Exchange and transport is a core topic in A-Level Biology that explores how organisms take in essential substances (like oxygen and nutrients) and remove waste products (like carbon dioxide). It covers the principles of surface area to volume ratio, which explains why small organisms can rely on diffusion alone, while larger organisms need specialised exchange surfaces and transport systems. You'll study the structure and function of gas exchange systems in mammals, fish, and insects, as well as the mammalian circulatory system, including the cardiac cycle, blood vessels, and the role of haemoglobin in oxygen transport.

This topic is fundamental because it links cellular respiration and photosynthesis to whole-organism physiology. Understanding exchange and transport helps explain how the body meets metabolic demands, how exercise affects heart rate and ventilation, and why certain diseases (like emphysema or atherosclerosis) disrupt these processes. It also provides a foundation for topics like homeostasis, immunity, and plant transport in later modules.

In the Pearson A-Level, this topic appears in both Year 1 and Year 2, with increasing complexity. You'll need to recall detailed diagrams (e.g., of the heart, alveoli, or fish gills), explain adaptations of exchange surfaces, and interpret data from experiments on factors affecting diffusion or heart rate. Mastering this content is essential for exam success and for understanding how living systems function efficiently.