Wow, I am so sorry. I hope everything will be ok, and you can re-take the test in short order. Please let us know what happens with that. If they looked at your actual exam, you would think they would understand that it was a total error on your part and nothing to do with your ability to pass the test. Biology is a tough one to study for, let alone take as a first exam. I wish you the best. You could look at it as a learning experience, and it will give you a bit more time to study. I know that doesn't help much when you are smacking your head and saying, "Doh!"
