In rabbits, fur color is determined by a single gene with two alleles:

Question

dominant allele- black fur (B)
recessive allele- white fur (b)
If a purebred black-furred rabbit (which only produces black-furred offspring when bred with another black rabbit) is crossed with a purebred white-furred rabbit, what will be the ratio of black to white rabbits in their offspring?
1:1
1:2:1
3:1
4:0

Answer 1

In this case, we have two purebred rabbits being crossed:

• The purebred black-furred rabbit has the genotype BB (homozygous dominant).
• The purebred white-furred rabbit has the genotype bb (homozygous recessive).

When these two rabbits are crossed, the offspring will inherit one allele from each parent. The possible genotypes of the offspring will be:

• From the black rabbit (BB): All offspring will receive a B allele.
• From the white rabbit (bb): All offspring will receive a b allele.

Thus, all of the offspring will have the genotype Bb, which will result in black fur since black (B) is the dominant allele.

So, the offspring will all be black-furred rabbits, leading to a ratio of:

• Black to White rabbits: 4:0

Therefore, the correct answer is 4:0.