Which of the following types of information are needed to construct a karyotype?

I. Size of the chromosomes
II. Gene mutations of the chromosomes
III. Age of the individual

A. I only
B. II only
C. I and II only
D. I, II and III

A

More candidates chose response C instead of A, the correct answer, so the question discriminated well. A comment on the G2 forms suggested that shape was also a property that students would be expected to know, and this was not an option in the responses. It was felt that often not all possible information is included in questions, and that it was a fair set of options.