Identify the characteristic structural feature of cholesterol.

Identify two other types of lipids found in the human body.

State what the terms HDL and LDL represent.

Compare the structures of linoleic acid and linolenic acid.

steroid/steroidal backbone/4 ring/tetra cyclic carbon structure skeleton;

Do not accept OH, hydroxyl, hydroxide, alcohol.

Accept a correct sketch of the steroid backbone.

phospholipids;

triglycerides/triglycerols;

high density lipoprotein and low density lipoprotein;

both have 18 carbon atoms;

both have carboxyl/COOH;

linoleic acid has 2 double bonds and linolenic 3 / linoleic acid has less double bonds / linoleic acid is less unsaturated;

first double bond of linoleic is after the \({{\text{6}}^{{\text{th}}}}\) C atom and first of linolenic is after the \({{\text{3}}^{{\text{rd}}}}\) C atom from the end of the \({\text{C}}{{\text{H}}_{\text{3}}}\) group/counting from side of the chain that does not have COOH group / linoleic acid is omega-6 and linolenic acid is omega-3 / OWTTE;

Most candidates identified the steroid backbone.

Many candidates named only one other type of lipid.

Some candidates stated correctly the terms of HDL and LDL.

Most candidates compared at least two features of the structures of linoleic and linolenic acid.