A: Whales are marine mammals but scientists now think that whales are descended from terrestrial ancestors. Use your understanding of the evolution of the mammals to explain why this might be the case. What evidence might you find in the skeletons of modern whales which would support the suggestion?
B: Whales and sharks have many body features which are similar (e.g. fins and a streamlined shape) but a close relationship is not reflected in an analysis of their DNA. With explicit reference to species concepts, explain how and why the relationship between a whale species and a shark species, which was estimated from the DNA, might differ from the relationship estimated from their physical features?