Biology: Cellular Respiration

As noted earlier, the amount of water that enters the pipette is directly proportional to the amount of oxygen consumed by the germinating peas. Therefore, by measuring movement of water into the pipette, you can determine the rate of cellular respiration--typically measured as oxygen consumed in milliliters per minute (mL/min). Water in a pipette adheres to the side of the tube and forms a curved surface called a meniscus. By common practice, all readings are made at the bottom of the meniscus. Examine the following figure. What is the reading in the pipette to the nearest 0.01 mL?

0.25 mL

When conducting an experiment to compare the rate of respiration in germinating peas at two different temperatures--12 C and 22 C--what would be a good control for this experiment? A vial with an equal volume of glass beads A vial with an equal volume of nongerminating peas A vial without any peasA vial held at room temperature

A vial with an equal volume of nongerminating peas

If you had a sample organism and wanted to measure its rate of cellular respiration, which of the following methods would provide useful information? Study the equation for cellular respiration to have a clear sense of what is consumed and what is produced before answering the question. Select all that apply. Measure the amount of carbon dioxide consumed. Measure the amount of glucose produced. Measure the amount of oxygen produced. Measure the amount of carbon dioxide produced.Measure the amount of oxygen consumed. Measure the amount of glucose consumed.

Measure the amount of carbon dioxide produced. Measure the amount of oxygen consumed. Measure the amount of glucose consumed.

Using the equation for cellular respiration as a guide, sort the following items depending on whether they are the reactants or products of cellular respiration. (Try to do this without looking back! This is one equation you should have memorized.)

Reactants: C6H12O6, O2 Products: CO2, Energy, H2O

Another technique for collecting data to measure the rate of cellular respiration involves placing the study organism into a closed chamber with a probe inserted, to measure the concentration of either O2 or CO2. Most probe systems allow for rapid collection of data combined with programs to graph the results. Consider an experiment in which CO2 sensor probes are inserted into two chambers: Chamber A keeps organisms at 10∘∘ C. Chamber B keeps organisms at 25∘∘ C. What results would you expect? The organisms in chamber A would show greater activity than those in chamber B. The level of CO2 would increase more rapidly in chamber B than in chamber A. The organisms in chamber B would show evidence of CO2 toxicity. The level of O2 would decrease in chamber B more rapidly than in chamber A.

The level of CO2 would increase more rapidly in chamber B than in chamber A.

Which of the following conclusions is supported by the data shown in the graph? Which of the following conclusions is supported by the data shown in the graph? The millileters of oxygen consumed over time in cellular respiration in germinating peas would have been higher if the experiment were conducted in sunlight. The millileters of oxygen consumed over time in cellular respiration increases as the temperature increases in both germinating and nongerminating peas. The millileters of oxygen consumed over time in cellular respiration is higher in nongerminating peas than in germinating peas. Nongerminating peas are not alive and show no difference in the millileters of oxygen consumed over time in cellular respiration at different temperatures.

The millileters of oxygen consumed over time in cellular respiration increases as the temperature increases in both germinating and nongerminating peas.

What difference, if any, would you expect in the rate of cellular respiration in the germinating peas in vial #1 compared to the nongerminating peas in vial #2? The nongerminating and germinating peas will show a similar rate of respiration, as both are alive. The nongerminating peas will show a smaller change in gas volume compared to the germinating peas due to cellular respiration. The germinating peas will show a smaller change in gas volume compared to the nongerminating peas due to production of O2. The nongerminating peas serve as a second control and should show no volume change due to cellular respiration.

The nongerminating peas will show a smaller change in gas volume compared to the germinating peas due to cellular respiration.

Predict the result if KOH were not added to the vial. The volume of gases in the vial would remain constant as each molecule of O2 used in cellular respiration would be replaced by a molecule of CO2. The volume of gases in the chamber would increase, pushing water out of the pipette. No O2 would enter the chamber, cellular respiration would cease, and the organism would die. CO2 would accumulate and oxygen would flow rapidly in to restore equilibrium.

The volume of gases in the vial would remain constant as each molecule of O2 used in cellular respiration would be replaced by a molecule of CO2.

Predict what would happen if the respirometer were not tightly sealed. The KOH will not be able to combine with CO2 due to the loss of pressure within the vial. Water will enter the vial, and it will no longer be possible to measure changes in gas pressure. Insufficient oxygen for cellular respiration will result, so there will be no net change in volumes. Water will push in through the pipette because the pressure in the vial will increase due to the leak.

Water will enter the vial, and it will no longer be possible to measure changes in gas pressure.