The grading system determines your expected grade and capability of the subjects you can handle. When you recieve your target grade there are two reactions, either they are happy with their grade or mainly most teenagers : a negative thinking of a low target grade (which is called fixed growth which negatively thinks they are failures and are afraid to fail). Many teenagers suffer from amount of stress since they must get a "high grade" (like grade 8 or 9) and because of this they will be sleep deprived (since they are studying at night for study cram), loss of social connections (since they might spend more time somewhere else other with friends) and also mood swings. That alone could damage teenagers well being and health and well as developing depression as : they can't relax more often, if they fail they won't have a future, not going with friends anymore and other factors/reason it could result to it.

The best thing to cope with amount of stress is : talk to your teachers (although it may sound wierd but teachers can help especially if they know about tests as well as you), have a break from all study after every 20 mins (so doing 5 min breaks as a gap of study) as it proves focus on study much more, have fun with your family (it can boost your mood and you can have a wonderful time.), have study sessions with your friends as they can help with subjects/topics you are stuck with.

Grading system may be hard, but with the people you can lean on and trust, it will be a lot easier.