cell transportation

biology revision

What is diffusion? – Movement of particles from high concentration to low concentration.

What causes diffusion?

– Random movement of particles in gases and liquids.

What is a concentration gradient?

– The difference between two concentrations.

How does a steep concentration gradient affect diffusion? .

– It makes diffusion happen faster

What is a partially permeable membrane?

– A membrane that allows some molecules through but not others.

What is osmosis?

– Movement of water from high water concentration to low water concentration through a semi‑permeable membrane.

When does osmosis stop?

– When solute concentrations are equal on both sides of the membrane.

Formula for percentage change in mass

– (final mass − initial mass) ÷ initial mass × 100.

What does a negative percentage change in mass mean?

– The tissue has lost mass.

What is active transport?

– Movement of substances against a concentration gradient using energy.

What carries out active transport?

– Transport proteins in the cell membrane.

Which processes are passive and require no energy?

– Diffusion and osmosis.