How Does Various Amounts of Sugar Affect the Yeast Population in 24 Hours?

Kevin Schulze

2/28/2011

IB SL Biology

Mr. McGuire

Introduction

Yeast is a unicellular organism and some of them are used for the making of. Fermentative yeast use sugars and convert them into carbon dioxide and alcohol to produce and create energy. With this energy they reproduce themselves asexually, and so the yeast population consists of both life and death, just like our population.

Objective

The objective of this experiment is to see the relationship between population and food, in this case, sugar.

Research Question

I will investigate how each amount of sugar relatively changes the yeast population in 24 hours.

Hypothesis

My hypothesis is that the yeast population will increase as the amount of sugar increases because reproduction will require energy and sugar is energy for the yeast. However, there will be a point where it hits the limit, as you can see on a S-Curve graph, and so there will be a point where it doesn’t increase as much.

Variables

Independent Variables

The independent variable in this experiment was the amount of sugar, used as the food energy of the yeast population. The different amounts of sugar that will be used in this experiment will be, 0g, 1g, 2g, 3g, 4g and 5g. This is the independent variable because this is the variable that will be altered, while the others will be controlled.

Dependent Variables

The dependent variable in this experiment was the yeast population. This will be recorded through the observations through the microscope. This is the dependent variable because it depends on the independent variable, as sugar affects the yeast population.

Constant Variable

To ensure that the outcomes and occurred only because of the independent variables and not other factors, a set of variables were controlled and kept constant throughout the whole experiment.

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Amount of Water: It is known that it is important to keep the concentration of yeast and sugar the same, as they are the two main factors in this experiment. We will have different results if we did not have constant amounts of water for each. So especially when I was dealing with those two main factors I kept the amount the same, and we used distilled water just so that we will have the best results we can get.

Temperature: The temperature was another factor that was important to this experiment that may have affected ...

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