Plan
The aim of my investigation is to investigate the effect temperature has on the anaerobic respiration in yeast.
The independent variables in my investigation that I could choose to change are the quantity of glucose used, the amount of water used and the temperature of the water.
The dependent variables that I could choose to measure would be the amount of Carbon Dioxide produced, the change in the temperature and the amount of Ethanol produced.
As I have chosen to investigate the effect of temperature, the variable that I am going to change is the temperature of the water, this is the independent variable. The dependent variable that I am going to measure is the amount of Carbon Dioxide produced (in bubbles).
To ensure that my test is fair I will make sure that all the other variables that could influence my experiment are kept the same. I will make sure that
The amount of yeast (1.5g)
The amount of sugar (3g)
The amount of water (50ml)
Are all kept the same. I will also repeat my experiment twice for each temperature and take an average of the results so that my results are more accurate.
Preliminary work
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Peer Reviews
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Quality of writing
This piece is constructed superbly. There isn't any irrelevant information, and the thought process flows well throughout the piece. Technical terms are used when necessary. My only query is that they use the phrase "I think" or "perhaps" quite often - if they have backed their thoughts with evidence (as they have in most cases) their language can be a bit more assertive.
Level of analysis
The level of analysis is strong in this piece. They ably identify the variables which affect the experiment, offering a solution to keep them controlled. In my experience, it would be useful to expand on why these variables will alter the results - this can simply be done by mentioning that the concentration of enzymes will increase the number of collisions, and thus the rate of reaction increases. It was nice to see a discussion of enzyme collision theory - it is vital to discuss what happens at extreme temperatures, and this piece has done so by mentioning denaturing. I find when talking about denaturing it is wise to say that this is irreversible, and the reaction will no longer occur at lower temperatures due to the active site being changed.
Response to question
This piece of coursework provides a comprehensive plan, utilising diagrams well to explain why temperature will affect enzymes. Although this is only a plan, an empty results table would improve this piece by showing clearly how the hypothesis will be tested. The experiment is well described and instructions are clear. My only query is that safety is not addressed: when dealing with hot water, it could be advised to wear safety goggles or be cautious of spillages. Acknowledging this will only strengthen a piece of coursework at GCSE level.