ON 'GENE INTERACTION'

Practice, practice, practice!
Chapter 6 is full of good questions (try 64and 65). Also, there are a lot of loppins questions that you should be able to do-click on the link and have a look at #1, 2, 3, 4, 6 and 8.

Remember that for this kind of problems you'll sometimes need to use your intuition and/or a trial and error approach...