Problem: The Research Question should not just be a repeat of the general problem provided by the teacher. Rather, the Research Question should indicate what specific aspect of the general problem you will be investigating.

The Research Question is: “does temperature affect the rate of anaerobic cellular respiration in yeast?”. We will be investigating how different temperatures affect the rate of fermentation of yeast. The experiments will help give us some information with real-life situations where anaerobic respiration is present, and how we can avoid certain unwanted results (e.g. cramps from exercising without breathing enough).

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Background: Provide scientific background about the problem you are trying to solve. Specifically, this is the theory one should know to understand the experiment. Be sure to cite the sources that were used in the research portion of the introduction.

Cells use cellular respiration to transfer energy from food to ATP. ATP is an energy source for cellular processes. When there is not enough oxygen available to carry out cellular respiration, the cells will switch to anaerobic respiration (fermentation), where the cells produce lactate (lactic acid), carbon dioxide, and ethanol (alcohol). Instead of breaking molecules from glucose, cells will use fermentation instead. Anaerobic respiration produces less ATP than aerobic respiration. Anaerobic respiration still produces energy using glucose, but does not require oxygen. Because yeast has the capability of breaking down sugars into glucose, it produces carbon dioxide. Due to the production of carbon dioxide, we will be using the balloon on the test tube as a sign of how much carbon dioxide has been production. In this experiment, we will be looking at fermentation, particularly in yeast, using sucrose.

Sources: “What is the difference between aerobic and anaerobic respiration ….” Accessed 11 Sep. 2018.
“The Effect of Temperature on the Rate of Yeast Respiration Essay ….” Accessed 13 Sep. 2018.

Hypothesis : A prediction of what you think will happen in the experiment. This prediction is written as a testable statement or question directly related to the Research Question about what you think is going to happen when you measure one variable and you change another. This statement must be quantified and include a prediction. It must specifically predict what will be observed in the data if the independent variable causes an effect.

I think that cooler temperatures will increase the rate of respiration in yeast because the molecules will move so fast to the point where the yeast cannot respire. When you measure one variable, such as the size of the balloon and change another, in this case the temperature of the water, the results will be altered (the rate of the respiration will increase).

Explain your hypothesis using scientific language:

Independent Variable: The independent variable is the variable that the experimenter controls or manipulates. It is the variable that causes the response or reaction in the experiment.

Explain how this will be measured:

The independent variable is the temperature of the water, and it will be measured in degrees Celsius or degrees Fahrenheit.

Dependent Variable: The dependent variable is the variable that is influenced by the independent variable. It is what is being measured or the data that is being collected.

Explain how this will be measured:

The dependent variable will be the rate of anaerobic respiration in the yeast. This will be measured by the size of the balloon, by recording the diameter and height of the balloon.

Controlled Variables: Controlled variables are the items in the procedure that must be kept constant from trial to trial to make sure that the data collected is only affected by the independent variable. Identify at least 3 most significant variables that if not held constant could alter the dependent variable.

The amount of yeast
The amount of yeast will directly affect the outcome of the experiment because the more yeast there is, the more effective they will be in carrying out anaerobic respiration.

The amount of sugar water
The amount of sugar water will change the results of the experiment because the glucose in the sugar water will alter the rate of anaerobic respiration.

The time waited for the yeast to anaerobically respire to collect quantitative and qualitative observation
The time waited for the yeast to anaerobically respire will alter the results because the yeast will be in different stages of anaerobic respiration, and if there is more time given, the results between trials will not be even, and will have drastic differences between them.