Answer:
This question is incomplete, the options are:
A. Two copies of the allele that determines phenotype whenever the allele is present
B. Two copies of the allele whose effect is hidden unless the other allele is absent
C. One copy of the allele that determines phenotype when present and one copy of the other allele
D. One copy of each of two alleles that both contribute equally to determining phenotype
The answer is B.
Explanation:
According to Gregor Mendel, a Gene comes in two alternative forms called ALLELES. One allele called the DOMINANT ALLELE is capable of masking the phenotypic expression of the other called the RECESSIVE ALLELE. The dominant allele will always express itself whenever it is present. However, a recessive trait will only be expressed when two alleles for recessiveness occur in the gene.
An individual whose genotype is for the recessive allele will have two copies of the allele whose effect is hidden unless the other allele is absent. This means that in that particular gene, the two present alleles will be recessive alleles.
