Lab 3 - Diffusion & Osmosis

The Primary Driving Force of Diffusion

The kinetic energy of the solute and solvent molecules. This random motion is known as Brownian motion.

The relationship between molecular weight and the rate of diffusion.

The rate of diffusion is inversely proportional to molecular weight. A lower molecular weight results in a faster rate of diffusion.

A solution that has a lower solute concentration than the cell.

Hypotonic

What happens to a cell's volume when it is placed in an isotonic solution?

The cell's volume remains constant because there is no net movement of water.

The effect of a hypertonic solution on an animal cell.

Water moves out of the cell, causing it to shrivel or crenate.

The effect of temperature on the rate of diffusion.

As temperature increases, the rate of diffusion increases because the molecules have more kinetic energy.

The term for the diffusion of water across a selectively permeable membrane.

Osmosis

What does a 'steep' concentration gradient mean?

There is a large difference in concentration over a short distance, which leads to a faster rate of diffusion.

The phenomenon demonstrated by the random, zigzagging motion of fat globules in milk.

Brownian motion.

A membrane that allows some substances to pass through it, but not others.

Selectively permeable membrane.

Why does a wilted plant placed in water become firm again?

The water is hypotonic to the plant cells, and osmosis causes water to move into the cells, restoring turgor pressure.

The relationship between a solution's concentration and the movement of water.

Water moves from an area of high water concentration (low solute) to an area of low water concentration (high solute).

Why do dialysis bags filled with a sucrose solution lose weight when placed in a solution with a higher sucrose concentration?

The outside solution is hypertonic to the solution inside the bag, so water moves out of the bag by osmosis.

The term for when the cell membrane of a plant cell pulls away from the cell wall due to water loss.

Plasmolysis.