Q28 / 200 · NEET 2007 · Botany

Two cells I and II are contiguous. Cell I has osmotic pressure $10 \mathrm{~atm}$. turgor pressure $7 \mathrm{~atm}$ and diffusion pressure deficit $3 \mathrm{~atm}$. Cell II has osmotic pressure $8 \mathrm{~atm}$, turgor pressure $3 \mathrm{~atm}$ and diffusion pressure deficit $5 \mathrm{~atm}$. The result will be:

  • A
    no movement of water
  • B
    equilibrium between the two
  • Correct answer
    C
    movement of water from cell I to II
  • D
    movement of water from cell II to I.

Solution

The water moves from a lower diffusion pressure deficit to a higher diffusion, pressure deficit i.e., from A to $B$. The cell-to-cell movement of water depends on the DPD, and not on the osmotic pressure and turgor pressure. Related Theory Even though the osmotic pressures are same on both sides of the semi-permeable membrane, the movement of water will take place to equate the DPD on both sides of the membrane. Osmosis takes place from lower $D P D$ (higher water potential) to higher DPD (lower water potential). Therefore, $D P D=O P-T P$

Hence, the correct answer is option: 'C'.

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