Guard cells are specialized cells located on the surfaces of plant leaves, primarily surrounding the stomata. They play a crucial role in regulating gas exchange by controlling the opening and closing of these tiny pores. This process helps plants take in carbon dioxide for photosynthesis while minimizing water loss. When guard cells absorb water, they swell and curve, causing the stomata to open. Conversely, when they lose water, they become flaccid, leading to the closing of the stomata. This dynamic regulation is essential for maintaining homeostasis in plants, allowing them to adapt to varying environmental conditions.