2.15, 2.16. 2.17 Movement in and out of cells

What is diffusion

The net movement of particles from a region of higher concentration to lower concentration down a concentration gradient.

What does diffusion result in?

Equilibrium which is when all the particles are spread equally.

What can affect the rate of diffusion?

Surface area, temperature, concentration gradient, diffusion distance

How does a larger surface area change the rate of diffusion?

The larger the surface area, the more space there is for particles to diffuse across, increasing the rate of diffusion

How does a higher temperate affect the diffusion rate?

Higher temps give particles more energy to move faster, increasing the rate of diffusion

How does a steeper concentration gradient affect the diffusion rate?

The steeper the concentration gradient, the greater the difference, so more particles will move from the higher concentration to lower concentration to achieve equilibrium, therefore increasing the rate.

How does a greater diffusion distance affect the rate of diffusion?

The greater the distance, the longer the particles must travel to achieve equilibrium, therefore lowering the rate of diffusion.

How do substances move in and out through the cell membrane?

By diffusion

What is osmosis?

movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane

How does water move through cells?

Across the cell membrane using osmosis

Examples of diffusion in living systems

• lungs: oxygen moves into blood, CO2 moves out in alveoli

• Plants: gases enter/exit through stomata

• Body: nutrients move from blood to tissues

Examples of osmosis in living systems

Plants: roots absorb water from soil

Animals: water moving across cell membranes

Examples of diffusion in non living systems

Perfume/odour spreading in a room

Examples of osmosis in non living systems experiment

Potato experiment: potato cylinders gain or lose mass when placed in different salt/sugar solutions