What term describes fatty acids with one or more double bonds between carbon atoms and are not fully saturated with hydrogen?

• A. Saturated fatty acids
• B. Unsaturated fatty acids
• C. Trans fatty acids
• D. Polyunsaturated fatty acids

Answer: (B)

Think of how fatty acids are built from carbon chains with hydrogen atoms attached. If there are no double bonds, the chain is fully saturated with hydrogen. When there is one or more double bonds between carbon atoms, the chain cannot hold all possible hydrogens, so it is not fully saturated. That situation describes unsaturated fatty acids.

Within unsaturated fats, one double bond means monounsaturated, while more than one double bond means polyunsaturated. Trans fatty acids are a subset of unsaturated fats where the hydrogen arrangement around the double bond is trans, but the key idea for this item is the presence of one or more double bonds, not full hydrogen saturation.