A machine, not a person, will score your SAT II Biology Test. The tabulating machine sees only the filled-in ovals on your answer sheet and does not care how you came to these answers; it just impassively notes whether your answers are correct. So whether you knew the correct answer right away or just took a lucky guess, the machine will award you one point. It doesn’t award points if you managed to get a tricky question right. Think of this scoring system as a message to you from ETS: “We care only about your answers, not any of the thought behind them.”
So you should give ETS right answers, as many as possible, using whatever means possible. The SAT II Biology Test not only allows you to show off your knowledge of biology, it gives you the opportunity to show off your foxlike cunning by figuring out what strategies will allow you to best display that knowledge.
Use of calculator is not important to discuss on biology test. Biology is a theoratical subject which relies on concepts. Your preparation must focus the learning and less in practicing.