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. 0.04 ml/min
3. 0.8 ml/min
4. 0.8 ml/min
5. 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.
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