Are tests biased?

Yes, of course they are. No matter how hard an examiner, whether a person or an organisation, tries to be unbiased there will always be some bias.
Scott H Young provides a useful Study Tip at lifehack.org which starts off by saying that "Life isn’t fair. Why should tests be?" He then goes on to provide detailed information about:

• Testing Bias -- what is it?
• What to Look Out For
  Memorization versus understanding
  Narrow versus broad
  Agreement versus quality
  Know the difference
  Average versus extreme
  Hinting versus tricking
• How to Find a Testing Bias by:
  Looking at past tests and course outlines
  Talking to past students
  Asking your professor (tutor/lecturer)
• Don’t Obsess About Testing Bias, But Don’t Ignore It

Scott Young is a university student who writes about productivity, habits and self-improvement. Scott has been featured on the Be Happy Dammit! Show.

The related posts are also useful so do please read them and share with students / learners of whatever age.