Answer:
Different versions of a single gene are called alleles and one can be dominant, the other's recessive.
Step-by-step explanation:
An allele is one of the different forms or versions of a gene. A dominant allele is phenotypically expressed over another allele and shows its effect even if the individual only has one copy of the allele. The recessive allele is only expressed in the absence of a dominant allele and shows its effect only if the individual has two copies of the allele. A homozygote possesses two copies of the same allele, while heterozygote possesses two different alleles.
The phenotype of an organism means its physical appearance and genotype is the genetic code, which is the combination of alleles inherited from the parents. Co-dominance is the condition in which both the alleles are fully dominant and both the alleles for a specific trait is equally expressed. Incomplete dominance is the condition in which one allele does not dominate or mask the other while displaying a new trait.