Question

The concentrations of carbon dioxide in the air at different heights above ground in a forest change over a period of 24 hours. Use your knowledge of photosynthesis to describe these changes and explain why they occur. (5)

a) Carbon dioxide concentrations increase during the day due to photosynthesis and decrease at night due to respiration.
b) Carbon dioxide concentrations are constant throughout the day and night.
c) Carbon dioxide concentrations decrease during the day due to photosynthesis and increase at night due to respiration.
d) Carbon dioxide concentrations increase during the day and night due to soil respiration.

Answer 1

CO2 concentrations decrease during the day due to photosynthesis and increase at night because of respiration.

Step-by-step explanation:

The correct answer to the student's question about the changes in the concentrations of carbon dioxide in the air at different heights above ground in a forest over a 24-hour period is c) Carbon dioxide concentrations decrease during the day due to photosynthesis and increase at night due to respiration. During the day, plants undergo photosynthesis, using sunlight to convert water and carbon dioxide into oxygen and glucose, thereby reducing the amount of carbon dioxide in the air. At night, when photosynthesis ceases due to the absence of sunlight, plants and animals continue to respire, releasing carbon dioxide back into the atmosphere and causing its concentration to increase.