Question

Deplasmolysis occurs in a cell when it is placed in (a) Hypotonic solution (b) Hypertonic solution (c) Isotonic solution (d) Buffer solution

Short answer

The correct answer is (a) Hypotonic solution

Step-by-step solution

Understand Deplasmolysis

Deplasmolysis is the process where a plasmolyzed cell (a cell that was earlier in a hypertonic environment and lost water) re-absorbs water when placed in a more hypotonic environment, leading to the expansion of the cell.

Compare with Different Solutions

Hypotonic solution is a solution with lower solute concentration, causing water to enter the cell by osmosis, which could lead to the occurrence of deplasmolysis. A hypertonic solution, with a higher solute concentration, would usually lead to plasmolysis as water exits the cell. An isotonic solution, where solute concentration is equal both inside and outside the cell, would not necessarily cause deplasmolysis. The buffer solution, which resists changes in pH, is less related to the process of deplasmolysis.

Choose the Correct Solution

Given the definitions and effects of the different types of solutions on a cell and considering deplasmolysis, which is the process where a cell reabsorbs water causing it to swell or expand, the correct answer would be the hypotonic solution.

Key concepts

Hypotonic Solution

In the context of cellular biology, a hypotonic solution is one with a lower concentration of solutes compared to the inside of a cell. When a cell is placed in a hypotonic solution, water moves into the cell through a process known as osmosis. This influx of water is due to the concentration gradient, where water naturally flows from an area of low solute concentration to one of high solute concentration.

The movement of water into the cell causes it to swell and possibly even burst if the water intake is excessive. This is because the cell's atmosphere becomes more diluted compared to the exterior environment. This characteristic of hypotonic solutions can lead to the process of deplasmolysis, where a cell that was previously plasmolyzed rehydrates and expands.

Hypertonic Solution

A hypertonic solution contains a higher concentration of solutes in comparison to the interior of a cell. When a cell is immersed in a hypertonic solution, water exits the cell through osmosis. This outward flow occurs because water moves from the area of lower solute concentration inside the cell to the area of higher solute concentration outside the cell.

The loss of water causes the cell to shrink, a process known as plasmolysis. This can result in dehydration of the cell, leading to potential cell damage if prolonged. Unlike hypotonic solutions, placing a cell in a hypertonic solution is not favorable for deplasmolysis, as it induces the opposite effect by drawing water out of the cell rather than into it.

Cell Osmosis

Osmosis is a fundamental biological process through which water moves across a semipermeable membrane from a region of lower solute concentration to one of higher solute concentration. In cells, this membrane is the semi-permeable cell membrane. Osmosis is crucial for maintaining cell homeostasis and regulating the flow of water in and out of cells.

The direction of water movement during osmosis is solely determined by the solute concentration on either side of the membrane. Different solutions can dictate how a cell behaves in its respective environment. In hypotonic solutions, water enters the cell, in hypertonic solutions, water exits, and in isotonic solutions, there is an equilibrium in water movement.

Plasmolysis

Plasmolysis refers to the process where a cell loses water in a hypertonic solution, resulting in the shrinking of the cell's membrane away from the cell wall. It's a phenomenon observed primarily in plant cells, where the rigid structure allows for the interior to collapse without the entire cell losing its shape.

During plasmolysis, the space between the cell wall and cell membrane increases as the cytoplasm contracts. This is an important process that demonstrates the effects external environments can have on cellular structure and function. It highlights the susceptibility of cells to osmosis and the imperative need for suitable environments for cellular processes. Plasmolysis is reversible through deplasmolysis, when cells are rehydrated in hypotonic solutions.