American Academy of Professional Coders (AAPC) Practice Exam

What is defined as a basic unit of all living things?

1. Organ

2. Tissue

3. Cell

4. System

The correct answer is: Cell

The correct answer is the cell, as it is the fundamental building block of all living organisms. Cells are the basic structural and functional units of life, serving as the smallest unit of matter that can carry out all life processes. Every organism is composed of one or more cells, and each cell performs essential functions, such as metabolism, energy production, and reproduction. In multicellular organisms, cells group together to form tissues, which then organize to form organs. Organs can further come together to create systems that perform complex biological functions. While organs, tissues, and systems are all vital components of living organisms, they are composed of cells, which are the essential starting point for life.