revising for biology the night before year 10 unit 1

im actually sooo stressed about this, especially because im not the brightest in biology, yet i was entered for higher tier, i really hope to achieve atleats a C, however heres the problem.

when mocks were introduced for science, i did the biology mock and came out with a D, thats because my studying wasnt efficient enough and i didnt have the right materials and was unaware of advanced details given about the mock, and i didnt even know where to begin to revise, i just rewrote everything in my biology book and tried to memorise it the night before, which is probably why i preformed poorly.

however now i've received advanced information about my exam that im going to be doing TMR... i have less than 24 hours to revise and im so anxious, however this time i've come more prepared with my notes since i know what im prioritizing to revise, i feel like i could do it but i just dont know, im just really scared but i hope i achieve atleast a C/B, i think i will spend all of tomorrow memorizing my stuff and then testing it out on past papers and during my actual exam i'll spill everything i crammed into my head on the back of the paper so i can flick back to that part of the exam paper just incase i forget info halfway thru doing the exam paper and it was needed for a question, I THINK THATS A GOOD plan??? im just worried because theres 30 pages worth of notes, and some parts of it , i just dont understand so i rely on memorizing which is a bad thing i know since the only way of doing well is from being able to understand what you're doing, but i js dont get some of it ahhhhhh

the topics btw.. are

1. ecosystem and human impact
2. cells and movement across membranes
3. circulatory system
4. photosynthesis in plants
5. respiration
6. digestion/digestive system and enzymes

im actually terrified , wish me luck....