For your BP Biology lesson, I would really go to that NERD link that was supplied... Many others have wonderful genetics pages on their websites... but I found NERD's easiest to understand, and very complete.

And as Christie already said... there have been MANY things covered about this already in this forum.. Just read through some of the "Morph" forum posts. You'll find the answers to just about all of your questions I'm sure.

Good luck!