Osmosis Flashcards
Osmosis:
• The net movement of water molecules from a region of high water concentration to a region of low water concentration (down a concentration gradient) across a partially permeable membrane until equilibrium Is reached
• This is a passive process
When is a solution dilute?
A solution is dilute when there is a high water concentration
When is a solution concentrated?
A solutions is concentrated when there is a low water concentration
A bag made from a Visking tubing (partially permeable membrane) is tied to a glass tube and filled with a strong sugar solution.
This bag is placed in a weak sugar solution.
What happens?
• Water molecules diffuse across the membrane from the weaker sugar solution (high water concentration) into the strong solution (low water concentration).
• This continues until the concentration is the same on both sides of the membrane.
• The volume of liquid in the semipermeable bag increases.
• The liquid rises up the glass tube and then stops.
What does 0.0M sucrose mean?
0.0 M sucrose means there are 0.0 moles of sucrose - means no sugar
What does the visking tube represent in the osmosis experiment?
The visking tube represents the cell membrane of a cell and it is partially permeable
Hypotonic solution:
Outside the cell is less concentrated than inside the cell (more water outside - water moves into the cell)
Isotonic solution:
Concentration is equal inside and outside the cell (no net movement of water molecules but some random movement)
How does lysis take place?
When the outside of the cell is more dilute (more water) than theinside (hypotonic), too much water mayenterand the cell willswell until it bursts
How does crenation take place?
When the outside of the cell is more concentrated than the inside(hypertonic), too much water mayleaveand the cell will shrinkand shrivel
Why won’t plant cells shrivel or burst from osmosis?
ants cells have an inelastic (made of cellulose) cell wall, so won’t shrivel or burst
How does a plant cell become turgid?
• When water enters the cell by osmosis it fills the vacuole
Thispushes against the cell wall, making itturgid
How does a plant cell becomes flaccid?
Vhen water leaves a cell by osmosis, the vacuoleshrinksandthe cell becomesflaccid
How does a plant cell becomes plasmolysed?
If too much water leavesthe cell, the cytoplasmmoves away from the cellwall and the cell becomes plasmolysed
What causes osmosis?
When a cell is submerged in water, the water molecules pass through the cell membrane from an area of low solute concentration to high solute concentration.
For example, if the cell is submerged in saltwater, water molecules move out of the cell. If a cell is submerged in freshwater, water molecules move into the cell.
