Advanced Placement (AP) Biology Practice Exam

Which type of chromosomes does not determine sex?

1. Sex chromosomes

2. Homologous chromosomes

3. Autosomes

4. Sister chromatids

The correct answer is: Autosomes

The correct choice is based on the fact that autosomes are chromosomes that do not play a direct role in determining an individual's sex. In humans and many other organisms, there are two types of chromosomes: sex chromosomes and autosomes. The sex chromosomes, which consist of X and Y chromosomes, are directly responsible for determining the sex of an organism. On the other hand, homologous chromosomes refer to pairs of chromosomes (one from each parent) that are similar in shape and size and carry the same genes, but they may have different alleles. While these homologous chromosomes include both autosomes and sex chromosomes, the term itself does not specifically differentiate those that determine sex. Sister chromatids are identical copies of a chromosome that are formed during DNA replication and play a role in the process of cell division but do not determine sex. Therefore, autosomes represent the majority of an organism's chromosomes and are involved in coding for traits unrelated to sex, distinguishing them from sex chromosomes which are specifically linked to sex determination.