The pressure flow hypothesis explains how organic solutes (like sugars) are transported through the phloem in plants. It involves the movement from a source (where sugars are produced or loaded) to a sink (where sugars are used or stored). Let's analyze each statement based on the figure and the hypothesis.

Step 1: Understand the Figure
The figure shows a phloem sieve tube with regions labeled P and Q. Region P is the source (e.g., leaf), and region Q is the sink (e.g., root or fruit). Arrows indicate the flow of solutes and water.

Step 2: Evaluate Each Statement

Statement A: "A continuous high osmotic concentration is maintained in region P, which loads a sieve tube element by passively transporting solute molecules into it."
In region P (source), sugars are actively transported into the sieve tube, not passively. This active loading creates a high osmotic concentration, drawing water in. So, this statement is incorrect because loading is typically active, not passive.

Statement B: "Translocation of organic solutes takes place from region P with high turgor pressure to region Q with low turgor pressure."
This is correct. High solute concentration in P increases turgor pressure, causing flow toward Q, where pressure is lower due to unloading.

Statement C: "R shows the movement of H₂O into sieve tube elements from nearby xylem vessels by osmosis."
This is correct. Water enters the phloem from xylem due to osmosis, driven by the high solute concentration in the sieve tube.

Statement D: "In region Q, material is either consumed or is converted into insoluble storage forms resulting in decreased osmotic pressure."
This is correct. Unloading sugars in Q reduces solute concentration, decreasing osmotic pressure and allowing water to exit back to xylem.

Final Answer: The incorrect statement is A, as loading in region P is active, not passive.

Related Topics and Formulae

Pressure Flow Hypothesis: Describes phloem transport where solutes move due to a pressure gradient between source and sink.
Key Points:
- At source: Sugars are loaded (often actively) into sieve tubes, increasing osmotic pressure, drawing water from xylem.
- High turgor pressure develops, pushing sap toward sink.
- At sink: Sugars are unloaded, osmotic pressure decreases, water exits to xylem.
- Flow is driven by this pressure difference.

Formula: Water potential ($\psi$) influences movement: $\psi ={\psi }_s+{\psi }_p$, where ${\psi }_s$ is solute potential and ${\psi }_p$ is pressure potential. In phloem, high ${\psi }_p$ at source causes flow.