The diagram below represents the human eye. State the names of structures I, II, III and IV.

I. ..................................................................

II. ..................................................................

III. ..................................................................

IV. ..................................................................

Outline the evidence provided by DNA for the common ancestry of living organisms.

The cladogram below shows the classification of species A to D. Deduce how similar species A is to species B, C and D.

Suggest two reasons for using cladograms for the classification of organisms.

I. cornea;
II. lens;
III. vitreous humour;
IV. choroid; (Accept sclera as line is on the border between these two)
Two correct for [1] and four correct for [2].

all living organisms use DNA as genetic/hereditary material;
genetic code is (almost) universal;
idea that mutations accumulate gradually in DNA;

A is most similar to B;
A is equally similar to C and D;
A is least similar to both C and D;

methods used to prepare cladograms use a different approach from traditional classification/taxonomy;
show ancestral relationships;
reflect how recently two groups shared a common ancestry;
cladograms are (objective/accurate because they are usually) based on molecular differences;
they should be considered as a good complement to traditional classification;

Candidates did surprisingly poorly on this simple task of naming the structures of the eye. The label line for IV was on the border of the choroids and the sclera, and thus either one was accepted as correct.

This was poorly done.  Some correctly indicated that DNA was the genetic or hereditary material for all living organisms and that the genetic code is universal. Many wrote about pentadactyl limbs, DNA being made of 20 amino acids or about chimps and humans which did not get marks. 

Many candidates correctly interpreted the cladogram, deducing that A and B were most similar. Some were able to get a second point.

Many were able to get one mark for indicating that cladograms showed ancestral/evolutionary relationships but only a few got the second mark for another reason for using cladograms.