Osmosis.

Question 1

Osmosis definition.

Answer 1

Net movement of water from an area of high water potential to an area of low water potential across a selectively permeable membrane (transports proteins).

Question 2

Water potential information.

Answer 2

Symbol- trident thing.
Unit- kilopascals (kPa).
The tendency for water to move.
Is either zero (pure water) or a negative number (more solute dissolved in it=more negative).
Water with a greater water potential moves first.

Question 3

Cell water potential calculation.

Answer 3

Solute potential (more solute=lower water potential) + Pressure potential (always a positive number pushes H2O out of the cell).

Question 4

Hypotonic solution.

Answer 4

Less solute in solution.
Higher water potential.
Net movement of water into the area with lower water potential.

Question 5

Hypertonic solution.

Answer 5

More solute in solution.
Lower water potential.
Net movement of water into the area.

Question 6

Isotonic solution.

Answer 6

No net movement of water.
ideal conditions for an animal cell.

Question 7

Animal cell in a hypotonic solution.

Answer 7

Higher water potential outside of the cell.
Net movement of water into the cell.
Cell will burst and die- cell lysis.
Haemolysis- blood cell lysis.

Question 8

Animal cell in isotonic solution.

Answer 8

Same water potential.
No net movement of water.

Question 9

Animal cell in hypertonic solution.

Answer 9

Lower water potential outside the cell.
Net movement of water out of the cell.
Cell shrivels or it crenates.

Question 10

Plant cell in hypotonic solution.

Answer 10

• Net movement into cell (cytoplasm + vacuole).
• Cell is turgid.
• Cytoplasm pushes against cell wall.
• Cell wall is inelastic so resists expansion.
• Cell wall exerts a pressure on the cytoplasm.
• Prevents any more water entering as positive pressure potential=negative solute potential.
• Causing water potential of cell to=0.
• Ideal conditions for a plant cell.

Question 11

Plant cell in hypertonic solution.

Answer 11

• Net movement of water out of cell.
• Cell= plasmalysed (plasmolysis).
• Whole plant= wilted.
• Cytoplasm and vacuole shrink (less volume).
• Cell membrane pulls away from the cell wall.
• The gap between the cell wall and the cell membrane is isotonic to the solution that the cell is in.

Question 12

Plant cell in isotonic solution.

Answer 12

• No net movement of water.
• 50% of cells are plasmolysed.
• 50% of cells are not plasmolysed.
• As each cell has a slightly different water potential= Incipient plasmolysis.