Question

Refer the given figure which shows a section of plant roots having a root hair. Which of the following statements is correct for absorption of water to occur?

• A. The water potential of the soil water is zero.
• B. The water potential of cell Z is the lowest.
• C. The water potential of cell Y is higher than cell X.
• D. The water potential of cell Y is lower than cell Z.

Answer 1

Answer: (B)

The water potential of cell Z is the lowest.

Water moves into the root hair cells because it is moving down a water potential gradient since a root cell has relatively low water potential due to its inorganic ions and organic substances. Water will enter through the membrane and into the cytoplasm and vacuole. From the root hair cells, water again moves down a concentration gradient toward the xylem. Hence, the water potential of the soil is highest followed by the cell X, Y and cell Z, Z having the lowest water potential.