This course explores the challenges faced by organisms that result from living in changing and extreme conditions. It provides an overview of physiological and biochemical responses and adaptations, to deal with such circumstances. Physical factors that are considered are changing temperatures, changing O2 and CO2 levels, changing pH, and water availability. Responses and adaptations in a broad range of physiological and biochemical processes are discussed. These include, for example, metabolism and defence systems in animal systems under environmental pressure, and, for plants photosynthesis, primary metabolism, growth and defence responses.