AP BIOLOGY

Detailed explanation-1: -Therefore, plants must maintain a balance between gas exchange and water loss. Water stress, high temperatures, and high carbon dioxide concentration causes stomata to close.

Detailed explanation-2: -Plants close stomata in response to their environment; for example, most plants close their stomata at night. Under drought, plants may also close their stomata to limit the amount of water that evaporates from their leaves.

Detailed explanation-3: -Stomatal opening is induced by low CO2 concentrations, high light intensity and high humidity. By contrast closing is promoted by high CO2 concentrations, darkness, drought and the plant hormone ABA.

Detailed explanation-4: -The opening and closing of stomata are controlled by specialized cells called guard cells. The turgor pressure in the guard cells controls the opening and closing of the guard cells. Stomatal pores open when guard cells enlarge as a result of water absorption and close when guard cells shrink.

Detailed explanation-5: -Stomata also limit the entry of pathogens into leaves, restricting their invasion. Drought is accompanied by the production and/or mobilization of the phytohormone, abscisic acid (ABA), which is well-known for its ability to induce stomatal closure.