How do I answer a long answer question in detail without writing too much and wasting exam time?

Use key words and ensure you are specific in what you are saying. Try and avoid writing in long sentences, use bullet points if you can. Diagrams are also helpful for the examiner to understand your answer better. You are also awarded marks for clearly annotated diagrams.

If the question is asking you for a two part answer i.e. describing two processes such as 'Describe how a nucleotide base sequence in a gene is used to synthesise a polypeptide'. Describe process 1 first i.e. translation then describe process two i.e. transcription. Make it clear & easy for the examiner to award you marks.