Question 19M.1.SL.TZ1.8

In this question candidates had to combine their understanding of insulin and of proteins to make a deduction. From 2.4 of the Core they should know both that insulin is a protein and that amino acids in polypeptides or proteins are linked by peptide bonds. There was criticism that this was not a fair task. The question certainly proved difficult for many, with only a third answering it correctly and nearly half thinking that insulin contains glycerol rather than peptide bonds. The discrimination index was lower than had been hoped but was acceptable. There have been many complaints from teachers in the past that multiple-choice questions test only insignificant factual knowledge. Efforts to make sure that this is not the case have been increased, but the challenge of questions will inevitably be greater, as in this case.