我现在大一，刚入学想4年后上美国康奈尔研究生，请问应该考什么？什么时候考？复习计划的提供下！谢谢!

You have a very clear and detailed goal ahead!
First thing you need to do is hard-working in your major to gain a top GPA at least over 3.5 ,however 3.6 or 3.8 doesn't make a big difference except that you wanna a fellowship.You should then devote your energy left all to the researching background build-up about your major,namely,biology.A paper or two might contribute a lot to your future application for the Cornell.Finally, the GT thing, you must remember GPA is first and GT scores are the second.
Usually GT preparation starts in the summer before junior year or later which depends on one's English levels and time availability.If you're confident in your English capability enough, all right, you may take the GRE first.Otherwise starting with IBT will be a wise choice.And remeber to finish the GT tests before senior year cos the senior year is for application.
You will surely have two very busy years in the years to come.Wish you a bright and successful f