Cellular Respiration Lab

Purpose: To understand how different factors such as temperature affect the rate of cellular respiration.

Materials: yeast, apple cider, 3 125mL flasks, 3 balloons, masking tape, triple beam balance, graduated cylinder and ruler

Procedures:

1.  Label flasks 1, 2 and 3.

2.  Measure and place 120 mL of warm cider in flask #1.

3.  Measure and place 120 mL of cold cider in flask #2.

4.  Measure and place 120 mL of room temperature cider in flask #3.

5.  Measure and place 5 grams of yeast in each of the flasks. Place yeast in flask one at a time and immediately place the balloon over top and tape it before adding yeast to the next flask.

6.  Record your initial observations of the solutions.

7.  At each 2 minute interval, use a ruler or tape measure to get the diameter of the balloon for each of the flasks.

8.  Observe the reaction for at least 30 minutes (longer if you have time).

9.  Pour the cider solutions down the sink. Remove the balloons and tape and throw them away. Clean the flasks and place them in the drying pan. Be sure your lab station is clean.

10. Record your results on the data table and use the graph provided to graph your data.

11. Answer the analysis questions on your paper.

Name: ______

Diameter ( cm)

Time / Flask #1 / Flask #2 / Flask #3
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30

Conclusion:
1.) Did the balloons change in circumference during the period of this experiment?
If so, which balloons changed the most? What is causing the change in balloons?


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?


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 enzyme function.