A Level Biology Practice Exam

Which of the following describes the function of glycerol?

1. A primary energy source for cellular respiration

2. An alcohol component found in triglycerides

3. A structural protein in muscle tissue

4. A polysaccharide for energy storage

The correct answer is: An alcohol component found in triglycerides

The function of glycerol is accurately described as being an alcohol component found in triglycerides. In biochemistry, triglycerides are a type of lipid formed from glycerol and three fatty acids. Glycerol serves as the backbone of these triglycerides, linking the fatty acids together. This structure is crucial for the storage of energy in the form of fat, as triglycerides are the primary storage form of fats in the body, providing a dense source of energy. The other choices highlight functions or compounds that do not relate to glycerol. For instance, while many organisms do utilize carbohydrates and fats for cellular respiration, glycerol itself is not a primary energy source. It can be converted into glucose and used in energy metabolism, but this is not its main function. Similarly, glycerol does not act as a structural protein in muscle tissue; proteins such as actin and myosin serve that purpose. Lastly, glycerol is also not a polysaccharide; polysaccharides are long chains of sugar molecules used primarily for energy storage and structural support in organisms. Thus, the choice that identifies glycerol as an alcohol component in triglycerides is the most accurate.