It's a common misconception that only students who don't study A-level maths struggle with the mathematical questions in biology exams. In reality, I often receive queries on how to handle these questions from students who study maths as well as those who don't pursue other STEM subjects.
For both groups, the initial approach is the same. Regardless of the exam board, there's a list of mathematical requirements detailed in the exam specification. The first step is to consult your specification, accessible via each exam board's website. Once there, locate the section on maths. It's usually consolidated in one section, but sometimes it's interspersed throughout, so a thorough examination is necessary. Be prepared to use any formula or equation listed in the specification.
At times, memorization of a formula or equation is necessary; other times, it's provided within the exam question. Unless it's clearly stated that memorization isn't required, assume you need to learn it. Comprehension of the equation is just the beginning; understanding its application, particularly the context in which it's used, is crucial. Seek explanations from your biology tutor on the scenarios where the equation might apply.
The final step is to practice applying these equations in new situations. Request exam questions from your tutor for practice. However, merely practicing questions when you know the required equations or methods isn't sufficient. It's also essential to work on a variety of questions where the required methods aren't pre-determined. The key is application. Grasping the overarching concepts of each biology topic is imperative to then understand the mathematical skills required.