Mathematics pays more attention to logical thinking and reasoning, and needs strong computing ability.

The knowledge of biochemistry is fragmentary and complicated, which requires more expressive ability and memory.

My suggestion is:

Give priority to what you are good at, because some people are particularly strange, but they are better at what they don't like.

If the two are similar, or you really like a subject (so much that you are willing to study it wholeheartedly), then I suggest you choose your favorite subject.

In addition, it depends on your undergraduate study and the major you plan to take.

I am a graduate student admitted this year, and I took Math 2.

Welcome to ask questions or adopt them as answers.