Simulation · Biology · Class 11
How a stoma opens
From the lesson Epidermis and stomata in Anatomy of Flowering Plants. Change the values and watch what happens.
How a stoma opensBiology · Class 11
The idea behind it
NCERT §6.1.1, Figure 6.1
- In the primary body of a plant, the epidermis is the layer on the very outside. Its cells are elongated and packed tightly into one unbroken layer, which is usually a single cell thick.
- Epidermal cells are parenchyma: a large vacuole with only a thin film of cytoplasm pressed against the wall.
- A waxy, thick cuticle often covers the outer surface and cuts down water loss. Roots have no cuticle.
- Stomata are found in the epidermis of leaves and control transpiration and the exchange of gases.
- Each stoma has two guard cells around a pore. Guard cells are bean-shaped in most plants but dumb-bell shaped in grasses.
- The wall of a guard cell facing the pore (inner wall) is heavily thickened; the wall away from the pore (outer wall) is thin. Guard cells contain chloroplasts and control opening and closing.
- Epidermal cells next to the guard cells may change shape and size; these are subsidiary cells.
- Stomatal apparatus = stomatal pore + guard cells + the subsidiary cells around them.