Transport in cells

• What is diffusion?

  Net movement of particles
• Particles move from an area of higher concentration to an area of lower concentration
• A larger concentration gradient increases the rate of diffusion.
• How does temperature affect the rate of diffusion?

  Higher temperature, faster diffusion
• A larger surface area results in a faster rate of diffusion
• Match the substance with its movement by diffusion:

  Oxygen in lungs ↔️ Into the blood

  Carbon dioxide in lungs ↔️ From the blood

  Urea in kidney ↔️ Into blood plasma
• Why do single-celled organisms have a high surface area to volume ratio?

  To maximise diffusion rate
• The surface area of a cube is calculated by multiplying the number of sides by the area of one side
• What are four factors that increase the effectiveness of a gas exchange surface?

  Large surface area, thin membrane, efficient blood supply, ventilation
• Osmosis involves water moving from a dilute solution to a concentrated solution.
• What is active transport?

  Movement against concentration gradient using energy
• Plant root hair cells use active transport to absorb mineral ions
• Active transport is used to absorb glucose from the gut into the blood.