The OCR GCSE Biology Paper 1 (June 2021) covers topics like DNA structure, photosynthesis, cell differentiation, human circulation, and hormonal regulation. Key areas include the reflex arc, blood glucose control, enzyme activity, and osmosis. Investigations emphasize practical skills such as using microscopes, interpreting experimental data, and analyzing the impact of environmental factors on plant processes. The paper explores concepts like the menstrual cycle, Q10 calculation for enzyme reactions, and adaptations in organisms. Data analysis and scientific methods are integral, focusing on both theoretical and applied biology.