The following essay appeared on the 1990 AP Biology
examination. Students are advised to either complete the lab
or the cell
respiration simulation before attempting this essay.
The results below are measurements of cumulative oxygen consumption by
germinating and dry seeds. Gas volume measurements were corrected for changes in
temperature and pressure.
Cumulative Oxygen Consumed (mL)/Peas at Different Temperatures
| Time (minutes) | 0 | 10 | 20 | 30 | 40 |
| Germinating seeds 22 C | 0.0 | 8.8 | 16.0 | 23.7 | 32.0 |
| Dry Seeds (nongerminating) 22 C | 0.0 | 0.2 | 0.1 | 0.0 | 0.1 |
| Germinating Seeds 10 C | 0.0 | 2.9 | 6.2 | 9.4 | 12.5 |
| Dry Seeds (nongerminating) 10 C | 0.0 | 0.0 | 0.2 | 0.1 | 0.2 |
a. Using the graph paper
provided, plot the results for the germinating seeds at 22 C and 10 C.
Link to graph
paper
b. Calculate the rate of oxygen consumption for the germinating seeds at
22 C,
using the time interval between 10 and 20 minutes.
c. Account for the
differences in oxygen consumption observed between:
-- germinating seeds at 22
C and at 10 C
-- germinating seeds and dry seeds.
d. Describe the essential
features of an experimental apparatus that could be used to measure oxygen
consumption by a small organism. At minimum, each of the features labeled in the
respirometer pictured at http://www.ekcsk12.org/science/apbio/cricketrespiration.jpg
should be discussed.
Explain why each of these features is
necessary.
