Carbon dioxide concentrations: The amount of carbon dioxide in the air is influenced by several factors, including respiration of plants. Figure 1.46 on the following page shows28 the concentration of...

Carbon dioxide concentrations: The amount of carbon dioxide in the air is influenced by several factors, including respiration of plants. Figure 1.46 on the following page shows28 the concentration of carbon dioxide in parts per million (PPM) ina closed (that is, unventilated) greenhouse on a

cold, clear day during a 24-hour period beginning

at 6 a.m.

a. At what time is carbon dioxide in the greenhouse

at its lowest concentration?

b. When is carbon dioxide in the greenhouse at its

highest concentration?

c. Photosynthesis results in a carbon dioxide exchange between plants and the surrounding air.

During what times do the plants in the greenhouse show a net absorption of carbon dioxide?

d. What is happening in terms of carbon dioxide

exchange from 6 a.m. to 9 a.m.?