Question

In man, the blue eye colour is recessive to the brown eye colour. If the boy has brown eyes and his mother is blue eyed, what would be the phenotype of his father?
A)Black eye
B)Brown eye
C)Green eye
D)Blue eye

Answer 1

Hint: When the connected allele is dominant, dominant traits are still displayed, even though only one copy of the dominant trait occurs. Recessive characteristics are only displayed if any of the corresponding alleles are recessive.

Complete answer:
Blue eyes in humans are recessive and brown eyes are dominant. In the case of male human beings - XY (Only X chromosome can carry genes, but Y cannot). In the case of female humans - XX (Both X chromosomes will carry genes). If the son has brown eyes, XB Y Y is his predicted genotype. The genotype of a blue-eyed mother is XbXb. Therefore the father's genotype needs to produce one B gene that has been passed to the offspring. The father genotype is XB Y- The phenotype is brown eyes.

Examples of Dominant Characteristics :
1)Black hair over blond or red hair is dominant.
2)Curly hair prevails over smooth hair.
3)Baldness is a dominating feature.
4)Giving a widow's peak (a V-shaped hairline) to having a straight hairline is dominant.
5)Both manifestations of a dominance characteristic are freckles, cleft chin and dimples.

Hence, the correct answer is option (B)

Note: In total domination, the phenotype sees only one allele in the genotype. Both alleles in the genotype are seen in the phenotype during codominance. In incomplete dominance, in the phenotype, a combination of the alleles in the genotype is seen.