B1.7/B1.8 - Osmosis in animals/plants

Question 1

Osmosis

Answer 1

• special type of diffusion
• only water molecules move across a semi-permeable membrane
• move from high water potential to a low water potential
• they move down a concentration gradient

Question 2

Dilute solution

Answer 2

• High concentration of water molecules

- a low concentration of solute

Question 3

Concentrated solution

Answer 3

• low concentration of water molecules

- high concentration of solute

Question 4

Saturated solution

Answer 4

-has the maximum amount of solute dissolved in solvent

Question 5

Partially permeable membrane

Answer 5

Allows only certain substances to pass through

Question 6

Visking tubes

Answer 6

• resembles a partially permeable membrane

- used in experiments to observe osmosis

Question 7

Isotonic solutions

Answer 7

• concentration of solute in the solutions outside of the cell is the same as inside of the cell
• water does not m be in this situation

Question 8

Hypertonic solution

Answer 8

• concentration of solute in solution outside of the cell is more than the internal concentration
• higher water potential inside cell than outside
• water moves out

Question 9

Hypotonic solution

Answer 9

• concentration of solute in solution outside of cell is less than internal concentration
• higher water potential outside of cell than inside
• water move into cell

Question 10

How could the cell be damaged in a hypotonic solution

Answer 10

• as the water moves into the cell by osmosis
• lysis can occur
• the cell may swell/burst

Question 11

How can the cell get damaged in a hypertonic solution

Answer 11

• water leaves the cell through osmosis

- the cell may shrivel and die

Question 12

Example of how plants use osmosis

Answer 12

• water moves into cell
• causing vacuole to swell
• pushing cytoplasm up against the cell wall
• making it rigid

Question 13

Turgor

Answer 13

• the pressure that builds up until no more water can physically enter the anymore
• leaving the cells rigid > keeps stem/leaves firm
• this pressure is maintained by osmosis

Question 14

Osmosis in plant cells

Answer 14

• fluid around the cell must always be hypotonic to the cytoplasm = water is always moving in
• to keep water moving in the right direction and the cells turgid

Question 15

What happens when the surrounding solution of a plant cell is hypertonic

Answer 15

• water leaves cell
• cell will become flaccid due to the lack of pressure
• plant will wilt

Question 16

Plasmolysis

Answer 16

• as the cell shrivels
• the vacuole/cytoplasm shrink = decreasing in size with the cell membrane
• cell membrane will pull away from the cell wall

Question 17

What happens to plasmolysed cells

Answer 17

• they die very quickly

- unless the osmotic balance is restored