Why is it important to study biology?" is not a scientific question, so it cannot be answered scientifically. Determining the importance of biology is a qualitative judgement, which cannot be addressed by objective measurement and observation.
That said, I feel the study of biology is extremely important in understanding our world, ranging from ethical debates about cloning, stem cell research, and abortion, to the function of our own bodies, to the incontrovertibility of evolution, to the impact the environment has on our quality of life, and the impact we as a species have on the environment. Not to mention, it's just really, really cool.
You can quote me, but I'd better get credit!
Good luck.