Hello, 
Thank you for your question! While I would say that both three of these are excellent classes to gain physiological knowledge for the MCAT, I would personally recommend BIOLOGY 225. Because biology 225 will count as an upper-level biology class for a lot of medical schools, and biology 226 will count as the upper-level biology lab that medical school would also like to see. Furthermore, it would be better to learn physiology from the biology standpoint instead of the public health standpoint just because MCAT is tailored that way. Again, this is only from my personal experience and what I know about these classes. I hope this helps a little! If you have more questions, feel free to ask it here or come to the virtual advising OH every Monday-Wednesday from 6 pm-10 pm. The link can be found on the website! 
Haitong  Peer advisor