I'm really scared about taking biology in high school?

Your concerns and worry are understandable. Please do talk with your parents about how taking a "regular" biology class gives you some anxiety. Just an fyi that even if a student with a disability is in a "regular" class, he/she would still qualify for classroom accommodations, according to the Americans with Disabilities Act (ADA) of 1990. For instance, the ADA guidelines should allow the students with disabilities to get additional time on exams and/or a separate room for tests (such as if decreased focusing and attention span are an issue).

Documentation of the student's disability(ies) is usually needed for the teacher to grant those accommodations, but it shouldn't be a problem. For students who are having difficult getting support from any department in the school system, a "special education advocate" may provide some assistance.

I'm just presuming that the fact that you used to be in special education classes may allow you to switch back more easily. Please keep communication with your parents open so that they can give their input to the Child Study Team (who "classifies" students with a learning or emotional disorder), if need be, as to your classroom placement. High school is supposed to be as positive as it should be for the students :)

Please remember to keep up with the reading assignments of your textbook or any materials handed out from the teacher. It's better to read every night rather than studying and cramming for a test. Perhaps the school also has tutoring for students as well, such as from those in the "national honor society" who are doing their community service.

If this is now required to graduate, you would have to take it--having moved out of special education classes. The school cannot waive it.

Break down the assignments so you can keep up with materials--especially where you have trouble with assignments more easily. Write down everything the moment you get it. Don't delay. Ask the teacher to clarify difficult issues/concepts--which they can and will do in high school. They can also provide one on one tutoring.

I was in the same boat and I ended up not taking a harder class. Years later i regret it and I really Recommend it. Trust me, I Really want you to not worry about other people and worry about you and education. Its very important!