Advanced Placement (AP) Biology Practice Exam

What does the term "monosomatic" indicate?

1. Presence of an extra chromosome

2. Only one copy of a chromosome

3. Three copies of a chromosome

4. Two sets of chromosomes

The correct answer is: Only one copy of a chromosome

The term "monosomatic" refers to the presence of only one copy of a specific chromosome in an organism. This term is often used in the context of genetics and chromosomal variations. Typically, organisms are diploid, which means they have two copies of each chromosome—one inherited from each parent. However, in certain genetic conditions or anomalies, an organism may possess only one copy of a chromosome, which is termed monosomy. Understanding that monosomy results in one copy of a chromosome helps clarify how genetic conditions can arise from variations in chromosome number and structure. This concept is fundamental in genetics, particularly in studying developmental anomalies or disorders caused by chromosomal abnormalities. Therefore, identifying monosomatic conditions can provide insight into certain genetic disorders and contribute to understanding human genetics more broadly.