NEET BIOLOGY

Detailed explanation-1: -Recessive alleles are only expressed when no dominant allele is present. In most sexually reproducing organisms, each individual has two alleles for each gene (one from each parent). This pair of alleles is called a genotype and determines the organism’s appearance, or phenotype.

Detailed explanation-2: -Recessive alleles only show their effect if the individual has two copies of the allele (also known as being homozygous?). For example, the allele for blue eyes is recessive, therefore to have blue eyes you need to have two copies of the ‘blue eye’ allele.

Detailed explanation-3: -Alleles can be dominant or recessive. Dominant alleles mask the effects of recessive alleles, so a recessive trait is only expressed when an organism has two recessive alleles for a gene.

Detailed explanation-4: -Recessive alleles are only expressed if both of a person’s alleles are recessive. If a person has one dominant allele and one recessive, he is called a carrier. This is because he expresses the dominant trait, but “carries” the recessive trait. An example of this is albinism.

Detailed explanation-5: -An allele is considered dominant when it masks the expression of the recessive trait in a heterozygous genotype. When you are homozygous for a recessive allele, the phenotype expressed is the recessive trait. If you are heterozygous, one of each, the dominant trait is expressed.