A Level Biology Practice Exam

An organ is correctly defined as a structure made up of different types of tissues that work together to perform a specific function within an organism. Each tissue in the organ has distinct roles that contribute to the overall operation of the organ. For example, in the heart, muscle tissue contracts to pump blood, while connective tissue forms the structure that holds the organ together.

In contrast, other statements fall short in accurately describing an organ. The first statement suggests that an organ consists of a single tissue, which is not correct, as organs typically rely on multiple types of tissues to function effectively. The third statement incorrectly defines an organ as the smallest unit of life, which would be a cell, not an organ. Finally, the fourth statement refers to macromolecules, which do not constitute an organ but rather the molecular building blocks within cells and tissues. Thus, understanding the composition and role of various tissues helps explain why the definition provided is the most accurate.