The OCR GCSE Biology Paper 3 (November 2021) covers core biological principles, including photosynthesis, respiration, and protein synthesis. Topics such as enzyme activity, hormonal regulation, and genetic mutations are explored. Practical investigations include stomatal density analysis, transpiration measurements, and the Q10 effect on enzymatic reactions. Key themes emphasize homeostasis, human physiology, and experimental methods like potometer use and Benedict′s test for glucose. Ethical considerations, data interpretation, and the application of biological concepts in environmental and medical contexts are central to this paper.