Biology Class Cuts

So I’m taking A-Level biology at my school and there are currently two year 12 Biology classes. We have been at the school for a week and it has now been decided by the SLT that the classes need to be reduced to one class. We are going to have a test on Friday covering the whole of Module 2 (which we so far have had 1 lesson on) and the people who ‘do badly’ on this test will be removed from the course. To me it seems incredibly unfair that people will have qualified for this course, applied, been accepted, done two weeks of school to then just be removed from the course because you don’t want two classes. Can they even do this?