The OCR GCSE Biology Paper 3 (June 2021) explores core biological processes including photosynthesis, cellular respiration, and enzyme activity. It emphasizes the role of hormones in plant and human systems, such as ethene, FSH, and thyroxine. Investigations include transpiration, lipid digestion, and protein synthesis. Key topics include DNA structure, menstrual cycle regulation, and xylem function. Practical applications focus on data analysis and experimental design, with ethical considerations in stem cell research and hormone replacement therapy. Genetic concepts, such as the triplet code and RNA variations, are integrated to explain protein synthesis and differentiation.