Exam 3 Short answers ##

Exam 3 Short answers ## - 31 In parakeets two autosomal...

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31. In parakeets, two autosomal genes that are located on different chromosomes control the production of feather pigment. Gene B codes for an enzyme that is required for the synthesis of a blue pigment, and gene Y codes for an enzyme required for the synthesis of a yellow pigment. Recessive, loss-of-function mutations resulting in no production of the affected pigment are known for both genes. A parakeet breeder has two green parakeets and mates them. Among the many offspring are birds that are green, blue, yellow, and albino (no pigmentation). a) Based on these observations, what are the genotypes of the green parents? (2) BbYy for both b) Give the possible genotype(s) for each color of offspring and indicate what fraction of the total progeny should exhibit each color form. (4) BBYY, BbYy, BBYy, or BbYY- green 9/16 BByy or Bbyy – blue 3/16 bbYY or bbYy – yellow 3/16 bbyy – albino 1/16 0.5 points for each correct genotype-phenotype match and correct fraction. c) If the parents were the progeny of a cross between birds from two true-breeding lines, what two types of crosses between the true-breeding lines could have produced the green parents? Indicate both genotypes and phenotypes for each cross. (4) BByy X bbYY (blue X yellow) and BBYY X bbyy (green X albino) 1 pt. for each correct genotype & phenotype for the 2 crosses.
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32. Charles Darwin and Alfred Russel Wallace (shown above in later life) developed the theory of evolution by natural selection based on similar specific observations and logical deductions. The following questions relate to some of these observations and logical deductions. a) Darwin and Wallace were both well-travelled. What fundamental observation did both scientists make regarding individuals in natural populations? (2). Individuals in populations vary in traits that are heritable. b) The economist, Thomas Malthus, influenced Darwin and Wallace with what observation about human populations that they then generalized to other species? (2) More offspring are produced than can survive to reproduce, leading to a competition for resources (the struggle for existence). c) Explain how the knowledge of the breeding of domesticated plant and animal species
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This note was uploaded on 01/16/2012 for the course BIO 171 taught by Professor Josephinekurdziel during the Fall '08 term at University of Michigan.

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Exam 3 Short answers ## - 31 In parakeets two autosomal...

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