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

Question

A researcher observes that a particular plant cell placed in a solution exhibits incipient plasmolysis.  If the solute potential of the cell is -1.2 MPa, what is the MOST likely water potential of the surrounding solution?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
	**Primary Concept**: Water Potential and Plasmolysis
	**Related Topics**: Osmosis, Turgor Pressure, Cell Wall
	**Prerequisites**: Understanding of water movement across membranes and the components of water potential.
## SOLUTION PATHWAY
**Given Information**:
	* Incipient Plasmolysis: The point at which the cell membrane just begins to pull away from the cell wall.  This occurs when turgor pressure is zero.
	* Solute potential of the cell ($\Psi_s$): -1.2 MPa
**Method & Steps**:
	1. **Water Potential at Incipient Plasmolysis**: At incipient plasmolysis, the turgor pressure ($\Psi_p$) is zero.
		Reasoning: Turgor pressure is the pressure exerted by the protoplast against the cell wall. When plasmolysis begins, the protoplast is no longer pushing against the wall.
		Formula/Rule: $\Psi = \Psi_s + \Psi_p$
	2. **Calculating Water Potential**: Since $\Psi_p = 0$, the water potential ($\Psi$) of the cell equals its solute potential ($\Psi_s$).
		Working: $\Psi = \Psi_s + 0 = \Psi_s$
		Key Point:  At equilibrium, the water potential of the cell and the surrounding solution are equal.
	3. **Water Potential of the Solution**: The water potential of the surrounding solution must be equal to the water potential of the cell at incipient plasmolysis.
		Result: $\Psi_{solution} = \Psi_{cell} = -1.2$ MPa
		Verification: The solution having the same water potential as the cell at incipient plasmolysis ensures no net movement of water, consistent with the observation.
## OPTION ANALYSIS
[A] ✓: -1.2 MPa: This is the correct answer.  At incipient plasmolysis, the water potential of the solution equals the solute potential of the cell, which is -1.2 MPa.
[B] :x: -1.0 MPa: If the surrounding solution had a higher water potential (-1.0 MPa), water would move into the cell, preventing plasmolysis.
[C] :x: -1.4 MPa: If the surrounding solution had a lower water potential (-1.4 MPa), more water would leave the cell, leading to full plasmolysis rather than incipient plasmolysis.
[D] :x: -0.8 MPa:  Similar to option B, a higher water potential in the solution would cause water to move into the cell, preventing plasmolysis.
## LEARNING AIDS
	**Common Mistakes**:
		1. Confusing solute potential and water potential: Remember that water potential is the sum of solute potential and pressure potential.  At incipient plasmolysis, pressure potential is zero.
		2. Misinterpreting incipient plasmolysis: Incipient plasmolysis is the beginning of plasmolysis, not full plasmolysis.
	**Quick Tips**:
		1. Remember that water moves from high water potential to low water potential.
		2. At incipient plasmolysis, $\Psi_{cell} = \Psi_{solution} = \Psi_s$

Mr. NARESH KUMAR K · Answer

The correct Option is "-1.2 MPa"

Mr. NARESH KUMAR K · Answer

-1.0 MPa

Mr. NARESH KUMAR K · Answer

-1.4 MPa

Mr. NARESH KUMAR K · Answer

-0.8 MPa

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