A biology major would normally take physics during the junior year. Even if the course doesn't end before you take the Spring MCAT, what is left at the end is hardly likely to be a question on the MCAT, and if there is a question, it will be only one. There is nothing to prevent you from reading ahead about one or two weeks of physics.
Most students are locked into the idea of taking the MCAT in April of the third year or August. You can always delay taking the MCAT and applying a year later. Alternatively, there is no requirement that college be finished in exactly four years. If you have to stretch it to five years, do so. Yes, of course there is an extra expense, maybe quite high, but if the cost of finishing in 4 years keeps you out of medical school, it seems to me to be a false economy. You are already heavily invested in your future, financially, timewise and stresswise. Are you prepared possibly to throw all that out the window just not to delay a year in applying or spending another year in college? It seems a false economy to me.
