How should I behave when my undergraduate research marks reduce without any reason in the evaluation process?
One of the first things I tell my graduate students is:


  Let me know when there's a problem, not a crisis.


If you talk to your advisor now and let her know about the developing situation, she might be able to intervene and help you before the end of the process. 

If you do nothing, and just hope for the best, you may find yourself in a situation where your advisor can't really help. (For example, if you are officially assigned a bad grade, it may be too late for her to do anything.