2006midterm1Bkey

2006midterm1Bkey - BICD100 Midterm 1 (1/30/06) KEY TO...

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1 BICD100 Midterm 1 (1/30/06) KEY TO VERSION B 1. A pet store owner wants to breed some attractive new varieties of tropical fish. In a particular species of fish, she determines that the difference between electric blue vs. black body color is due to alleles of a single gene (B), with black dominant to blue. She also determines that the presence of a yellow spot on the fish’s side is determined by another gene (Y), with spotted being recessive to unspotted. Finally, she determines that the difference between large tails and small tails is due to a third gene (T) with large tails dominant to small tails. Genes controlling all three traits are on different chromosomes. a. A spotted black fish with a large tail was crossed to an unspotted blue fish with a small tail. Among 20 F 1 progeny fish, about half were blue and half were black, half had spots and half didn’t, and all had large tails. Using upper and lower case letters to indicate dominant and recessive alleles of the B, Y and T genes, what were the genotypes of the parents (8 pts)? Parental genotypes were Bb yy TT and bb Yy tt b. Among the progeny of the cross described in part a, the pet store owner particularly likes the spotted blue fish with large tails, and wants to produce more of these fish for sale in her store. To accomplish this, she crosses two spotted, blue, large tailed F 1 progeny together. What proportion of the F 2 will be spotted and blue with large tails like their parents (6 pts)? Spotted, blue, large-tailed F 1 progeny are bb yy Tt When two of these are crossed together, 3/4 of progeny are spotted and blue with large tails (either bb yy TT or bb yy Tt)
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2 2. Circle each of the following that are possible modes of inheritance for the rare trait represented in
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2006midterm1Bkey - BICD100 Midterm 1 (1/30/06) KEY TO...

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