[Campbell Biology P.847] A plant is placed in an environment with high temperature, low humi... | Practice Question

A plant is placed in an environment with high temperature, low humidity, and strong wind. Which of the following is the most likely immediate effect on the plant's transpiration rate and stomatal response?

  • A: Transpiration rate decreases; stomata remain open to cool the leaf.
  • B: Transpiration rate increases; stomata may partially close to conserve water, leading to potential wilting if water supply is insufficient.
  • C: Transpiration rate remains unchanged; guard cells become flaccid due to K+ loss.
  • D: Transpiration rate decreases; abscisic acid (ABA) levels drop, promoting opening.

Explanation

High temperature, low humidity, and strong wind all increase the water potential gradient between the leaf and the air, thus increasing the rate of transpiration. If water loss is excessive and water supply is insufficient, the plant may experience drought stress, leading to stomatal closure often mediated by ABA to conserve water, and ultimately wilting due to loss of turgor.