Why can failure to regulate internal conditions reduce the rate of cell reactions?
Receptors may become enzymes and use up the substrates needed for the reactions.
Effectors may stop all molecules crossing the membranes surrounding the cells.
Coordination centres may convert chemical responses into external environmental changes.
Conditions may move away from the optimum for enzymes controlling the reactions.
40 exam-style questions on AQA GCSE Biology 5.1 Homeostasis, covering 5.1 Homeostasis. Each one has a worked solution and a mark scheme showing where the marks go.