Unit 1 Eukaryotic and prokaryotic cells Unit 2 DNA and the genome Unit 3 Health and disease Unit 4 Biological molecules and enzymes Unit 5 Transport and exchange surfaces in humans Unit 6 Coordination and control: the human nervous system Unit 7 Coordination and control: hormones and the human endocrine system Unit 9 Inheritance, genotype and phenotype Unit 10 Cell division: mitosis and meiosis Unit 11 Stem cells and differentiation Unit 12 Fossil evidence, selective breeding and explaining evolution Unit 13 Living organisms and their environments