SB1i- Transporting substances

• What is diffusion?

  Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration through a partially permeable membrane.
• What is osmosis?

  Osmosis is the net movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of lower water concentration.
• What is active transport?

  The movement of molecules across a cell membrane, from a region of low concentration to a region of high concentration, requiring a lot of energy from cellular respiration.
• What does partially permeable mean?

  The membrane lets some molecules in but not others
• Does the substance move up or down the concentration gradient in diffusion and osmosis?

  DOWN the concentration gradient, and FOLLOWS the concentration gradient
• Does the substance move up or down the concentration gradient in active transport?

  UP the concentration gradient, and is AGAINST the concentration gradient
• What are the 3 factors that affect the rate of diffusion?

  1. Concentration gradient

  2. Temperature

  3. Surface area
• How does concentration gradient affect diffusion?

  Concentration gradient= Difference in concentration between 2 places

  The larger the concentration gradient, the higher the rate of diffusion will be
• How does temperature affect diffusion?

  • High temperature gives particles more energy
  • Therefore, they move around faster
  • This makes them diffuse quicker
  • High temperature=Higher rate of diffusion
• How does surface area affect diffusion?

  Larger surface area=Higher rate of diffusion

  -The larger the surface area, the larger area which molecules can diffuse from
• What is water concentration?

  the amount of water as compared to other molecules like sugars or salts that are dissolved in water
• TIP

  Water moves DOWN the concentration gradient (high to low), not AGAINST it (low to high)
• Is diffusion and osmosis an ACTIVE or PASSIVE process?

  Passive as it requires no energy from the cell
• Is active transport an ACTIVE or PASSIVE process?

  Active as it requires energy from the cell
• How do molecules get transferred from one side to another in Active Transport?

  Active transport has special proteins that sit in the membrane and transfer the molecule from one side to another
• Where does the energy from Active Transport come from?

  It comes from cellular respiration, and active transport is responsible for all the energy the cell uses.
• How do root hair cells use active transport?

  -Root hair cells are adapted by having long hair like protrusions, giving them a large surface area

  -They are also adapted by having a lot of mitochondria, providing them with the energy needed for Active Transport

  -Root hair cells have a higher concentration of minerals inside the cell than outside in the soil, so they use active transport to get the other minerals.