Water Potential

Question 1

What is osmosis?

Answer 1

It’s the diffusion of water molecules across a partially permeable membrane down a water potential gradient.

Question 2

For ANIMAL cells, what happens when the surrounding solution has a higher water potential than the cell (hypotonic solution)?

Answer 2

The net movement of water molecules is into the cell so the cell bursts.

Question 3

For ANIMAL cells, what happens when the surrounding solution has the same water potential as the cell (isotonic solution)?

Answer 3

The water molecules pass into and out of the cell in equal amounts so the cell stays the same.

Question 4

For ANIMAL cells, what happens when the surrounding solution has a lower water potential than the cell (hypertonic solution)?

Answer 4

The net movement of water molecules is out of the cell so the cell shrinks.

Question 5

For PLANT cells, what happens when the surrounding solution has a higher water potential than the cell (hypotonic solution)?

Answer 5

The net movement of water is into the cell so the vacuole swells. The vacuole and cytoplasm push against the cell wall. The cell becomes turgid.

Question 6

For PLANT cells, what happens when the surrounding solution has the same water potential as the cell (isotonic solution)?

Answer 6

The water molecules move into and out of the cell in equal amounts so the cell stays the same.

Question 7

For PLANT cells, what happens when the surrounding solution has a lower water potential than the cell (hypertonic solution)?

Answer 7

The net movement of water is out of the cell so the cell becomes flaccid. The cytoplasm and the membrane pull away from the cell wall. This is called plasmolysis.