OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What are the basic components of fats and oils?

1. Fatty acids and ethanol

2. Glycerol and 2 fatty acids

3. Glycerol and 3 fatty acids

4. Glycerol and sterols

The correct answer is: Glycerol and 3 fatty acids

Fats and oils are classified as lipids and are primarily composed of glycerol and three fatty acids. The glycerol molecule serves as a backbone to which the fatty acids are attached through ester bond formation. This structure is commonly referred to as triglyceride, which is the most prevalent form of fat found in the body and in dietary sources. In the case of fats, they are typically saturated and solid at room temperature, whereas oils are generally unsaturated and liquid at room temperature. The presence of three fatty acid molecules influences the properties of the fat or oil, impacting factors such as melting point, health implications, and functional use in both biological systems and food. Other choices do not correctly represent the typical structure of fats and oils. For instance, glycerol with two fatty acids would represent a phospholipid rather than a triglyceride, while the inclusion of ethanol or sterols would not describe the basic components of fats and oils. This makes the chosen answer clear and accurate.