Question

What exactly is dominance? Why are some alleles dominant and some recessive?

Answer 1

dominant alleles are alleles that are expressed to a greater extent in progeny ad compared to other alleles.the other alleles can be called recessive alleles as they are surely present in genotypic structure but are not expressed as phenotype

Answer 2

Answer:

(i) Every gene contains information to express a particular trait.

(ii) In a diploid organism, there are two copies of each gene, i.e., as a pair of alleles.

(iii) The two alleles may be identical (homozygous) or different (heterozygous).

(iv) One of them may be different due to some changes that it has undergone which modifies the information  that particular allele contains.

(v) If the modified allele produces a non-functional enzyme or no enzyme the phenotype will be affected.

(vi) The unmodified (functioning) allele, which represents the original phenotype is dominant allele.

(vii) The modified allele is generally recessive allele.

(viii) The recessive trait is seen due to non-functional enzyme or because no enzyme is produced.