That's not how it works for grad schools. The GRE is barely weighted, if at all. You just need to score above a certain threshold. Grad schools look at GPA and research experience - i.e., what can this guy bring to us? Because for science majors you should absolutely not be paying for school, you represent an investment and the school wants to know they'll get their money's worth.
In the real world science majors can't get any good science jobs without a master's degree at the very least. Employers do care very much, unless you just want to be a lab tech for the rest of your career.