Question

What would be the ${ Ψ }_{ p }$ of a flaccid cell?
(A) Positive
(B) Negative
(C) Zero
(D) Cannot be determined

Answer 1

When a cell is placed in hypertonic solution water is transported out of the cell and therefore the cell shrinks or plasmolyzed. On the other hand when the cell is placed in a hypotonic solution the water flows into the cell causing the cells to swell and eventually resulting in their lysis. However, when the cells are placed in isotonic solutions there will be a continuous flow of water in and out of the cell and therefore the cell is claimed to be in flaccid condition.

Complete solution:
The pressure potential (${ Ψ }_{ p }$) refers to the positive pressure developed during a cell because of the entry of water through osmosis. During a turgid cell, the pressure potential is typically positive because water enters into the protoplast that generates turgor pressure. The pressure potential of a flaccid cell is sometimes zero because the water potential and pressure potential within a flaccid cell are equal. This tells us that the pressure potential of a flaccid cell would be zero.
The behavior of cells in concern to water movement depends on the surrounding solution. If the solution which is present externally is found to be more dilute than the cytoplasm, it is said to be hypotonic and the cell tends to swell in hypotonic solutions. Distilled water when it is compared to a cell is hypotonic.
When cells are placed in distilled water,it was found that water moves from outside of the cell to the inside. A cell may contain many of the solutes so it is considered hypertonic when compared to distilled water which is hypotonic. When a cell is placed in distilled water, water moves from the outside of the cell to the inside leading to swelling of the cell.

So, the correct answer is ‘Zero’.

Note:
Water, when boiled to vapor and then condensed back into liquid form in a separate container, is called ‘distilled water.’ The impurities present in the original water which does not get boiled below or near the boiling point of water are separated in the original container. Thus, distilled water is free from impurities and solutes and is a type of purified water.