2.5.8 Osmosis in Animal & Plant Cells

Question 1

What is crenation?

Answer 1

• When water leaves by osmosis
• Cell shrinks and shrivels
• Fatal
• Occurs when cell is in a hypertonic environment (higher solute concentration outside cell)

Question 2

What is cytolysis?

Answer 2

• When water gains too much water by osmosis
• Cell bursts
• Fatal
• When cell is in a hypotonic environment

Question 3

What effect does a cell wall have in osmosis? What if it still loses too much?

Answer 3

• If plant cell gains or loses too much water, cell wall protects it from shrivelling or bursting
• Turgidity is important for support and strength of plant
• If it gains too much water, pressure is applied to protoplast
• However if placed in a hypertonic solution
• Water potential lower outside of cell
• Water diffuses out of vacuole by osmosis
• Volume of plant cell decreases
• Protoplast shrinks and no longer puts pressure on cell wall
• Pulls away from cell wall
• Plasmolysis

Question 4

What is hypertonic?

Answer 4

Solution has a higher solute concentration (lower water potential)

So a hypertonic environment outside of a cell would cause the cell to lose water via osmosis and shrivel (crenation)

Question 5

What is hypotonic?

Answer 5

Where the solution is low in solute concentration (high water potential)

Cell can burst (cytolysis) if the environment is hypotonic, because water will move into cell by osmosis