AP BIOLOGY

Detailed explanation-1: -So why do plants wilt? Usually because they are thirsty! Many nonwoody plants rely almost exclusively on water pressure, or turgor, within their cells to keep them erect. However, plants are constantly losing water through small openings in their leaves (called stomata) in a process known as transpiration.

Detailed explanation-2: -The transpiration rate is directly proportional to the absorption of water by the roots from the soil. A decrease in water absorption causes the closure of stomata and wilting, thereby reducing the rate of transpiration.

Detailed explanation-3: -When the soil of a plant runs too low of available water, the water chains in the xylem become thinner and thinner due to less water. Effectively, the plant is losing water faster than it is absorbing it. When this happens, the plant loses its turgidity and begins to wilt.

Detailed explanation-4: -Plants transpire more rapidly at higher temperatures because water evaporates more rapidly as the temperature rises. At 30°C, a leaf may transpire three times as fast as it does at 20°C.

Detailed explanation-5: -As the relative humidity of the air surrounding the plant rises the transpiration rate decreases. It is easier for water to evaporate into dryer air than into more saturated air. Increased movement of the air around a plant will result in a higher transpiration rate.