<p>If you’re asking this because you’re worried that biology PhD programs will be looking for physics classes, they likely won’t care whether you retake intro physics or not. They’ll be more concerned with your ability to do advanced work in biology (which can be demonstrated by upper-level courses in biology and your GPA) and in your ability to do research (which can be demonstrated by research experience and letters of rec). For PhD programs, unless they list specific prerequisites, you don’t need to have physics classes on your transcript just for the sake of showing that you took physics.</p>