In flowering plants, carbon dioxide (CO2) is produced during the process of respiration, particularly in the mesophyll cells, which are primarily located in the leaves. Here's how CO2 produced by these cells reaches the atmosphere:
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Cellular Respiration: Mesophyll cells, like all living cells, perform cellular respiration to convert glucose and oxygen into energy (ATP), producing carbon dioxide and water as byproducts. The overall equation for respiration is: \[ \text{C}6\text{H}{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy (ATP)} \]
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Diffusion of CO2: After CO2 is produced within the mesophyll cells, it diffuses out of the cells into the intercellular spaces within the leaf. The concentration of CO2 in these intercellular spaces becomes higher than in the external atmospheric air, creating a concentration gradient.
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Stomatal Opening: Gas exchange in leaves primarily occurs through small openings known as stomata, which are found on the surface of the leaves. Stomata consist of pairs of specialized cells called guard cells that regulate their opening and closing. When the stomata are open, CO2 can diffuse from the internal air spaces of the leaf into the external atmosphere.
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Atmospheric Release: As CO2 diffuses out through the open stomata, it enters the atmosphere, contributing to the global carbon cycle.
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Regulation of Stomata: The opening and closing of stomata are influenced by various factors, including light, humidity, temperature, and internal CO2 levels, allowing the plant to effectively manage gas exchange according to its physiological needs.
In summary, carbon dioxide produced by respiring mesophyll cells diffuses into intercellular spaces, moves through the stomata, and is released into the atmosphere, playing a role in both respiration and the broader carbon cycle.