Here is the complete question.
Feather color in budgies is determined by two different genes, Y and B, one for pigment on the outside and one for the inside of the feather. YYBB, YyBB, YYBb or YyBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. A blue budgie is crossed with a white budgie. Which of the following results is possible?
A.) Yellow offspring only.
B.) Blue and white offspring.
C.) a 9:3:3:1 ratio
D.) Green offspring only.
E.) Green and yellow offspring
Answer:
B.) Blue and white offspring.
Step-by-step explanation:
Given that;
Genes exhibiting Green color are ⇒ YYBB, YyBB, YYBb or YyBb
Genes exhibiting Blue color are ⇒ yyBB or yyBb
Genes exhibiting Yellow color are ⇒ YYbb or Yybb
Gene exhibiting White color ⇒ yybb
If we have a blue budgie cross with a white budgie; we will have the following offsprings as illustrated below:
yyBB or yyBb × yybb
Let take yyBb × yybb for example;
if yyBb self crosse; we have: (yB, yb, yB, yb)
if yybb self crossed; we have : (yb,yb, yb, yb)
In a dihybrid cross; the following is shown below for the above traits.
yB yb yB yb
yb yyBb yybb yyBb yybb
yb yyBb yybb yyBb yybb
yb yyBb yybb yyBb yybb
yb yyBb yybb yyBb yybb
∴ we have 8/16 yyBb (blue) and 8/16 yybb (white) offspring.
= 1/2 (blue) and 1/2 (white) offspring.
Therefore, the cross between a blue budgie and white budgie produces blue and white offspring.
