Year 1 - Firstly we look at how digestive and gas exchange systems may be affected by communicable and non-communicable diseases. How knowledge of basic biology allows us to understand the symptoms of disease and interpret data relating to risk factors. We then move on to look at the influence of genetic and environmental factors on intraspecific variation. How the variety of life is reflected in similarities and differences in its biochemical basis and cellular organisation. How size and metabolic rate affect an organism's requirements and gives rise to adaptations. YEAR 2 -This year we look at how living organisms form ecosystems through which energy is transferred and chemical elements cycled. How human activity affects ecological balance in a variety of ways. How genetic variation and isolation may lead to the formation of new species. We then move on to look at stimulus and responses-the biology of the nervous and endocrine systems, homeostasis and the maintenance of a constant internal environment, genes and genetic expression.