The table shows certain characteristics present (+) or absent (–) in six organisms.

Using the data, label the cladogram with the names of the organisms.

A species is often defined as a group of similar individuals that interbreed in nature and produce fertile offspring. Discuss some problems with the use of this definition.

Award [1] for the correct position of any two organisms.
Award [1 max] if the correct order is reversed horizontally (ie from cat on the left to Amoeba on the right).

a. not all organisms can be defined in this way / does not take into account hybrids/ microorganisms/plants;
b. (even if able to interbreed) may have differences in DNA/protein;
c. does not apply to bacteria/other organisms that reproduce asexually;
d. in sympatric/allopatric isolation members of the same species do not interbreed;
e. (in some species) significant differences in morphology can occur within the same species eg: sexual dimorphism/metamorphosis/ring species;
Accept any other correct answer.

The majority of candidates could label the cladogram correctly, although a certain number did it backwards.

Many candidates presented a good discussion about the use of species definition, but many others could not express their ideas clearly enough or only had a vague idea.