Stomata open and close due to (a) circadian rhythm (b) genetic clock (c) pressure of gases inside the leaves (d) turgor pressure of guard cells.
Option D The pressure that develops in a cell due to osmotic diffusion of water inside it, is called turgor pressure. Stomata open and close due to turgor pressure of guard cells. When turgid, they swell and bend outward. As a result, the stomatal aperture opens. When they are flaccid, the tension from the wall is released and the stomatal aperture closes.
