If a student has a high GPA, excellent GRE scores, relationships with professors and outstanding letters of recommendation, strong research positions and internships, etc… then that student will not have any trouble getting into grad school coming from UNC or almost any other school.
If a student has a relatively low GPA, no/little research, weak relationships with professors etc… then getting into grad school may not be so easy regardless of school.
The answer to the original question- will graduating from Vanderbilt with a 3.3 have an edge in grad school admissions for biology over a 3.7 from UNC, all things being equal… My answer is still no. The OP is grossly underestimating UNC.
Are there people on admissions committees who give certain people the benefit of the doubt coming from certain schools because they are familiar with certain programs? I would say yes- that may happen.