Question

Show by a series of diagrams, the change which a plant cell will undergo when placed in

(a) Hypertonic salt solution and

(b) Hypotonic salt solution.

Answer 1

Hypertonic Solutions:

1. A solution is hypertonic to a cell if it has a higher solute (dissolved substance) concentration than the cell does.
2. As a result, it also has a lower concentration of water than the cell does.
3. Cell membranes and plant cell walls are semipermeable barriers, which means that certain molecules can diffuse through them, while other molecules can not.
4. Many solutes are too large or charged to cross the cell membrane but water can diffuse freely. In a hypertonic environment, osmosis forces water out of the cells.

Responses to Hypertonic Solutions:

1. Plant cells have large sacs of fluid called vacuoles.
2. When full, vacuoles push outward onto the plant's cell walls, keeping them stiff.
3. When plants are placed in hypertonic solutions, their vacuoles shrink and no longer provide enough pressure to keep the plant from wilting.
4. Because of their rigidity, the cell walls keep their rectangular shape but are less plump.
5. In contrast, animal cells lack a cell wall, and so they shrivel up like raisins.

Hypotonic Solutions:

1. A solution is hypotonic to a cell if it has a lower solute concentration than the cell does.
2. As a result, it also has a higher concentration of water than the cell does.
3. Osmosis draws water out of the solution and into the cells.
4. As a result, plant and animal cells both appear plumper when placed in a hypotonic solution.
5. When viewed under a microscope, the vacuoles of plant cells appear noticeably larger.