What Happens When Stomata Are Closed

Carbon dioxide needed for photosynthesis is obtained through open plant stomata. At night, when sunlight is no longer available and photosynthesis is not occurring, stomata close. This closure prevents water from escaping through open pores.

How does closed stomata affect photosynthesis?

The excess water exits through the stomata in a process called transpiration. So, stomata do not directly participate in photosynthesis. However, the stomata control the influx of carbon dioxide, a critical component of photosynthesis, and allow the excess oxygen to exit.

When stomata close what does this prevent from happening?

Because plants must exchange gases through their stomata, closing them prevents plants from taking up carbon dioxide (CO2). Without CO2, plants cannot make carbohydrates, and plants can only obtain this critical molecule when stomata are open.