Kaplan Nursing Entrance Practice Exam 2025 – The All-in-One Guide to Exam Success!

The statement that recessive alleles can only be expressed in a homozygous condition is accurate because recessive alleles require two copies to manifest in the phenotype. In a heterozygous condition, where an individual has one dominant and one recessive allele, the dominant allele's trait will be expressed, effectively masking the presence of the recessive allele. Only when both alleles are recessive (homozygous recessive) does the trait associated with the recessive allele appear in the individual's observable traits.

This understanding is crucial in genetics, as it highlights the relationship between allele combinations and expression of traits. The other options do not reflect the true nature of recessive alleles accurately. Recessive alleles are not expressed when paired with a dominant allele, nor do they dominate others, and they certainly cannot be expressed in a heterozygous condition, as noted. Hence, recognizing that a recessive allele must be present in two copies for expression clarifies the proper context of allele interactions.