Scientists have been experimenting with different types of alternative energy to reduce the amount of fossil fuel burned. They studied yeast, which convert plant materials into ethanol, a form of alcohol that can be used in automobiles. The experiments were carried out at room temperature. The scientists wondered if more ethanol could be produced at different temperatures.
In general, rate of reaction increases with an increase in temperature (so you may have to change your hypothesis). This is defined by the famous Arrhenius equation:
`k = Ae^[(-E_a)/(RT)]`
where, k is the reaction rate constant, A is prefactor, Ea is the activation energy of the reaction, R is the universal gas constant and T is temperature (in kelvin).
A generalized version of this equation states that rate of chemical reaction doubles for every 10 degree C increase in temperature.
In this case, different amount of ethanol can be produced at different temperature, with higher production at higher temperature and lower generation at lower temperature (within a certain temperature range, governed by the yeast as their preferred range of operation).
The independent variable here is the temperature, which can be varied to determine the changes in ethanol production. The amount of yeast and amount of plant material must be same for both the control group as well as experimental group. The duration of experiment will have to be same as well. Higher production of ethanol with higher temperature will support the hypothesis (that higher production is possible at higher temperature).
Hope this helps.