Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What defines an allele?

1. A pair of identical genes inherited from both parents

2. An alternative version of a gene

3. A specific location on a chromosome

4. An organism's visible traits

The correct answer is: An alternative version of a gene

The definition of an allele is indeed tied to it being an alternative version of a gene. Genes exist as segments of DNA that code for specific traits, and alleles are the different variants that can occur at a given gene locus. For example, a gene that determines flower color might have a blue allele and a white allele. Each allele can lead to different expressions of that trait, which is crucial for the concept of genetic diversity and inheritance. Understanding alleles is fundamental in genetics because they not only contribute to different phenotypes (observable characteristics) in organisms but also play a critical role in heredity. During reproduction, offspring receive one allele from each parent, which influences various physical traits and biological functions. The other choices do not accurately capture what an allele is: a pair of identical genes would refer to homozygous genotypes, a specific location on a chromosome describes a locus and visible traits are outcomes of allelic expressions rather than the alleles themselves. Hence, recognizing that alleles are simply alternate forms of a gene is essential in genetics.