1.3-transport in cells

• What is diffusion?

  The net movement of particles from high to low concentration
• What happens during diffusion in the lungs?

  Oxygen diffuses into blood, CO2 into lungs
• What are the three main factors affecting diffusion rate?

  • Concentration gradient
  • Temperature
  • Surface area
• How does a larger concentration gradient affect diffusion?

  A larger gradient increases the rate of diffusion
• What effect does temperature have on diffusion?

  Higher temperature increases the rate of diffusion
• How does surface area influence diffusion?

  Larger surface area increases the rate of diffusion
• How are single-celled organisms adapted for diffusion?

  They have a large surface area to volume ratio
• How is surface area to volume ratio calculated?

  • Surface Area = Number of Sides x (Side Length x Side Width)
  • Volume = Length x Width x Depth
  • Ratio = Surface Area:Volume
• What is osmosis?

  The movement of water from dilute to concentrated solution
• What factors increase the effectiveness of a gas exchange surface?

  • Large surface area
  • Thin membrane
  • Efficient blood supply
  • Ventilation
• What does it mean when a solution is isotonic to a cell?

  External and internal solution concentrations are the same
• What does it mean when a solution is hypertonic to a cell?

  External solution concentration is higher than internal
• What happens to an animal cell in a very hypotonic solution?

  Water moves in, causing the cell to burst
• What does it mean when a solution is hypotonic to a cell?

  External solution concentration is lower than internal
• What happens to an animal cell in a very hypertonic solution?

  Water moves out, causing the cell to shrivel
• How do plant leaves and stems remain rigid?

  Turgor pressure from water moving in by osmosis
• What is active transport?

  Movement of molecules against a concentration gradient
• What happens to a plant cell in a very hypertonic solution?

  Water moves out, causing plasmolysis
• How do plant root hair cells use active transport?

  They take up mineral ions from dilute soil solutions
• How is active transport used to absorb digestion products?

  Glucose is transported from gut to blood
• What are the products of digestion absorbed by active transport?

  • Glucose
  • Mineral ions (e.g., magnesium, nitrates)