Don't worry about your previous examination - you can't do anything about it - try and focus on your next one instead.
It's all a matter of positive attitude. Remember, this is your chance to produce the very best work you can on this topic. It's worth taking up the challenge to prove what you can do - after all, it will be over in a few hours.
Good luck, and remember, if you have any concerns about your revision, exam preparation or the exam itself - your teachers are there to help you.
If you should be unlucky with any of your examinations, your teachers or Examinations Officer will give you advice about resitting and having another opportunity to pass or improve your performance.
If you believe that one of your exams should have been graded higher, speak to your teacher in the first instance. If they support your decision they may apply for a re-mark. Here are some Frequently Asked Questions (FAQs) about results enquiries that may help you to understand the process.
Get past papers (or practice papers) and mark schemes for other exams here.