How do I tie my application together?

I have a lot of interests which seem to not tie together very well. I am president of Model UN (I do a lot of stuff with MUN), founded a political debate club, and do other world affairs things like Junior World Affairs Council and am thinking of starting a World Cultures Club. I also have a strong interest in biology, am going to start a independent research project, interned for a biology nonprofit, and are applying to summer research and bio programs. I also volunteer on the side for multiple nonprofits that have nothing to do with either of those. In addition, I edit for my schools literary magazine and joined the school newspaper recently. I have no idea to tie any of these together into a cohesive story. My thought was bioethics, but I dont know. Any advice?