Enzyme Reaction - Catalase. Aim: To test the reaction of the enzyme catalase in various ph levels.

Review of essay

Rating: 3 star(s)

Response to the question

This experiment is structured well, but it is missing a hypothesis. A hypothesis shows the examiner you are applying scientific knowledge throughout. Something along the lines of: "As the pH levels increase, it is expected that there will be fewer bubbles formed during the experiment". This then allows you to draw upon it within your conclusion and explain it fully in the discussion section. Examiners like to safety taken into consideration, and a more thorough method would've allowed this.

Level of analysis

In scientific experiments, clarity and accuracy is key. Using phrases such as "four test tubes containing about" shows to the examiner that you don't fully understand the significance of a fair test. The results table is good, giving only qualitative responses of what can be seen. There does need to be a column heading, however, above liver and potato such as "Tissue Type". The discussion at the end is average. There is a sound knowledge of enzymes and the factors which affect their rates of reaction, but there isn't a thorough discussion of pH levels. When the experiment is specific, you need to spend time discussing the factor in detail. I would've liked to have seen some discussion of how pH level breaks the bonds which make the active site specific (at GCSE it isn't necessary to discuss which bonds break) and then an enzyme-substrate complex cannot form.

Quality of writing

Examiners are always picky with coursework pieces. In an exam you may get away with "ph levels" but you may be penalised otherwise for not writing it as "pH levels". There are times where the grammar is wrong. Although it isn't as important in scientific pieces of work, there will always be marks for Quality of Written Communication (QWC) so it is key these errors are picked up in a drafting process.