3.2 Osmosis Flashcards
What is osmosis?
Osmosis is the net movement of water molecules from an area of higher water potential (dilute solution) to an area of lower water potential (concentrated solution) through a partially permeable membrane.
What does a partially permeable membrane do in osmosis?
A partially permeable membrane allows small molecules (like water) to pass through but blocks larger molecules (like sugars or proteins).
What happens to a cell when it is immersed in a solution with a higher concentration of solute?
The cell will shrink and become flaccid (water moves out of the cell via osmosis). In plant cells, it can also lead to plasmolysis where the cell membrane pulls away from the cell wall.
What happens when a cell is immersed in a solution with a lower concentration of solute?
The cell will swell and become turgid (water moves into the cell via osmosis), increasing turgor pressure against the cell wall.
What is turgor pressure?
Turgor pressure is the pressure that the cell membrane exerts on the cell wall when the cell is turgid, caused by water moving into the cell during osmosis.
What is plasmolysis?
Plasmolysis occurs when a plant cell loses too much water, causing the cell membrane to pull away from the cell wall.
What happens to a plant cell in an isotonic solution (same solute concentration inside and outside)?
The cell stays the same, with no net movement of water. The cell is neither turgid nor flaccid.
How is osmosis important for plants?
Osmosis helps plants take up water from the soil through root hair cells. This water is essential for photosynthesis and support (turgor pressure).
How does osmosis occur in animals?
In animals, osmosis helps regulate the balance of water in cells, preventing them from shrinking or bursting.
How can osmosis be investigated in the lab?
You can use dialysis tubing, a partially permeable membrane, to demonstrate osmosis. Fill it with concentrated sucrose solution, then place it in water. Water moves from the beaker into the tubing, showing osmosis.
What are the effects of osmosis on plant tissues in solutions of different concentrations?
In a hypotonic solution (low solute concentration), plant cells become turgid.
In an isotonic solution (same solute concentration), plant cells stay the same.
In a hypertonic solution (high solute concentration), plant cells become flaccid and may undergo plasmolysis.
What is the role of water potential in osmosis?
Water potential is the tendency of water to move. It helps explain how water moves from areas of higher water potential (less concentrated solutions) to areas of lower water potential (more concentrated solutions) during osmosis.
