AP BIOLOGY

Detailed explanation-1: -Guard cells regulate the opening and closing of stomata. The outer walls of guard cells are thin and their inner walls are thickened. This unequal thickening of guard cells causes the stomata to open and close. When water flows into the guard cells, it swells up and causes the stomata to open.

Detailed explanation-2: -Upon the incoming of water inside the guard cells, they swell up to become like a curved banana surface, due to which the stomatal pore opens up. When the guard cells lose water, they become flaccid and straight and thus, close the stomatal aperture. Guard cells and stomata regulates the respiration process in plants.

Detailed explanation-3: -Each stoma is surrounded by a pair of sausage-shaped guard cells. In bright light the guard cells take in water by osmosis and become plump and turgid . In low light the guard cells lose water and become flaccid, causing the stomata to close.

Detailed explanation-4: -A special feature of guard cells is that they can increase or decrease their volume, thereby changing their shape. This is the basis for the opening and closing of a stoma, known as stomatal movement, which controls gas exchange necessary for photosynthesis and limits water loss.

Detailed explanation-5: -Excess loss of water through the stoma, such as during a drought, triggers chemical reactions that signal water and ions to leave the guard cells. As solutes exit the guard cells, the pair “deflates, ” subsequently closing the stoma like two flat balloons.