Biology Revision: How do we tell if a substrate is competitive or non-competitive? Increase concentration of substrate. If rate of reaction increases as substrate increases then the inhibitor used was competitive, if not non-competitive. This is because by adding more substrate you decrease the chance of an enzyme forming an enzyme substrate complex rather than attaching to an inhibitor and not reacting. More substrate= less chance of binding to a competitive inhibitor. Why do we store energy as lipids and not starch? Lipids/ fats release more energy than the same amount of carbohydrate when hydrolysed.