Answer:
The two copies or forms of a gene for one trait are called alleles.
Explanation:
- Alleles of a gene are formed due to a mutation at same locus of chromosome.
- Alleles can be a) dominant,
b)recessive or
c) null alleles.
- A dominant allele always expresses itself in the phenotype and masks the effect of recessive allele.
- The recessive allele could express itself only in the absence of dominant allele.
- A null allele is the one that lacks the normal gene function.
