In this module you will cover:

• Specialised exchange surfaces: The internal environment of a cell or organism differs from its external surroundings. Substances move between these environments through specialised exchange surfaces. To fully enter or exit an organism, most substances must pass through cell plasma membranes. 

You will learn about specialised exchange surfaces including an insects gas exchange system, the fish gills, the leaf and the alveoli in the lungs.

• Tissue fluid: In large multicellular organisms, individual cells are surrounded by tissue fluid, which serves as their immediate environment. 

• Transport systems: Due to the distance between most cells and exchange surfaces, simple diffusion alone is insufficient to maintain optimal tissue fluid composition for metabolism. Instead, large organisms rely on mass transport systems to transport substances between exchange surfaces and different parts of the body.

You will learn about the heart and the circulatory system as a mass transport system in animals.

You will also learn about mass transport systems in plants - including the transport of water and mineral ions in the xylem and the transport of sucrose in the phloem.