Well, it sounds like the first thing you need to do is find out what all your bachelor track actually entails, what all you are committed to doing. You should probably find this out from the department, not merely from some student. Could you handle being asked to do vivisections for more than the first year?

If it turns out to be the case that for some of your classes you are required to do vivisections, you should talk to your professors about your concerns, as well as see from your professor if there is any alternatives available to you (I know there are alternatives, but whether they will provide them is another question).

If the professor is not willing to accommodate you, I think you got three options: perform the vivisection; refuse to perform the vivisection out of integrity and gracefully take a ding on your grade; or get the administration involved. (Obviously you can also choose a different major, but I am assuming for our purposes that this is not an option). I don't think you'll have luck with the admins, but you could try. Performing the vivisection I don't think is a real option, nor should it be. Remember, the means are the ends. So, you are left with taking a lower grade and refusing to participate. This is what I would do, probably, if I was put into this tough situation. I can't see the vivisection being worth all that much of your final grade, and in the long run, grades aren't all that important.

But I don't know: don't know all the details, don't know all the options, don't know you. Plus, this is just my first thoughts on the matter. I'd suggest giving yourself some time to think it over.

Good luck