Describe ONE mechanism by which plants maintain internal water homeostasis. - HSC - SSCE Biology - Question 29 - 2019 - Paper 1

One primary mechanism by which plants maintain internal water homeostasis is through the regulation of stomatal opening and closing.

Plants control the movement of water out of the leaf to maintain a stable internal environment. This is primarily achieved by adjusting the size of the stomata openings. When water levels inside the plant are sufficient, the stomata open, allowing for gas exchange without significant water loss. However, in response to lower internal water levels, plants produce abscisic acid, a stress hormone that signals the stomata to close, thereby reducing water loss through transpiration.

This hormonal control mechanism ensures that plants effectively balance their water levels and respond to environmental conditions, maintaining optimal internal water homeostasis.