Experimental reasoning
Hold relevant conditions constant, use independent biological replicates, and define the response operationally. A respiration chamber may measure oxygen consumption or carbon dioxide production; these are related but not identical assays. Floating leaf disks reflect net oxygen accumulation and are influenced by both photosynthesis and respiration. Data support claims within the tested conditions. Error bars describe uncertainty or variation as defined in the legend; overlap alone is not a universal significance test.
Compare catalase rates at several temperatures using equal enzyme and substrate concentrations, recording initial oxygen production per minute.
A plateau is not evidence that an enzyme has stopped: a constant maximum rate still makes product.