Penn Foster Biology – The Cell Practice Test 2025 - Free Biology Practice Questions and Study Guide

The smooth endoplasmic reticulum is primarily responsible for detoxifying harmful substances in the cell. This organelle plays a crucial role in lipid metabolism and the synthesis of steroid hormones, and it is equipped to process various toxins and drugs that could potentially harm the cell. The abundant presence of the smooth endoplasmic reticulum in liver cells is an excellent example of its function in detoxification, where it helps to convert fat-soluble toxins into water-soluble forms that can be excreted from the body.

The mitochondria are mainly involved in energy production through the process of cellular respiration and ATP generation, rather than detoxification. The Golgi apparatus is primarily responsible for modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles. The lysosome contains digestive enzymes that break down waste materials and cellular debris, but its primary function is not detoxification; it is more focused on recycling and degrading macromolecules within the cell. Thus, the smooth endoplasmic reticulum stands out as the key organelle for detoxifying harmful substances in cellular processes.