The Question is from neet-botany , and it was created by the author Mr. NARESH KUMAR K

Question

If the water potential of root cells is -0.5 MPa and the water potential of the xylem sap is -0.7 MPa, which statement BEST describes the movement of water?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
 **Primary Concept**: Water potential and water movement
 **Related Topics**: Osmosis, plant transport, xylem function
 **Prerequisites**: Understanding of water potential, its components (pressure potential and solute potential), and the direction of water movement across a semipermeable membrane.
## SOLUTION PATHWAY
**Given Information**:
  Water potential of root cells ($Ψ_{root}$) = -0.5 MPa
  Water potential of xylem sap ($Ψ_{xylem}$) = -0.7 MPa
  Water moves from a region of higher water potential to a region of lower water potential.
**Method & Steps**:
 1. Compare the water potentials of the root cells and the xylem sap.
  Reasoning: Water potential is a measure of the free energy of water. Water moves from areas of higher water potential (less negative) to areas of lower water potential (more negative).
  Formula/Rule: Water movement follows the gradient:  $Ψ_{high} ightarrow Ψ_{low}$
 2. Determine the direction of water movement based on the comparison.
  Working: Since $Ψ_{root}$ (-0.5 MPa) > $Ψ_{xylem}$ (-0.7 MPa), water will move from the root cells into the xylem.
  Key Point:  The negative sign indicates a lower free energy state (less water available). A more negative value means a lower water potential.
 3. Select the statement that accurately describes the water movement.
  Result: Water will move from the root cells into the xylem.
  Verification: The answer aligns with the principle of water movement from high to low water potential.
 ## OPTION ANALYSIS
A :x: Incorrect.  Water moves from higher to lower water potential, not vice versa.
B ✓: Correct.  The water potential gradient dictates the movement of water from root cells to the xylem.
C :x: Incorrect. There is a water potential gradient; therefore, there will be net water movement.
D :x: Incorrect. The net movement is unidirectional, from the region of higher water potential to the region of lower water potential.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Misinterpreting the negative sign in water potential:  A more negative value indicates a lower water potential.
  How to avoid: Remember that water potential is a relative measure; a more negative value means less free water and therefore water will move away from that area.
  2.Ignoring the direction of water movement: Water always moves from a higher to a lower water potential.
  How to avoid: Always compare the water potentials of the two regions to determine the direction of net water flow.
 **Quick Tips**:
  1.Think of water potential like altitude: Water 'flows downhill' from higher to lower water potential.
  2.Remember the mnemonic:  'High to low, water will go'.

Mr. NARESH KUMAR K · Answer

Water will move from the xylem into the root cells

Mr. NARESH KUMAR K · Answer

The correct Option is "Water will move from the root cells into the xylem"

Mr. NARESH KUMAR K · Answer

There will be no net movement of water

Mr. NARESH KUMAR K · Answer

Water will move equally in both directions

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