Transfer Credits?

<p>I’m a long way away from getting in as a transfer to Penn for next year- but just on the long shot that I do- I have heard that credits are difficult to transfer over, does anyone have any knowledge or experience with how this generally goes? What classes will they usually take? If i were to take a bio course with lab at city college this summer to get it out of the way so I can focus on my major at Penn, would this be a waste of time and would they ask me to take it while at Penn? Thanks for any help.</p>