Answer: Are turgid (full of water).
- A Lose water and become flaccid under osmotic stress
- B Are turgid (full of water)
- C Receive consistently reduced light intensity
- D Receive an ABA stress signal during drought
Correct answer: B. Are turgid (full of water)
Explanation: Guard cells become turgid (fill with water) when K+ enters them. Turgor pressure causes stomata to open.
Water can travel through cell walls (apoplast) or cell-to-cell through the cytoplasm (symplast) - but the Casparian strip at the endodermis blocks the apoplast route entirely, forcing everything through a selectively permeable membrane (symplast) before it can enter the xylem.
Concept context
Water and mineral absorption, the ascent of sap, transpiration, and phloem transport via the pressure flow hypothesis.