Feather colour in budgies is determined by two different genes: Y for pigment on the outside of the feather, and B for pigment on the inside of the feather. 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 in the offspring is most possible?
A) green offspring only
B) white offspring only
C) blue offspring only
D) blue and white offspring

Question

Quizplus · Accepted Answer

When a blue budgie (yybb) is crossed with a white budgie (yybb), all their offspring will inherit a copy of the recessive alleles for both Y and B, which means their genotype will be yybb. As per the given information, the offspring with the genotype yybb is white. Therefore, the most possible result among the given choices is blue and white offspring. Green offspring are not possible because at least one of the parents must carry the dominant allele for yellow or blue to produce green. Similarly, white offspring are possible, but not the most possible, as the parents can carry the recessive alleles for any colour (Y or B), which make the white offspring possible, but it is less likely to get all white offspring from this cross.

Feather Colour in Budgies Is Determined by Two Different Genes