Diffusion and Osmosis

Question 1

Define permeable

Answer 1

Substance can pass through

Question 2

Define impermeable

Answer 2

Substance cannot pass through

Question 3

Define selectively permeable membrane

Answer 3

Allows some substances through but not all

Question 4

Define diffusion

Answer 4

Movement of molecules from areas of high concentration to low concentration across a semi-permeable membrane. Passive process (requires no energy)

Question 5

Give an example of diffusion in nature

Answer 5

• CO2 diffusing into leaf, O2 diffusing out of a leaf

Question 6

Give an example of diffusion in everyday life

Answer 6

• Sugar in a cup of tea spreads out
• Deodorant spreads out

Question 7

Define solute

Answer 7

Dissolves in a solvent

Question 8

Give an example of a solute

Answer 8

Sugar, salt

Question 9

Define solvent

Answer 9

Liquid that dissolves other substances

Question 10

Give an example of a solvent

Answer 10

Water

Question 11

Define solution

Answer 11

Mixture of solute and solvent

Question 12

Define osmosis

Answer 12

Movement of water molecules from areas of high water concentration to low water concentration across a semi permeable membrane. Passive process - no energy required

Question 13

Define active transport

Answer 13

Movement of molecules from areas of low concentration to high concentration across a concentration gradient. Requires energy - ATP

Question 14

Whats is the effect on animal cells in solutions of same concentration (ESC) as cytoplasm ?

Answer 14

Stay the same - isotonic

Question 15

What is the effect on animal cells in solutions with less concentration (ESC) than cytoplasm?

Answer 15

Cell gains water and may burst due to no cell wall (hypotonic)

Question 16

What is an exception when it comes to animal cells in solutions with less concentration than the cytoplasm?

Answer 16

Amoeba which lives in freshwater

Question 17

What does ESC stand for?

Answer 17

External solute concentration

Question 18

What is the effect on animal cells in solutions with more concentration (ESC) than cytoplasm?

Answer 18

Cell will lose water and may shrivel up and die (hypertonic)

Question 19

What is the effect on plant cells in solutions of same concentration (ESC) as cytoplasm?

Answer 19

Stays the same

Question 20

What is the effect on plant cells in solutions with less concentration (ESC) than the cytoplasm?

Answer 20

Water moves into the cytoplasm. Plant cells swell slightly. Turgor (pressure of the cytoplasm and vacuole against the cell wall) increases. Cell wall prevents cell from bursting

Question 21

What is the effect on plant cells in solutions with more concentration (ESC) than the cytoplasm?

Answer 21

Water moves out of the cell into its surroundings. Cell loses turgor pressure and becomes flaccid/limp -> plasmolysis. Leads to wilting

Question 22

Give some examples of how osmosis is used in food preservation

Answer 22

• Fish and meat soaked in salty solution -> microorganisms will lose water and die
• Jams use high sugar concentration -> prevents microorganisms from growing

Question 23

Draw a diagram to show the difference between turgid and plasmolysed leaf cells

Answer 23

See notes

Question 24

Explain what you did to demonstrate osmosis

Answer 24

• Two visking tubings (with selectively permeable membrane) soaked in water to soften
• Tied at one end
• A: Filled with distilled water and tied
  B: Filled with sucrose solution and tied
• Both tubes were dried and the mass of each was found
• Each tube placed in beaker of distilled water and left for 30 minutes

Question 25

What were the results of your experiment to test osmosis (include diagram)?

Answer 25

* Mass of tubing A: Stayed the same * Mass of tubing B: Increased due to osmosis. Became more turgid

Question 26

Draw diagram to show what happens when the water concentration inside the cell equals the water concentration outside the cell

Answer 26

See notes

Question 27

Draw a diagram to show what happens when the water concentration outside the cell is higher than inside the cell

Answer 27

See notes

Question 28

Draw a diagram to show what happens when the water concentration inside the cell is higher than outside the cell

Answer 28

See notes