The OCR GCSE Biology Paper 4 (November 2020) explores ecosystem dynamics, genetic inheritance, and the impact of human activities on biodiversity. Key topics include the water cycle, natural selection, antibiotic resistance, and composting methods. It highlights practical investigations, such as measuring bacterial resistance, analyzing food webs, and calculating changes in compost mass. Concepts of gene mutations, selective breeding, and phylogenetics are examined alongside their ethical implications. The paper emphasizes scientific inquiry, data analysis, and the application of biological principles in conservation and agriculture.