FRQ rubrics are part-based. Each lettered part (a, b, c...) is worth a set number of points, and you earn or lose points part by part, not holistically. A weak answer to part (a) does not hurt your score on part (b). For long FRQs, graphing parts have specific rules: label axes with units, plot all data points, draw an appropriate best-fit line or curve, and include a title. For all FRQs, the command word tells you exactly what the rubric expects.
Write a one-sentence 'explain' response for a process you know well (e.g., why increasing substrate concentration increases enzyme activity up to a point). Check that your sentence names the mechanism, not just the outcome.