<p>Bio/Chem/Phys are definitely not compulsory…
If you take a class pass/fail then you have to complete all the required work for the course (take the tests, write the papers etc.) Showing up may or may not be compulsory but it’s always advisable! You also have to get a passing grade, but don’t worry, it’s pretty hard to fail classes at Penn. Whatever grade you get won’t show up on your transcript, you just get a P. And if you eventually decide that you would like your grade to be on your transcript you can petition the registrar to get it changed to a letter grade…AFAIK the instructor doesn’t know if you take the class P/F or not and assigns you a letter grade, then the P/F part is taken care of by the registrar.</p>