Question

What is the direction of the movement of water if two cells have the same osmotic pressure but differ in turgor pressure?

• A. No net flow
• B. From lower turgor pressure to higher turgor pressure
• C. From higher turgor pressure to lower turgor pressure
• D. Data insufficient

Answer 1

Answer: (C)

From higher turgor pressure to lower turgor pressure

'Diffusion pressure deficit' (DPD) is also known as suction pressure (SP). DPD is responsible for the movement of water in a plant. Water moves from a region or cell of low DPD to a cell or region of high DPD. The DPD is calculated as the difference of osmotic pressure (which is responsible for entry of water into a cell) and turgor pressure (which opposes entry of water into a cell).

In a fully turgid cell, osmotic pressure is equal to turgor pressure and hence DPD is zero. If two cells have the same DPD and are placed in contact, water will move from the cell having higher TP to the cell having lower TP, because the water cannot enter into the former cell due to higher opposing force. Also as turgor pressure develops on the entry of water, a higher value of TP means comparatively more water content in a cell.

So, the correct answer is option C.