Are you confused of what they're asking for or know what they want but just don't know how to answer it?
Cause I see 3 question in that one question... So If I broke the question down I would see..
What would happen to you if your respiratory system was working at about 90% capacity?
What would happen to you if your respiratory system was working at about 50% capacity?
What would happen to you if your respiratory system was working at about 5% capacity?
I don't know if I helped D: cause I'm assuming you don't know what the questions asking... I hope I helped though~:/