Question
The opening and closing of stomota is controlled by a hormone called :
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CUET PG 2026 Agri-Business Management Question Paper (25-Mar-2026) (Shift 2)
The correct answer is
Abscisic Acid
Stomata Control by Abscisic Acid
The opening and closing of stomata, small pores on plant leaves, are primarily regulated by the plant hormone Abscisic Acid (ABA).
Mechanism of Stomatal Regulation
- Abscisic Acid (ABA): ABA acts as a stress hormone. During conditions like drought or water scarcity, ABA levels rise within the plant.
- Guard Cell Action: ABA binds to receptors on the guard cells surrounding the stomata. This triggers a signaling cascade that causes the guard cells to lose turgor (become flaccid).
- Stomatal Closure: As the guard cells lose turgor, the stomatal pore closes, significantly reducing water loss through transpiration.
- Other Hormones: While Gibberellins and Auxins are involved in plant growth and development, ABA is specifically known for its role in inducing stomatal closure. Ethylene primarily relates to fruit ripening and senescence.
Therefore, Abscisic Acid is the hormone that controls the closing of stomata, especially under stress conditions.
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