Cell Respiration Lab

Title: Cell Respiration Lab

Abstract: In this lab, we used yeast, sugar, and salt mixed together to test the factors that affect cellular respiration. Our hypothesis was that temperature influences the rate of cellular respiration and yeast in warm condition would produce more carbon dioxide than those in cold and room temperature. Our result fulfilled the hypothesis that warm conditions produce the most but rejects that the warmer the temperature the most carbon dioxide would be produced. However, during the lab, we could have made some major mistakes that influenced our results.

Introduction: Cellular respiration is the process by which the chemical energy of "food" molecules is released and partially captured in the form of ATP. Cellular respiration is a chemical process in which the bonds of food molecules and oxygen molecules are broken and new compounds are ormed that can transport energy to muscles. Cellular respiration also releases the energy needed to maintain body temperature despite ongoing energy transfer to the surrounding environment. Carbohydrates, fats, and proteins can all be used as fuels in cellular respiration, but glucose is most commonly used as an example to examine the reactions and pathways involved. There are four steps in cellular respiration: Glycolysis, oxidative decarboxylation of pyruvate, citric acid cycle, and oxidative phosphorylation. The equation of cellular respiration is : C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 6 H2O(l) + heat

There are certain circumstances that influence the rate of cellular respiration. Sugar concentration, temperature, pH and other factors are all included.

Hypothesis: If we put the yeast in the ice, then the yeast would breathe slowly and produces less carbon dioxide. If we put the yeast in room temperature, the yeast would breathe faster that those in ice but still not very quickly. If we put the yeast to warm/heating condition, the yeast would breathe very fast and produce the greatest amount of carbon dioxide because cellular respiration requires an optimal temperature.

Materials: yeast, sugar, water, salt, pipets, 3 tuberculin syringe, timer, 3 test tubes, a heater, an ice box.



Procedure:

1. First, we put 30 mL of water into each test tube.

2. Then, we put certain amount of yeast, sugar, and salt into each test tube, make sure sugar is being put into the test tubes at the same time.

3. We put one test tube to ice box, one to the heating plate, and one in room temperature.

4. Insert tuberculin syringe to each test tube.

5. Time the time the yeast takes to breathe and record down the reading on the syringe.



Results:
The heating plate produced the most carbon dioxide, the room temperature one didn't move at all, and the ice cold one also produced some, but not as much carbon dioxide compared to the heating plate.
 

Conclusion: In this lab, the yeast on the heating plate produced the most amount of carbon dioxide. The yeast in the ice box and in room temperature produced none. The control of this experiment is 1g of yeast, 1 g of sugar and 2g of salt in a test tube. Two possible sources of errors are 1. We didn’t plug in the syringes tight enough so carbon dioxide escaped into air. 2. When producing one of the test tubes, some sugar was spilled so the initial condition could have been different for each test tube. 2 Constants are the time period we wait each time to take the data and the types of tubes, syringes we used. Our result partially rejects partially fails to reject our hypothesis. The yeast in heating condition did produce the most carbon dioxide; however, the other two test tubes produced no carbon dioxide, which rejects our hypothesis that the room temperature one would produce more than the ice one.