How do I get an A* in biology?

Use the mark schemes. These change very little over the years and were my go to during A levels and GCSEs. Do as many past papers as you can possibly get your hands on and work out what the exam board give marks for. Once you've done your past papers, mark them very carefully - I found that I did this best when going through it with a teacher. You can revise the information as much as you like, but unless you practice answering the questions, you will struggle to get A*s. My teacher always said to me that the marks schemes are you best friend and you must use that to your advantage.