Which of the following best describes an autosome?

An autosome is best described as a non-sex chromosome. In organisms, chromosomes are categorized into autosomes and sex chromosomes. The autosomes are those chromosomes that do not play a direct role in determining the sex of an individual. In humans, there are 22 pairs of autosomes and one pair of sex chromosomes (XX or XY).

The defining characteristic of autosomes is that they carry genes that are responsible for various traits and functions unrelated to an organism's sex. This means that they are involved in numerous biological processes, influencing characteristics such as physical features, metabolic pathways, and other hereditary traits.

While the other choices touch upon various aspects of chromosomes, they do not accurately capture the defining role of an autosome. For instance, the option mentioning chromosomes that determine sex incorrectly associates autosomes with sex determination, which is not their function. The options regarding unique functions and the existence of chromosomes in pairs also misrepresent the broader role of autosomes, which are not restricted to pairs in a singular unique function. Overall, the term ‘non-sex chromosome’ directly and simply delineates what an autosome is, focusing on its classification rather than its function or peculiarities.