5.5 Osmosis

Question 1

Define osmosis

Answer 1

Diffusion of water from high water potential to low water potential through a partially permeable membrane down a water potential gradient.

Question 2

Define water potential

Answer 2

Pressure exerted by water molecules as they collide with a membrane

Question 3

What’s the highest possible water potential?

Answer 3

0 - pure water

Question 4

How does concentration of solutes affect water potential?

Answer 4

More solutes = more negative water potential

Question 5

Define hydrostatic pressure

Answer 5

Pressure created by water in an enclosed system

Question 6

What happens if animal cells are placed into solutions with higher water potential?

Answer 6

Water enters the cell (as it has lower water potential), increasing hydrostatic pressure

Question 7

Define cytolysis.

Answer 7

Bursting of animal cell due to increased hydrostatic pressure as water enters by osmosis

Question 8

What happens when an animal cell is placed into a solution with lower water potential?

Answer 8

Cytoplasm loses water to solution by osmosis down a water potential gradient

Question 9

How do plant cells control hydrostatic pressure inside them?

Answer 9

Water enters by osmosis
Hydrostatic pressure increased - there’s pressure against cell wall by plasma membrane
As turgor pressure increases, cell resists further entry of water. Cell = turgid

Question 10

Define turgor.

Answer 10

Pressure exerted by plasma membrane against cell wall in plant cell