A possible systematic error in this experiment is the H2O2 which is unstable in atmosphere, and will break down even before enzyme is added. Also another error could be the calibration of measuring cylinder and the concentration of pH. In this practical, there are not so many factors that may be potential sources of systematic errors in the data. Although the accuracy was low because there was a very important error which is the H2O2 because is unstable in atmosphere and can affect dramatically the results. Last, because they for systematic errors are constant there is no improvements except if we increase the trials so we will try to minimize them. We had many significant random errors. First of all, measuring the foam volume at the appropriate time. Significant subjectivity in measuring foam volume, as the height of the foam is often uneven, and the measurement is performed under duress. A major cause for concern on accuracy was the human error in timing 15 seconds, can cause an important error, as the time that we had for 2 minutes to soak the liver in different amounts of pH and 15 seconds to record the height of foam, weren't so accurate because even one second is important for the reaction. The true marker of enzyme efficacy is the rate at which oxygen is produced. However, such equipment was not available, so foam-volume was used as a surrogate marker. This is a poor surrogate marker, as the bubbles form and break idiosyncratically. Furthermore, the measuring of the beef liver it wasn't accurate because is almost impossible to measure a liver 1cm x 1cm x 1cm, so if there is more surface area there will be more collisions so the reaction will accelerate faster. Both the shape and volume of liver is important to the experiment, and both were difficult to control. Another random error could be the liver which is inhomogeneous in its Catalase content and the liver contains many other novel substances that are difficult to control in an experimental context. These may help or hinder the reaction in unpredictable ways. Also, during the experiment we used the same equipment and after rinsing for the next trial, the equipment was still wet. Last, a random error might be parallax, because the eye could be higher or lower from meniscus. The data that collected from the experiment wasn't reasonable for the precision with the result the precision to be low, looking back on experiment they can be improvements. Should instead use accurate timing devices and automated photography at the appropriate time. Also liver is inhomogeneous in its Catalase content, so it would be better if the time for soaking the liver in the pH was more than 2 minutes. Furthermore, measure the liver with the ruler with the best way and standardise the mass. Also we can use potato instead liver, because it could be easier to measure it as a cube 1 cm x 1 cm x 1 cm as potato has catalase as well. It's difficult to control the time but you can improve it being one step ahead, this mean that before you see 15.00 at the stop watch, to tell it to your partner who record the reading so he/she can have time to record it. Moreover, the eyes should be at the level of meniscus so the reading can be right and the equipment should be dried before use it for the next trial. Last if we had time for more trials then we would have more precise average.