Which choice best defines a System in biology?

• A. A group of individuals of the same species living in a habitat
• B. A set of interacting parts forming a complex whole
• C. A collection of nonliving resources in an environment
• D. A term for the total energy available in an ecosystem

Answer: (B)

In biology, a system is a set of interacting parts forming a complex whole. The parts influence one another and work together to produce functions or properties that the parts alone wouldn’t have, creating an integrated, functioning unit. For example, the circulatory system includes the heart, blood, and blood vessels; their interactions enable blood to be pumped and circulated to tissues, sustaining the organism.

This is why the best choice describes a coordinated, interacting arrangement rather than just a population of individuals, a collection of nonliving resources, or the total energy available in an ecosystem. Those ideas don’t capture the idea of parts that connect and act together to form a functioning whole.