Question

In humans, the allele for dimples (D) is dominant to the allele for no dimples (d). At another gene locus, the allele for broad eyebrows (B) is dominant to the allele for slender eyebrows (b). These two allele pairs assort independently. A man who is heterozygous for both traits marries a woman who has no dimples and who is heterozygous at the gene locus controlling eyebrow width. Complete the sentences about this dihybrid cross with the correct terms.Genotype of the man is _______.
Genotype of the woman is _______.
Genotype of the gametes produced by the man is ________.
Genotype of the gametes produced by the woman is ________.
Probability that there first child will have dimples ________.
Probability that there first child will have dimples and slender eyebrows _________.

Answer 1

Answer:

1. DdBb

2. ddBb

3. DB, Db, dB and db.

4.  dB and db.

5 50% or 1/2

6. 1/8

Explanation:

As given, Allele for dimples(D) is dominant over alleles for no dimples (d), so D  is dominant over d.

Allele for broad eyebrows (B) is dominant over allele for slender eyebrows (b), so B is dominant over b.

A man heterozygous for both traits ( DdBb) marries a women who has no dimple and heterozygous fro eyebrow (ddBb)

So cross is =  DdBb × ddBb

1). Genotype of the man is DdBb.

2). Genotype of the woman is ddBb.

3). Genotype of the gametes produced by the man are DB, Db, dB and db.

4). Genotype of the gametes produced by the woman are dB and db.

5). Probability that their first child will have dimples 50% or 1/2

6). Probability that there first child will have both dimples as well as slender eyebrows 1/8