How tf can I stop loosing marks when I know them

Thing is, in the last AIATS and yday's CST, both papers were ez and I knew almost al the qs. But I make the most damn sillest mistakes like not reading properly or sm shit. Like I get 140s in phy in aiats and same for cst's chem. But I'm losing atleast 60-70 marks in bio even even I know it. That makes me who expects around 600s to get in 540s. PLEASE HELP KARO, IM SO TERRIFIED THAT I'LL DO THE SAME SHIT ON MAY 3rd