During Year 12 the course involves the study of four units: Biological molecules, Cells, Organisms exchange substances with their environment, Genetic information, variation and relationships between organisms. During Year 13 a further four units are studied: Energy transfers in and between organisms, How organisms respond to changes in their environment, Genetics, populations, evolution and ecosystems, The control of gene expression. Investigation is at the heart of Biology and a rich diet of practical work is essential to develop students’ manipulative skills and understanding of the processes of scientific investigation. Students taking A Level Biology will be expected to carry out a set of 12 practical activities which will be assessed by their teachers and required for their practical skills endorsement.