Most flour beetles are black, but several color variants are known. Crosses of pure-breeding parents produced the following results in the F1 generation, and intercrossing the F1 from each cross gave the ratios shown for the F2 generation. The phenotypes are abbreviated B1, black; Br,
brown; Y, yellow; and W, white.
Cross Parents F1 F2
1 Br X Y Br 3 Br: 1Y
2 B1 X Br B1 3B1: 1 Br
3 B1 X Y B1 3B1: 1 Y
4 W X Y B1 9 B1: 3 Y: 4 W
5 W X Br B1 9B1: 3 Br: 4 W
6 B1 X W B1 9B1: 3 Br 4 W
a) From these results, deduce and explain the inheritance of these colors.
b) Arrange the genes and pigments into a biochemical pathway or pathways.
c) Write out the genotypes of each of the parents, the F1, and the F2 in crosses 4 and 6