The OCR GCSE Biology Paper 4 (June 2023) examines ecological systems, genetic inheritance, and biotechnology. Key topics include biomass loss, Mendelian genetics, decomposition, and human impacts on ecosystems. Practical investigations focus on sampling techniques, aquaculture, and genetic engineering in Atlantic salmon. The paper explores genetic disorders, conservation challenges, and ecological principles like biodiversity and energy transfer in food chains. Ethical considerations in genetic modification and sustainable resource management are addressed. Data interpretation, experimental methods, and real-world applications in agriculture and conservation are central themes.