Osmosis

Question 1

Osmosis

Answer 1

the diffusion of water molecules across a selectively permeable membrane.

Question 2

Turgor pressure

Answer 2

The hydrostatic pressure that develops when water enters the cells of the plants and microorganisms.

Question 3

Hydrostatic pressure (Osmotic pressure)

Answer 3

When water moves into a body by osmosis, pressure builds up inside the body.

Question 4

Water potential

Answer 4

The tendency of water to move across a selectivelly permeablme membrane. This is used to account for differences in both concentration and pressure. It is the sum of the pressure potential and the solute potential.

• Measured in bars (1 bar is approximately equal to 1 atmosphere pressure) or megapascals (1MPa = 10 bars).
• In a living cell, water potential is always zero or negative.
• Water potential can be positive or negative.
  
  • Negative water potentiatl = TENSION

Question 5

Pressure potential

Answer 5

The pressure from any externally apllied force.

• Is zero unless some force is applied, such as that applied by a cell wall.

Question 6

Solute potential

Answer 6

The osmotic potential.

• Results from the presence of solutes.
• Always negative
• A higher concentration of solutes generates a smaller (or negative) solute potential

Question 7

Solute type/ Solute concentration

Answer 7

Solute type:

smaller molecules (water, NaCl, glucose) can diffuse across the membrane/ tubing while larger molecules cannot.

Solute concentration:

The relative concentration of solutes inside and outside the bag determines the net flow of solutes across the membrane.

• The GREATER the solute concentration, the FASTER the initial flow of solutes.

Question 8

Diffusion vs. Osmosis

Answer 8

The net movement of substances from an area of higher concentratipn to an area of lower concentration.

• Results from random movement of molecules.
• Osmosis is the diffusion of water molecules across a selectively permeable memrane.

Question 9

The Rate of Diffusion

Question 10

Turgor pressure

Answer 10

As water enters the cell, the vacuole expands until it exerts a force on the cell wall.

• In a healthy cells- the wall presses back with a pressure *equal * to and opposite of turgor pressure.

Question 11

Hypertonic

Answer 11

The solution surrounding the cell is ______ (higher solute concentration) relative to the contents of the cell.

Question 12

Plasmolysis

Answer 12

The process in which the plasma membrane collapses in a hypertonic solution because the net movement of water is out of the cell, and the TURGOR decreases.

Question 13

Hypotonic

Answer 13

The solution surrounding the cell is ________ (lower solute concentration) relative to the contents of the cell.

• The NET movement of water is INTO the cell.

Question 14

Isotonic

Answer 14

The solution surrounding the cell is ______ (equal solute concentration) relative to the contents of the cell.

• There is NO NET MOVEMENT of water in or out of the cell.

Question 15

Lysis

Answer 15

When a cell “exploads”

• Animal cells do NOT have CELL WALLS and immersing an animal cell into a hypOtonic solution wil cause the cell to expand.
• Unless the cell has a mechanism for removing EXCESS WATER, the cell will continue to expand until it breaks apart.