EDEXCEL MARKSCHEMES

Bro edexcel markschemes are scaring me to death whenever I solve AS bio past papers for unit-1, the answers are so fking SPECIFIC and UNPREDICTABLE in the ms and my answers arent there even if its correct on some previous year's ms, also I solved all papers 2018-2024 and like only 0.01% of questions are repeated, now I think Im failing Alevels after getting a 9 in cambridge IGCSE.

For anyone who sat edexcel alevels (especially Biology) before, how are the grade boundaries? are the examiners lenient with marking or applying this strict nightmare markschemes? how do I predict the answers in the MS?