This AQA AS Biology exam covers a broad range of topics, including enzyme action, cellular processes, and genetics. Key subjects include DNA structure and replication, the role of enzymes like DNA helicase and polymerase, and the differences between ATP and nucleotides. It also addresses experimental design, such as testing the effect of disinfectants on bacterial growth, and the physiological processes in plants and animals, like lipid absorption and heart function. The paper includes analysis of data, understanding biological systems, and explaining processes like meiosis, crossing over, and the effects of drugs on mitochondrial replication.