2A 3 OSMOSIS: A SPECIAL CASE OF DIFFUSION

What is osmosis?

1. Ósmosis is the free movement of water molecules through a partially permeable membrane, down a concentration gradient.

What is a solute

1. The solute is the substance hat gets dissolved.

What is the solvent

The solvent is the solution that dissolves the substance

Explain the definition of osmosis. The net movement of free water molecules through a partially permeable membrane down a water potential gradient.

1. Free water is water molecules that can move, cuz some water i.e. in ice cannot move.

2. Partially permeable membrane is a membrane in which water can pass through, but not all substances like lipids or starches. E.g. cell surface membrane or nuclear membrane.

3. Water potential gradient, A place of high water potential to low.

What is water potential

1. Water potential of a solution measures the concentration of free water molecule not associated with solute molecules.

2. I.e. water as the solvent.

What is osmotic concentration

1. It is the concentration of the amount of the solute.

What is isotopic solution

1. The isotonic solution is when the osmotic concentration of the solutes in the solution are the same as that in the cells.

What is hypertonic solution

Hypertonic solution is when the osmotic concentration of the the solutes in solution is lower than that of the cytoplasm in the cell.

What is hypertonic solution

1. Hypertonic solution is when the osmotic concentration of the solutes in of the solution is higher than that of the cells.

Describe the effects of the different states of solutions on animal cells.

1. Isotonic, no change

2. Hypertonic, water moves out of cell and it shrivels.

3. Hypotonic, water moves into cell and it bursts.

What happens to a plant cell if in hypotonic solution

1. The plant cell has a cellulose cell wall that prevents it from bursting when in hypotonic solution.

2. It enters a state of turgor.

How does the cellulose cell wall prevent the plant cell from bursting

1. As water enters the cell, the cytoplasm swells and presses against the cel wall, generating hydrostatic pressure.

2. The inward pressure of the cell wall on the cytoplasm increases until it cancels out the tendency of the water molecules to move in.

3. this inward pressure is called the pressure potential.

What is turgor of a plant cell

1. It is when the osmotic force moving water into the plant cell is balanced by pressure potential forcing it out, the plant cell is rigid, in a state known as turgor.

What is incipient plasmolysis

1. It i when a plant cell is placed in a hypertonic solution, water moves out of the plant cell and turgor is lost.

2. The cell membrane begins to pull away from the cell wall as the protoplasm shrinks.

Do plant cells change much when in turgor or plasmosyised

1. No, the plant cell shapes do not changed much whether plasmosyed or turgor.