Question

Find out the correct equation from the following

• A. DPD = O.P x T.P
• B. DPD = O.P + T.P
• C. DPD = O.P - T.P
• D. DPD = M.P x O.P

Hint:

- For a fully flaccid cell: \(\text{T.P.} = 0 \implies \text{DPD} = \text{O.P.}\)
- For a fully turgid cell: \(\text{O.P.} = \text{T.P.} \implies \text{DPD} = 0\) (No net water absorption).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Diffusion Pressure Deficit (DPD) represents the net demand of a cell for water, also referred to as suction pressure.
It is determined by the balance between the osmotic pressure pulling water into the cell and the turgor pressure resisting water entry.

Step 2: Key Formula or Approach:
The relation between DPD, Osmotic Pressure (OP), and Turgor Pressure (TP) is given by: \[ \text{DPD} = \text{O.P.} - \text{T.P.} \]

Step 3: Detailed Explanation:
- Osmotic Pressure (O.P.): The pressure required to prevent the entry of water into a solution through a semipermeable membrane. It is directly proportional to solute concentration.
- Turgor Pressure (T.P.): The hydrostatic pressure exerted by the cell contents against the cell wall as water enters.
- When a cell is placed in water, the entry of water is driven by O.P. but opposed by T.P.
- Therefore, the net force causing water entry (DPD) is the difference between these two opposing pressures: \[ \text{DPD} = \text{O.P.} - \text{T.P.} \]

Step 4: Final Answer:
The correct equation is DPD = O.P - T.P, corresponding to option (C).