Final answer:
Light increases the net exchange of oxygen while decreasing the net exchange of carbon dioxide through the process of photosynthesis, where plants convert carbon dioxide into sugars and oxygen. Adequate light ensures plants produce more oxygen, while carbon dioxide is consumed. The Calvin cycle uses carbon dioxide to create sugars and regenerates molecules for continual photosynthesis.
Step-by-step explanation:
The question is about how light affects the net exchange of carbon dioxide and oxygen during the processes of photosynthesis and cellular respiration. Light is crucial for photosynthesis, which is the process in which plants use sunlight to convert carbon dioxide and water into sugars/carbohydrates and oxygen. During this process, carbon dioxide is consumed, and oxygen is produced. Conversely, cellular respiration, which occurs in both plants and animals, consumes oxygen and produces carbon dioxide. Therefore, when there is light, photosynthesis occurs more, leading to an increase in oxygen production and a decrease in carbon dioxide due to its consumption.
When plants close their stomata to conserve water on a hot, dry day, the rate of photosynthesis is inhibited due to a decrease in available carbon dioxide. Additionally, if stomata were sealed, oxygen levels would rise inside the leaf tissue due to continuous photosynthetic activity, while carbon dioxide levels would decrease as it continues to be used in photosynthesis but cannot be replenished from the atmosphere.
In the Calvin cycle, carbon dioxide is used to produce sugars/carbohydrates, and the cycle regenerates molecules that facilitate this process. Overall, adequate light generally ensures an increase in oxygen and a decrease in carbon dioxide exchange due to photosynthesis occurring more dominantly than respiration during daylight hours.