b. Research Question
e. Control of Variables
2. Materials & Methods
b. raw data
e. processing data
II. Other Help
errors and uncertainty
I. Research Question
• Rather than an Aim and Hypothesis you need to start your Design practicals with a focused research question. A Design practical has a title that is deliberately vague. You, the student, are expected to come up with the independent variable. Use the independent variable and the dependent variable to phrase your research question. You should also include a brief description of your experiment. Eg. What is the effect of a changing glucose concentration on cell respiration in yeast? Five different concentrations of glucose (0.0 M, 0.25 M, 0.50M, 0.75M and 1M) will be used to see how the growth of yeast changes. The growth of yeast will be measured by the amount of CO2 produced which is an indication of the amount of cell respiration taking place. It is expected that increasing the glucose concentration will increase the amount of C02 produced which will suggest that the rate of cell respiration has increased.
• While a hypothesis isn’t needed and sometimes it’s not possible, usually in biology you will have a hypothesis. If you include a hypothesis to help focus your research question then it needs to be an “if….then…” statement that includes the independent and dependent variables. Your hypothesis should be supported with an explanation. Eg. If the glucose concentration is increased, then the amount of C02 produced will also increase. This is because glucose is used by yeast to make ATP through cellular respiration. The more glucose that is available, the faster the rate of cell respiration, and the more C02 that will be produced. C02 is a product of cell respiration in yeast, so the more C02 the faster the rate of cell respiration. [pic]
• Remember to correctly categorize your variables and think of as many controlled variables as you can. That said, don’t include controlled variables that aren’t significant. For example if you’re measuring the growth of yeast then the temperature definitely needs to be controlled (assuming temperature is not your independent variable) but the same location is not going to be a significant factor. For those who can’t recall or have never learnt how to categorize variables:
Independent: The variable that YOU change.
Dependant: The variable that changes when you change the independent variable (what you measure).
Controlled: All the aspects of the experiment that must be kept constant to ensure that the tests/experiment is fair. There will be several of these not just one! • Make sure that you choose only one independent variable to change. Some people inadvertently choose more than one. [pic]
IV. Control of Variables
• Your must explicitly indicate how each controlled variable identified in your variables section was controlled. If you can’t actively control a variable then your method should include a means of monitoring it. [pic]
• In a Design practical you need to choose the apparatus and submit an equipment request. Make sure you plan thoroughly and don’t leave anything out. If you need something extra that you didn’t put on your list it will be provided but you will receive a partial for the first aspect of this criterion. The same thing applies if you “borrow” from another group. Of course if you try and persist with what you have but I can see that it’s clearly not enough, well that’s a partial too. • Make sure when writing up your equipment list that you...