NEET BIOLOGY

Detailed explanation-1: -All the offspring that have brown eyes will have to be heterozygous with the genotype Bb (B allele inherited from the father and b allele from the mother). Crossing Bb x bb will give 50% of the offspring as heterozygous (Bb) with brown eyes and the other 50% as homozygous recessive (bb) with blue eyes.

Detailed explanation-2: -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.

Detailed explanation-3: -For two parents with brown eyes to have a blue-eyed child, both parents must genetically be Bb. When this happens, there is a 1 in 4 chance that these parents will have a bb child with blue eyes. Unfortunately, eye color is not as simple as this.

Detailed explanation-4: -Someone with brown eyes may be carrying one blue allele and one brown allele, so a brown-eyed mother and a blue-eyed father could give birth to a blue-eyed child.