Which outcome occurs when elevated levels of abscisic acid (ABA) reach guard cells surrounding the stomata?

💡 Explanation

When ABA reaches guard cells, it activates calcium channels triggering an efflux of ions like potassium and chloride, which subsequently decreases turgor pressure via proton pumps inducing stomatal closure. Therefore proton pump activation results, rather than bloom, increased transpiration or cell expansion which rely on converse hydrostatic and hormonal gradients.

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