Final answer:
The lack of water causes plants to close their stomata to conserve moisture, which limits the absorption of CO2 and reduces the efficiency of the Calvin cycle in photosynthesis, potentially affecting plant growth and organisms dependent on plants.
Step-by-step explanation:
The lack of water in an environment can significantly impact the amount of carbon dioxide absorbed by a plant. During photosynthesis, plants open stomata to allow CO2 to enter, which is used in the Calvin cycle to synthesize sugars. However, in dry conditions, the stomata may remain closed to conserve water, leading to a decrease in CO2 uptake and thus reducing the efficiency of photosynthesis. Additionally, hot temperatures and bright sunlight can exacerbate this effect, further slowing down the C3 pathway of carbon fixation due to the closure of stomata.
With the stomata closed, there's an insufficient supply of CO2 within the leaf, which may cause the Calvin cycle to slow down or even stop. This limitation not only affects the plant's growth by reducing sugar production but can also impact organisms that rely on these plants for survival. It's important to note that while lack of water can reduce growth, excessive water can also harm plants due to complications like anaerobic conditions in waterlogged soils.
The atmosphere acts as a major reservoir of carbon in the form of carbon dioxide, and the interplay between atmospheric CO2 and carbon dissolved in ocean water reservoirs is a dynamic process that influences global carbon levels.