12.1 Uses of energy and respiration

Why living organisms need energy — the seven Cambridge uses (muscle contraction, protein synthesis, cell division, active transport, growth, nerve impulses, body temperature) — and the practical investigation of how temperature affects respiration rate in yeast (using a hydrogencarbonate indicator + water bath at varied temperatures, with a rate-vs-temperature curve showing the optimum near body temperature and enzyme denaturation above ~50 °C).