The Investigating the action of the enzyme catalase
...always controlled the main variables. I always viewed the amount of oxygen being collected. I also made sure that I standardised how much oxygen had been collected fairly every time. I also made sure that I stood the same distance away from the experiment to make it fair on all the experiments when I had to standardise the amount of oxygen collected. I always repeated the experiment in the same conical flask so therefore; every experiment I lead had the conical flask of the same width making it fair on every experiment. I also made sure that the measuring cylinder was clear every time so that I could read clearly the amount of oxygen that had been released. I also, used the same tube so that the thickness of the tube was always the same because if a tube is thicker, it can lead to more oxygen being collected because the thicker tube allows more oxygen to pass through. Therefore, to make it fair I always made sure that I kept the same tube. I also made sure that the beaker that I measured the hydrogen peroxide in was clear so that I could see that 50 ml of hydrogen peroxide was always being used. I also used water when I was collecting the evidence so that the pH of the substances used in the experiment did not affect the catalase enzyme, which could change the amount of oxygen collected. Also, I always made sure that each cube was cut into a shape of a proper cube and was 6cm3. Each cube was cut into 1cmx1cmx6cm, the surface area equalling 6cm3 so that it was fair on every experiment. I made sure that I noted the amount of oxygen collected at the end of the ten minutes so that each time the results were reliable. Controlling these variables allowed me to get reliable results. ANALYSI...