Expert: Walter Hintz - 1/11/2009

Question
In my Biology class we are working on Cellular Respiration and I am having
some trouble. I understand the basic concept, but am stuck on what to do for
my lab. The teacher has posed the question: "What does temperature have to
do with making bread dough rise" (aka how does yeast work and what does it
release)/(what effect does temperature have on cellular respiration). we must
create an experiment to prove this and must then write an essay on it. we are
given the following materials: glass tubing, stoppers, test tubes, flasks,
beakers, ice, hot plates, yeast, vaseline, water, sugar, thermometer, and
anything we feel we need that he approves. I just need help on how i can
probe this, and what EXACTLY is going on... (thanks so much!!)

Answer
Hi nini
Cellular respiration is the metabolic process by which glucose is broken down into water and CO2 with the release of energy.  You problem deals with yeast that completes this through the process of fermentation.  Fermentation occurs in the absence of oxygen and yeast requires warm temperatures.  Bakers yeast releases CO2 during fermentation and the CO2 bubbles cause the dough to rise during the baking.  As the temperature rises the yeast cell are killed.  
 I think that with your experimental design you will have to put yeast and sugar in a beaker and through tubes bubble the CO2 into distilled water. You can test the water for acid (H2CO3)
You can use varying temperatures to show the need for warm temps.
 Read up on fermentation