You remind me a lot of myself when I was your age, that's the why I'm replying.
Why must we go to school? Spend time with biology? There's a million reasons. One of the reasons why you take classes such as earth science, physics, biology, and chemistry is to train your brain to think logically, and scientifically. When you're this age, your brain is STILL NOT USED TO thinking this way. In no way shape or form, do they even try to make you a biologist... believe me.... high school biology is NOTHING like real biology used in all the biological fields. It's just the icing - the very basics - so you get a feel for what it is. If you think a year is too much... take the time to consider how BIG the field is. Do you think someone becomes a doctor by studying for a year? Two? Doctors never stop. They must always be up to date with the latest treatments, etc.
You say that if a person who knows what they want to do, should start studying it. I agree with you. But how can you start if you don't know what else is there? You don't know your options. That's like me saying I tried ASP, and I really liked it, and I then ignore all the other languages just because I "THINK" I like ASP. Yes, they should start studying it... in college.
All this is in an educational sense. We must also not forget the way an early to middle-adolescent thinks vs a late-adol to early adult thinks. The thought process is very different in the maturity level. In HS you don't worry about paying bills, paying for an appartment, getting married, and other issues like that. This is another teaching process in itself.
Don't get me wrong, I felt the same way when I was your age. I would say to myself, "I know what I want to do. I want to do art and music. Why on earth should I take calc, physics, and all these classes if it has nothing to do with what I want to do! It's a bunch of BS! Why must I get changed in Gym?!" =) And now look, I took a computer course, I liked it, and now I've found a carreer where I can integrate music + art + programming all into one -> web development.
Personally, and don't take this the wrong way, I'm glad I don't think like that anymore. Just think of it this way, people that have gone through what you're going right now have been able to create all the high tech stuff that's around you. We owe it to these "stupid" classes.
It's like eating vegetables. It's good for you, but it doesn't mean you have to like them.