What is the role of alleles in genetics?

Alleles are indeed variations of a gene that contribute to the diversity of traits within a species. Each gene can have multiple forms, called alleles, which arise from mutations and lead to different phenotypic expressions. For example, in pea plants, the gene for flower color can have a purple allele and a white allele, determining the color of the flowers based on which alleles are present.

The variations provided by different alleles are crucial for the process of natural selection and evolution, as they create a range of traits that can be subject to selective pressures. In addition, alleles can be homozygous (identical variants) or heterozygous (different variants), influencing an individual's genotype and phenotype.

The other options do not accurately describe the role of alleles. Chromosomes are determined by the overall genetic makeup rather than individual alleles. RNA plays a different role in genetics and is not made up of alleles. Cellular respiration is a process related to energy production in cells and does not involve alleles directly. Thus, the function of alleles as variations of genes that can lead to different traits is fundamental to understanding genetics.