An Investigation to Show the Effects of Changing Temperature in Yeast Respiration

What buret reading should you record when the liquid level is as shown in Figure 2?

Procedure: Measure the volume, mass, length and temperature of a variety of items. Create dilution of sugar water.

· I set up the apparatus as shown in the diagram. I then placed a

Pour the 1.5 g of sugar into the beaker and stir with the stirring rod.

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Sugars are vital to all living organisms. The eukaryotic fungi, yeast, have the ability to use some, but not all sugars as a food source by metabolizing sugar in two ways, aerobically, with the aid of oxygen, or anaerobically, without oxygen. The decomposition reaction that takes place when yeast breaks down the hydrocarbon molecules is called cell respiration. As the aerobic respiration breaks down glucose to form viable ATP, oxygen gas is consumed and carbon dioxide is produced. This lab focuses on studying the rate of cellular respiration of saccharomyces cerevisiae, baker’s yeast, in an aerobic environment with glucose, sucrose, lactose, artificial sweetener, and water as a negative control. A CO2

Rate of Respiration in Yeast Aim: I am going to investigate the rate of respiration of yeast cells in the presence of two different sugar solutions: glucose, sucrose. I will examine the two solutions seeing which one makes the yeast respire faster. I will be able to tell which sugar solution is faster at making the yeast respire by counting the number of bubbles passed through 20cm of water after the yeast and glucose solutions have been mixed. Prediction: I predict that the glucose solution will provide the yeast with a better medium by which it will produce a faster rate of respiration.

There are many processes that are needed to occur to produce something that help organisms live. Cellular respiration and fermentation are two process that are important to the survival of organisms. Cellular respiration is the way cells make ATP, which they need to survive. The process starts with the breaking down of glucose into other compounds that can be used by the cell. However, there are more steps in the process than just cellular respiration and how precise cellular respiration is depends on how much ATP can be taken from food particles in the body (Hill 646). Fermentation is mostly known in the world of beer and wine, but it also produces lactate in organisms. Fermentation is breaking glucose into separate components like water or carbon dioxide, much like that of cellular respiration. N’guessan and some peers did an experiment and they found that after fermentation had stopped, they had over 200 counts of yeast in the beer (N’guess, Brou, Casaregola, Dje 858). Under the

Place the beaker labeled 10oC into the freezer for at least an hour before you start your lab Fill the other 4 of the beakers with 100 ml of water each. Then cut 5 strips of paper towel by 5 by 10. (for each trial) Take the beaker out of the freezer. Using the thermometer measure and record the temperature in your data table.

The purpose of this investigation is to test the effect of different sugar sources on yeast respiration.

2. Add about 20 mL of distilled water and stir the mixture with a glass stirring rod to dissolve the sample. There may be a small amount of insoluble residue. If your sample does not dissolve completely, remove the insoluble material by filtration.

2. Add in the evaporated milk and the sugar and stir it to dissolve the sugar then bring it to

3.Measure and add 0.5g, 1.0g, and 1.5g of sucrose into 3 of the test tubes. Do not add sucrose into the 4th test tube because this will be the control. Lightly shake the test tube to mix the contents together.

Once 5 trials have been completed, continue and repeat steps 1-6 for the other temperatures (15oC, 25oC, 35oC & 45oC).

Once this has happened, you will remove the solution from the saucepan, pour the solution into a container and label that container 20% sugar solution.