What do you think?

Re: Please help!Multiple choice question on inheritance patt

Wed Jan 01, 2014 3:41 pm

"Bar eyes" in Drosophila in real life are supposed to be sex-linked dominant, so that would be choice (D) in the first question. And if I understand the next part correctly, sex-linked dominant is consistent with the ratios in the pedigrees