
Answer and Explanation:
cross: BbTt x bbTt
Cross for B gene
Parental ) Bb  x  bb
Gametes) B  b  b  b
Punnet square) Â B Â Â b
         b   Bb   bb
         b   Bb   bb
F1) Genotypic proportion: 2/4=1/2 Bb : 2/4=1/2 bb
   Genotypic ratio 1:1
   Phenotypic proportion: 2/4=1/2 B- : 2/4=1/2 bb
   Phenotypic ratio  1:1
Cross for T gene
Parental ) Tt  x  Tt
Gametes) T  t   T  t
Punnet square) T Â Â Â t
         T   TT   Tt
         t    Tt   tt
F1) Genotypic proportion 1/4 TT
                     2/4 Tt
                     1/4 tt
   Genotypic ratio  1 : 2 : 1
   Phenotypic proportion: 3/4 T-
                       1/4 tt
   Phenotypic ratio 3 : 1