one year away from a BS in Biology but thinking about switching paths

You may be putting the cart before the horse. Nursing schools are super-competitive to get into right now something with lengthy waiting lists - I don't know about PT programs. You may want to keep your options open if you don't get accepted to nursing right away. Nursing salaries do not keep pace with those of PT in the long term. Physical Therapists are able to function as independent contractors - in today's environment nurses are not.

There is no way to escape med surg for beginning nurses - it is the basic training ground and (with rare exceptions) where new grads are started. Transitioning to a specialty care are may take quite a while. Advanced practice areas such as CRNA, require advanced degrees - have a pre-requisite of very specific amounts of clinical experience in a certain area.

I would encourage you to do some investigation of nursing to get beyond the popular myths. If possible, spend some time with 'real' nurses in your area - job shadow if possible. The scope of nursing practice is wider than that of PT, so there is less likelihood of boredom. However that is also a weakness - nurses are constantly having to cope with new or unfamiliar situations and this is very stressful since mistakes in judgement can have a lasting effect on people's lives, including that of the nurse. This site is a great place to gain insight on the realities of nursing. Take a look at the "First year in nursing" forum.

Good Luck!