As a very rough guide, a W&M GPA of 3.5 and above with GRE scores in the 90th percentiles in all or most tests makes students very competitive for the top 20 graduate programs in almost any field. A GPA of 3.0-3.5 will make it tougher to get into programs in the top 20 but should be high enough for solid Ph.D. programs. A GPA of 2.5-3.0 is competitive for solid master's programs but less competitive for many Ph.D. programs. A GPA of 2.0-2.5 can get into master’s programs, possibly as a "provisional" student with retention dependent on good performance. These rough guidelines vary from field to field, often with exceptions.
Virtually all graduate programs in biology require test results from the Graduate Record Examination, administered by the Educational Testing Service. The GRE consists of a general test covering verbal reasoning, quantitative reasoning, and analytical writing; and a subject test in biology. “The scores provide common measures for comparing the qualifications of applicants and aid in the evaluation of grades and recommendations” (Educational Testing Service). The GRE general test is offered year-round. The Subject Test in biology is offered three times a year (October, November, April). For details and locations, consult the GRE website.