Hello!
I'm in the process of finishing my M.A. in Biology now. It's been a great road - I've loved combining research with upper level biology courses - it has dramatically helped my application.
If your undergrad sGPA is not where you want it to be, I highly suggest this route. As long as you are willing to spend the year or two to finish the Master's degree. This is where the ADCOM will see if you are truly dedicated!!
Best of luck and feel free to ask me any other questions!