well we did the enzyme, pH/temperature prac a few weeks ago. basically what we did, was set up like 5 test tubes for each part (temp and pH) and put like different levels. e.g. pH1,3,5,7,9 and temperatures of 20,25,30,35,40. we added some chemical(cant remember its name), that reacts with the catalase enzymes in the livers pieces and we took down the results by measuring the hieght of the bubbles generated. Then we made a graoh showing the results and we saw that enzyme optimal efficiency curve(where is goes up gradually, reachs a peak then drops radically as the enzyme denatures). Hope that helps.