Group projects are a fact of life, both in school and in many other settings as well.
It has been stated that in any group 80% (or more) of the work is done by 20% (or less) of the members. Observation of whatever group you are in (committee, church, PTA, etc.) will confirm this assessment.
Unfortunately, those of us who are that 20% end up doing it in whatever situation we are in because we are the 'worker bees' and just are going to get it done anyway, whether or not the others pull their share of the load.
Being a team player IS important, ask any employer and they will tell you that some of their most valuable employees are the ones who can 'work with anybody and everybody', do their part (and maybe a bit more) and are the ones who will be sure a task gets done.
Be proud to be a 'worker bee', but don't volunteer for more than you can handle comfortably...voice of many years experience speaking here. I've learned (finally, I hope) that just because I CAN do something, doesn't mean I have to be the one TO do it every time.
Good luck and congratulations on that A!