How does temperature affect the fermentation of yeast?

Effect of Temperature on Fermentation Temperature changes have profound effects upon living things. Enzyme-catalyzed reactions are especially sensitive to small changes in temperature. Because of this, the metabolism of a poikilotherm, an organism whose internal body temperature is determined by its environment, is often determined by the surrounding temperature. Bakers who use yeast in their bread making are very aware of this. Yeast is used to leaven bread (make it rise). Yeast leavens bread by fermenting sugar, producing carbon dioxide, CO2, as a waste product. Some of the carbon dioxide is trapped by the dough and forms small “air” pockets that make the bread light. If the yeast is not warmed properly, it will not be of much use as a leavening agent; the yeast cells will burn sugar much too slowly. In this experiment, you will watch yeast cells respire (burn sugar) at different temperatures and measure their rates of respiration. Each team will be assigned one temperature by your teacher and will share their results with other class members. You will observe the yeast under anaerobic conditions and monitor the change in air pressure due to carbon dioxide released by the yeast. When yeast burn sugar under anaerobic conditions, ethanol (ethyl alcohol) and carbon dioxide are released as shown by the following equation: C6H12O6 2 CH←→⎯3CH2OH + 2 CO2 + energy glucose ethanol carbon dioxide Thus, the metabolic activity of yeast may be measured by monitoring the pressure of gas in the test tube. If the yeast were to respire aerobically, there would be no change in the pressure of gas in the test tube, because oxygen gas would be consumed at the same rate as carbon dioxide is produced

First, there is a problem with how the question is phrased. The yeast does not itself ferment. It causes the fermentation of the substrate (sugar water) Temperature has an exponential effect on this biological reaction and others such as bacteria growth, similar to the effect of temperature on chemical reactions which is governed by Arrhenius's law (forgive the misspelling). I don't know what the biological equivalent of this law is called. This happens up to the point when the increasing temperature adversely affects the health of the yeast, causing fermentation to slow. Therefore a curve of fermentation rate versus temperature would rise, then fall.

Yeast brings about fermentation by secreting certain enzymes (like zymase or invertase) and enzymes have an optimum temperature or a temperature range which is essential for them to take effect. For example, when the temperature of your body rises, i.e., in fever like conditions, you lose your appetite and the enzymes aren't as effective as they are at normal body temperature.

because yeast is alive. it's like any other living thing. if it's cold, its moves slower and if it is warm it will move faster. unless it is to hot in which case it dies