The two biochemical pathways for coat color pigment in a species of triblles are shown below. The final color of the tribble is the combination of colors produced by the two pathways. If both blue and yellow pigments are produced, the coat color is green. If both blue and red pigments are produced, the color is purple. If both red and yellow pigments are produced the coat color is orange. Note that the presence of a dominant allele at a locus causes the production of the enzyme and the reaction proceeds. The homozygous recessive condition at a locus prevents that reaction from proceeding.
A_ B_
Yellow Precursor ? ? Red Intermediate ? ? Blue End Product
aa bb

C_ D_
Red Precursor ? ? Blue Intermediate ? ? Yellow End Product
cc dd
a. Give the phenotype for each genotype below:
AaBbccDd ______________ AabbCcDD ____________
b. A cross was conducted between tribbles of genotype AaBbccDd x AabbCcDD . Put whole numbers in the statement below to indicate the phenotypic ratio of the progeny from this cross. Show your work using a branch diagram. Be sure to put hash marks through lower case allele abbreviations when the upper and lower case look alike.
____ Yellow : ____ Blue : ____ Red : ____ Green : ____ Orange : ____ Purple