Start of broadly by discussing how the study of morphology may have influenced the creation of the Linnaean system of classification (K, P, C, O, F, G, S). Then go into some of these individual taxa and describe how the classifications within those have changed over time. I think the easiest one would be kingdom where you can talk about the animals, plants, bacteria, etc. Not sure if morphology can include cell structure (I don't remember much of prelim bio) but if it does count, thats a good place to start. Looking through microscopes scientists would have quickly realised differences between certain types of organisms.
Its a tricky question because the two parts are hard to combine into one response, but I think you just need to think of some good examples you studied and go from there. The first example that come to my mind are the studies done on animal bone structures (like pentadactyl limbs in whales, bats, humans) to show evolution.
Another is morphological studies done showing that some animals have a backbone but others do not (so here you have some differentiation which led to the creation of the phylum). Remember also how some fish are boney, others are cartilaginous, etc.
Another example is when the fungi kingdom was formed because it was discovered that fungus wasn't a plant (because fungus has chitin in its cell walls whereas plants have cellulose). Unfortunately this probably doesn't fall under morphology though.
This last example I took from the topic on convergent and divergent evolution (which I can't remember if it's HSC or prelim) and involves 3 completely different species that look extremely similar but have nothing in common except for appearances. The icthyosaur was a reptile that lived in the oceans, the dolphin is of course a mammal, and a shark is a fish. You can try relate this to morphology and discuss how an early scientist who classified living things based off only size, shape and appearance would have been very wrong about their method.
Best of luck!
