Cell Respiration:
Lab Quiz Answers
The accompanying graph shows results from an
experiment done to measure cellular respiration in
germinating and nongerminating corn seeds. On the
basis of the graph, answer questions 1–3.
1. Which of the following is a true statement based on the data?
1. The amount of oxygen consumed by germinating corn at
22oC is approximately twice the amount of oxygen
consumed by germinating corn at 12oC.
2. The rate of oxygen consumption is the same in both
germinating and nongerminating corn during the initial time
period from 0 to 5 minutes.
3. The rate of oxygen consumption in the germinating corn at
12oC at 10 minutes is 0.4 ml O2/minute.
4. The rate of oxygen consumption is higher for
nongerminating corn at 12oC than at 22oC
5. If the experiment were run for 30 minutes, the rate of oxygen
consumption would decrease.
The correct answer is a. Study the graph carefully to see that at 10
minutes the 22oC germinating corn consumed 0.8ml of oxygen,
while the 12oC germinating corn consumed 0.04 ml of oxygen.
2. What is the rate of oxygen consumption in germinating corn at
12oC?
1. 0.08 ml/min
2.
3.
4.
5.
0.04 ml/min
0.8 ml/min
0.8 ml/min
1.00 ml/min
The correct answer is b. To calculate this, it is easiest to find the
change in y at 10 minutes (0.4 ml - 0 ml = 0.4) and divided by the
change in x (10 minutes - 0 minutes = 10 minutes). 0.4 ml/10
minutes = 0.04 ml/min.
3. Which of the following conclusions is supported by the data?
1. The rate of respiration is higher in nongerminating seeds
than in germinating seeds.
2. Nongerminating peas are not alive, and show no difference
in rate of respiration at different temperatures.
3. The rate of respiration in the germinating seeds would have
been higher if the experiment were conducted in sunlight.
4. The rate of respiration increases as the temperature increases
in both germinating and nongerminating seeds.
5. The amount of oxygen consumed could be increased if pea
seeds were substituted for corn seeds.
The correct answer is d. This is the only statement that is supported
by information provided on the graph.
4. What is the role of KOH in this experiment?
1. It serves as an electron donor to promote cellular respiration.
2. As KOH breaks down, the oxygen needed for cellular
respiration is released.
3. It serves as a temporary energy source for the respiring
organism
4. It binds with carbon dioxide to form a solid, preventing CO2
production from affecting gas volume.
5. Its attraction for water will cause water to enter the
respirometer.
The correct answer is d. As carbon dioxide is released, it is removed
from the air in the vial by this precipitation. Since oxygen is being
consumed during cellular respiration, the total gas volume in the vial
decreases. This causes pressure to decrease inside the vial, and water
begins to enter the pipette.