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AP® Biology

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Questioning Results

APBIO-NI31YX

The following leaf disk experiment performed:

Twenty 5 mm diameter disks were ‘punched’ out of spinach leaves and placed into a plastic syringe. A small volume of 0.2% sodium bicarbonate solution was drawn into the syringe, and a vacuum was created to saturate the leaf’s air spaces with the solution. After all of the disks had sunk in the syringe, they were transferred into a clear plastic cup filled with bicarbonate solution. They were then placed under a light source, and a timer was started.

At the end of each minute, the number of floating disks were recorded.

Which of the following would be a valid question that can be asked about this experimental protocol?

A

Are the disks floating due to the release of carbon dioxide bubbles as a result of their metabolic processes?

B

Are the discs floating due to the release of nitrogen gas as a result of the effects of denitrification?

C

Are the discs floating due to the intake of carbon dioxide through stomatal openings?

D

Are the discs floating due to the production of oxygen during photolysis reactions?