NEET BIOLOGY

Detailed explanation-1: -Brown eye colour is dominant over blue eye colour. Therefore, for the brown-eyed parents having blue-eyed child, the possibility is that both have heterozygous genotype i.e. Bb. Therefore, from the square below, it is clear that there is a 25% possibility of blue-eyed (bb) child.

Detailed explanation-2: -Both parents with green eyes: 75% chance of baby with green eyes, 25% of baby with blue eyes, 0% chance of baby with brown eyes. One parent with brown eyes and one parent with blue eyes: 50% chance of baby with brown eyes, 50% chance of baby with blue eyes, 0% chance of baby with green eyes.

Detailed explanation-3: -A couple’s children can have almost any eye color, even if it does not match those of either parent. Currently it is thought that eye color is determined by about six genes, so you can imagine how inheritance of eye color becomes very complicated.

Detailed explanation-4: -Of these three genotypes, only bb, the homozygous recessive genotype, will produce a phenotype of blue eyes. The heterozygous genotype and the homozygous dominant genotype both will produce brown eyes, though only the heterozygous genotype can pass on the gene for blue eyes.