lower temperature --> less kinetic energy of enzyme and substrate -->the chance of formation of enzyme-substrate complex decrease -->lower reaction rate(e.g respiration ,reaction that break down harmful substances(H2O2),etc) --> deaths of organisms
hope this can help
its bcuz most enzymes in our body work best at 37 degree celsius . enzyme is a catalyst for metabolic reaction, if we cannot provide the optimum temperature for enzyme,it will slow down the metabolic reaction rate