A Level Biology Practice Exam

What characteristic does an unsaturated fatty acid have?

1. Single carbon bonds

2. Two double carbon bonds

3. No carbon bonds

4. Only triple carbon bonds

The correct answer is: Two double carbon bonds

An unsaturated fatty acid is characterized by the presence of one or more double bonds between the carbon atoms in its hydrocarbon chain. The correct answer highlights that unsaturated fatty acids can indeed contain two double bonds, which is specific to certain unsaturated fatty acids known as polyunsaturated fatty acids. In contrast, monounsaturated fatty acids contain only one double bond. The presence of double bonds introduces kinks in the fatty acid chain, affecting the fluidity and melting point of the fats they comprise. Understanding the role of carbon bonds is crucial. Unsaturated fatty acids differ from saturated fatty acids, which contain no double bonds and only single carbon-carbon bonds, impacting their structure and function in biological systems. Therefore, the presence of multiple double bonds in specific types of unsaturated fatty acids is a crucial defining feature.