How stoma and guard cells control the rate of photosynthesis?

Stomata are small openings on the leaf surface that regulate gas exchange, allowing carbon dioxide to enter and oxygen to exit. Guard cells, which flank each stoma, control its opening and closing in response to environmental conditions, such as light intensity and humidity. When guard cells swell with water, they open the stomata, facilitating photosynthesis by increasing carbon dioxide availability. Conversely, when conditions are dry or unfavorable, guard cells close the stomata to conserve water, thereby reducing the rate of photosynthesis.