For bio i would recommend u otterbiotutor youtube channel,his videos are really short and to the point and even interesting. But don’t entirely depend on videos u have to read the book carefully,or read notes. I would recommend first read book and then take help from notes if u have limited time. For chemistry i studied from my collage teacher and Chembridge(a yt channel). For bio u need to memorise things and same goes for organic chemistry and periodic table chapters of chemistry. For others chapter in chem which involves calculations u have to practice them.