Yeast Respiration Lab

Problem:

Will yeast placed in an enclosed environment with nutrient carry on cellular respiration?
What evidences may be observed to indicate that cellular respiration occurs?

Hypothesis:

If yeast is an organism then it will carry on cellular respiration.

Materials:

50 mL Erlenmeyer Flask, 2/3 teaspoon yeast, 40 mL apple cider, Latex balloon, Spoon

Procedure:

1.) Place 2/3 teaspoon of yeast in Erlenmeyer Flask, by filling a spoon to the point where the yeast is about level with the top of the spoon.
2.) Add 40 mL of apple cider to the 50 mL Erlenmeyer Flask.
3.) Cover the flask tightly with a balloon
4.) Observe and make predictions.  
5.)  24, 48, and 72 hours after setting up the experiment.

Results:

Conclusion:  

1.)   Did the balloons change in circumference during the period of this experiment?
       If so, how did they change?   What specifically accounted for the changes if they
       occurred in this experiment?

2.)  Yeast is a facultative anaerobe.   What does this mean?

3.)  What was the specific source of energy in the apple juice the yeast used
       for respiration?

4.)   The yeast began its respiration aerobically, but then after time completed
       it anaerobically.  How do these two processes differ in terms of the products
       and energy yielded in this process?    List several ways in which the two
       respiration processes are similar?

5.)  How did the physical evidence collected in this investigation support the
      hypothesis that yeast carry on respiration?

6.)  How would changes in room temperature influence this investigation?   Explain why in terms of your knowledge of reaction rates and respiratory enzyme function.

7.)  List and explain at least two major sources of error in this investigation.