Classification and the species conceptEdexcel A-Level Biology B: Mind map

Exam questions on Classification and the species concept

1. Researchers collected several specimens of an unfamiliar beetle from the canopy of a rainforest. All the specimens are female, no males have ever been found, and the beetles are thought to reproduce without mating.
   Suggest how the researchers could use DNA to decide whether the beetle is a new species.2 marks
2. Gel electrophoresis was used to compare DNA from four related species of finch, A to D. DNA from each species was cut with the same restriction enzyme and the fragments were separated on an agarose gel. Species A and B shared five of their six bands, species A and C shared three bands, and species A and D shared only one band.
   Explain why the smaller DNA fragments are found further from the wells at the end of the run.2 marks
3. Until the 1970s, living organisms were classified into five kingdoms: Prokaryotae, Protoctista, Fungi, Plantae and Animalia. In 1977 Carl Woese compared the base sequences of ribosomal RNA from many organisms. He found that the prokaryotes fell into two groups, bacteria and archaea, which differed from each other as much as each differs from the eukaryotes. Archaea also differ from bacteria in the lipids of their membranes and in their RNA polymerase.
   Explain how Woese's evidence supports the three-domain model rather than the five-kingdom model.3 marks