Weed Out Classes?

Hey fellas.
I know there are bad stigmas in regards to pre meds, but I am genuinely interested in the field, particularly in vascular medicine. I would just like to know which classes are considered weed out, so I can prepare accordingly. Are Bio-L112 and C117 weed out classes? If so, what are some things I can do this summer to ensure I am ready for these courses.
Thanks

Also, what are some good profs for these classes. thanks

For profs use:

http://gradedistribution.registrar.indiana.edu/

http://www.ratemyprofessors.com/