Question: I placed some diastase powder (a starch-digesting enzyme) in some starch solution in a test- tube. By taking samples from the tube and testing them with iodine, I found that the starch gradually disappeared. I repeated the experiment but added a few cubic centi-metres of dilute sodium carbonate (an alkali) to the starch solution before adding the diastase. The starch took longer to disappear. I concluded that diastase had an optimum pH of 7 (neutral).
Critique (a) the student's experimental design (as judged by the report), (b) the student's
interpretation of the results.( no more then 7 sentences, simple not over the top)