Diffusion and osmosis

• Osmosis


  The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
• Water concentration


  The amount of water as compared to the other molecules like sugars or salts that are dissolved in that water
• Solutes are the dissolving molecules in water
• Higher solute concentration


  Lower water concentration
• Lower solute concentration


  Higher water concentration
• Osmosis in cells


  Water particles diffuse from the outside of the cell (higher water concentration) down the concentration gradient into the cell (lower water concentration)
• Diffusion


  The net movement of particles from an area of higher concentration to an area of lower concentration
• Diffusion


  1. Molecules move about randomly

  2. Molecules spread out over time

  3. Molecules become evenly distributed
• Diffusion can happen in both gases and liquids
• Partially permeable membrane


  Only some molecules can diffuse through, like water, glucose, and amino acids. Larger molecules like proteins and starch cannot fit through.
• Diffusion is a passive process that does not require energy from the cell. Meaning it doesn’t require energy from the cell
• Factors affecting rate of diffusion


  • Concentration gradient
  • Temperature
  • Surface area
• Larger concentration gradient

  The larger the concentration gradient between two places, the higher the rate of diffusion will be.
• Higher temperature

  higher temperature give the particles more energy, meaning the particles will move around faster so they’ll diffuse more quickly
• Larger surface area


  Higher rate of diffusion
• Why does a higher temperature increase the rate of diffusion?


  Higher temperature means particles have more (kinetic) energy, So they move around faster and can diffuse more quickly
• Is diffusion an active process or passive?

  Passive because it goes with the concentration gradient where it doesn’t need any energy
• where does diffusion happen in the body(through oxygen)?


  It happens in the lungs as there is a high concentration of oxygen in the alveoli and it the blood there is a low concentration of oxygen. So oxygen is gonna move from the alveoli to the blood by diffusion
• where does diffusion happen in the body(through carbon dioxide)

  There’s a high concentration of carbon dioxide in the blood and a low concentration of carbon dioxide in the alveoli so carbon dioxide will move from a high concentration in the blood to low concentration in the alveoli
• Root hair cells transport ion such as magnesium into the plant from the soil