In The Island of Dr. Moreau, Wells tackles the relationship between science and ethics. In his day—as in ours—science had produced unprecedented technologies and revelations about the world. It was all great stuff, and we'd be a wholly different society today without these advancements. For example, this website you're reading now wouldn't exist, and your science textbooks would be less than a quarter their current size—good for homework; bad for everything else. But discoveries like the theory of evolution left people worried that scientific endeavors were destroying the so-called pillars of society, like religion and morality. Others thought science had lost its ethical compass all together (we're looking at you, vivisection). Wells's goal is to explore these issues raised by science and morality. If this all sounds familiar, it's because we are still facing the same questions about science today.
The science in The Island of Dr. Moreau is more fantasy-like than scientifically accurate. This is because a focus on actual science would have taken away from novel's ability to openly explore the questions it raised. Also, it's science fiction.
Prendick's scientific background allows the reader to trust his experiences on the island more than if he were ignorant of the field, giving the novel more of a sense of truthfulness.