I see.

Be positive that you will complete work so that you can get points from it. Get graded on the assignment very well. You know, positive thinking. It can be stressful at times but it's one of the ways to go improving.

About you studying biology, had a B, and you just didn't feel that you want to do it. That's the problem. I think you just have to deal with it. Finish the work completely and get graded well.

Find yourself to the limit of your abilities and from there push yourself over it and you might see how far you really can go.