Biology CLEP Prep Practice Exam 2025 - Free Biology CLEP Practice Questions and Study Guide

The organelle responsible for energy production is the mitochondria. This is because mitochondria are the "powerhouses" of the cell, where cellular respiration takes place. This process converts nutrients into energy in the form of ATP (adenosine triphosphate). This energy is essential for the cell to carry out its various functions. The ribosome is responsible for protein synthesis, the nucleus is responsible for storing and protecting the genetic material of the cell, and the chloroplast is only present in plant cells and is responsible for photosynthesis, not energy production. Therefore, A is the correct answer.