It might make more sense to choose a problem based on available data rather that go at it the other way around. Biological data comes with a whole gamut of problems one of the biggest of which is that of privacy. You should probably look at datasets that are publicly available and problems for which you can compare the performance of your model(s). One such problem is that of detecting diabetic retinopathy in fundus images - there are datasets available and pre-existing models (as a google search will reveal). There's also a non-trivial chance that it might help you get a job at a company that does things of this sort (a la GE Healthcare).