The OCR GCSE Biology Paper 1 (June 2019) explores key biological principles, including photosynthesis, respiration, and enzyme activity. Topics like genetic engineering, food chains, biodiversity, and reflex actions are emphasized. Practical investigations cover light microscopy, testing food samples for nutrients, and analyzing predator-prey dynamics. The paper also addresses the environmental impacts of deforestation, the role of decomposers in ecosystems, and sustainable practices like selective breeding. Ethical considerations and the application of biological principles in genetic modification and conservation feature prominently.