GED Science Practice 2025 – 400 Free Practice Questions to Pass the Exam

The correct answer is fatty acid. Fatty acids are crucial components of lipids, which are organic compounds that include fats and oils. These molecules typically consist of long hydrocarbon chains that end with a carboxyl group (-COOH), which classifies them as monocarboxylic acids. They play vital roles in energy storage, cellular structure, and signaling within the body. The presence of a carboxyl group allows them to participate in chemical reactions that form ester bonds, leading to the creation of complex lipids like triglycerides and phospholipids, which are essential for cell membranes and energy reserves.

The other options do not accurately represent this specific class of compounds within lipid molecules. For instance, excretion pertains to the process of eliminating waste from the body, fallout refers to particles that fall to the ground after an explosion or disaster, and feilation is not a term commonly associated with organic chemistry or lipids. Thus, fatty acid is the term that correctly describes these important lipid components.