Physics is a little more difficult than chemistry because it is more mathematically oriented and has more abstract concepts. Chemistry is more difficult than biology because it requires critical thinking to solve complex problems. Chemistry is also more difficult than biology because it requires more mathematics and calculations to explain solutions to problems. If you have a solid knowledge of physics and have a good memory, biology classes are probably not very difficult for you.
If you're still in high school, I suggest you study the most complex subjects in biology, physics and chemistry you can.
