to black body. Each locus is located on a separate autosome. Knowing that the Pilies are
homozygous, work the following crosses through the Fa generation to determine the genotypic
and phenotypic ratios for each generation. A. Pi Bristled, gray X hairless, black B. P1 Hairless,
gray X Bristled, black C. P1 Bristled, gray X hairless, gray
Solution
6. Ans-
A.
P1------- Bristled gray × Hairless black
Genotype---- BBGG bbgg
Gametes---- BG bg
F1------ BbGg
(Bristled gray)
Cross------- BbGg × BbGg
Gametes---- BG Bg bG bg
F2-----
BG Bg bG bg
BG BBGG BbGg BbGG BbGg
(Brist Gray) (Brist. Gray) (Brst. Gray) (Brst. Gray)
Bg BBGg BBgg BbGg Bbgg
(Brst. Gry) (Brst black) (Brst.gray) (Brst. Black)
bG BbGg BbGg bbGG bbGg
(Brst. Gry) (Brist gry) (Hairls. Gry) (hairls. Gry)
bg BbGg Bbgg bbGg bbgg
(Brst. Gry) (Brst. Blck) (hairls. Gry) (hairls. Blck)
Phenotypic ratio= 9:3:3:1 ( Brist Gray: Brst black :Hairls. Gry: hairls. Blck)
Genotypic ratio= 1:2:1:2:4:2:1:2:1
BBGG=1 BbGg=2 bbGG= 1
BbGg=2 BbGg=4 bbGg= 2
BBgg=1 bbgg=2 bbgg= 1
B.
P1------- Hairless gray × Brist. Black
Genotype---- bbGG BBgg
Gametes---- bG Bg