BIO HELP!!?

I have a test on cellular respiration in 2 days in my honors bio class. The tests are super hard and ask very obscure questions that requires u to rly apply everything that u learned. I understand it, but I don t really get the big picture. If someone who s good at this topic could plz explain it in key points and summarize it, that would be amazing. I ve been studying for hours but I still feel like I m not rly grasping it. Thank u!