Osmosis

What is osmosis?

The net movement of water from an area of high water potential to an area of lower water potential across a selectively permeable membrane.

Is osmosis an active or passive process?

Osmosis is a passive process requiring no energy from ATP.

How does the movement of water molecules occur during osmosis?

Water molecules move in both directions across the membrane; the overall movement is the net movement.

What happens when water potentials are equal on both sides of a membrane?

Water moves in both directions equally, so there is no net movement.

What is water potential?

The tendency of water to leave a system by osmosis.

What two factors determine water potential?

Solute concentration (solute potential) and pressure exerted on the solution (pressure potential).

What are the units for water potential?

Water potential is measured in kilopascals (kPa).

What does a more negative water potential indicate?

A lower water potential; for example, -360 kPa is higher than -410 kPa.

What is the symbol for water potential?

The letter Ψ, with subscripts for specific potentials: w for water potential, s for solute potential, and p for pressure potential.

How does solute concentration affect water potential?

The higher the concentration of solute, the lower the water potential.

What occurs when glucose or ions enter a cell?

The water potential of that cell gets more negative or lower.