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Rates

APBIO-YLJY4I

To measure the rate of organismal respiration, a 10 mL microrespirometer was constructed. These measure relative volume as oxygen is consumed by respiring organisms. However, as oxygen gas is consumed during aerobic respiration, it is replaced by $CO_2$ gas at a ratio of one molecule of $CO_2$ for each molecule of $O_2$. In the following protocol, the $CO_2$ produced is removed by a small piece of cotton treated with potassium hydroxide ($KOH$).

$KOH$ reacts with $CO_2$ to form the solid potassium carbonate ($K_2CO_3$). A control microrespirometer was filled with 5 mL of glass beads in one setup, while 5 mL of germinating pea seeds were placed in another. Over the course of 20 minutes, changes in the volume were measured by following the distance of a red soap bubble placed on the end of a 40 uL capillary tube at time = 0.

"Cellular Respiration: Rates." AP Biology. Nancy Cunningham, n.d. Web. 13 Mar. 2016. http://www.learnerator.com/ap-biology/q/1442/animal-studies.

Which of the following is the rate of oxygen consumption (in microliters per minute) based on this data?

A

1.9

B

19

C

3.8

D

38