B2.2 - Osmosis

Question 1

What is osmosis?

Answer 1

Osmosis is the diffusion of water through a partially membrane from an area of low solute concentration to an area of high solute concentration.
Osmosis is the process by which water enters a plant’s root system.

Question 2

What is the concentration of water in a dilute solution?

Answer 2

High, more water less other

Question 3

What is the concentration of water in a concentrated solution?

Answer 3

Low, less water more other

Question 4

What is an isotonic solution?

Answer 4

An isotonic solution has equal water potential and solute concentrations compared with its surroundings.

Question 5

What is a hypotonic solution?

Answer 5

A hypotonic solution is one that has a higher water potential and a lower solute concentration compared with its surroundings.

Question 6

What is a hypertonic solution?

Answer 6

A hypertonic solution = lower water potential and higher solute concentration compared with its surroundings.

Question 7

What is it called when a plant cell loses too much water?

Answer 7

• Water molecules exit cell into hypertonic solution via osmosis.
• The vacuole of plant cell shrinks and cytoplasm pulls away from the cell wall. The plant cell is now said to be flaccid.
• This process of the plant cell losing its turgidity is called plasmolysis. The cell becomes plasmolysed.

Question 8

What is it called when an animal cell loses too much water?

Answer 8

• Water molecules exit cell cytoplasm into hypertonic solution via osmosis.
• Cell membrane, because of shrinking size of cell due to water molecules leaving, contracts to form spike-like shapes – the cell is now said to be crenated.

Question 9

What is it called when a plant cell gains too much water?

Answer 9

• Water enters cell via osmosis.
• Water molecules enter vacuole of plant cell, causing it to increase in size, pushing against cellulose cell wall as a result.
• The plant cell does not burst due to strength and elasticity of material cellulose which constitutes cell wall.
• The cell is now said to be turgid.

Question 10

What is it called when an animal cell gains too much water?

Answer 10

• Water molecules enter cytoplasm of animal cell via osmosis.
• Cell will swell and burst cell membrane of the animal cell, as opposed to the plant cell.
• Process of the animal cell swelling and bursting is called cell lysis.