Diffusion

• Diffusion is the spreading out of particles in a liquid or gas from a high concentration to a low concentration down the concentration gradient until equilibruim is reached
• list 3 factors that speeds up diffusion

  • Increasing temperature
  • Increasing concentration
  • change in size/surface area
• Surface area is the total surface in contact with the surroundings
• Volume = The total content of the object
• What is exchanged in the Alveoli in the lungs?

  Oxygen ( moves from the alveoli into red blood cells) and carbon dioxide ( moves from the blood into the alveoli )
• How is Alveoli in the the lungs adapted?

  1. Large surface area
  2. Thin walls
  3. good blood supply
  4. moist lining
• What is exchanged in the villi in small intestines?

  Sugars, amino acids, fatty acids, glycerol, vitamins, minerals ( These digested foods move from the intestines into the blood)
• How is villi in small intestines adapted?

  1. Large surface area
  2. thin walls
  3. good blood supply
• What is exchanged in Gills in fish?

  Oxygen ( moves from water into the blood ) and carbon dioxide ( moves from the blood into the water )
• How is Gills in fish adapted?

  1. Gill filaments give a large surface area
  2. Lamellae increases surface area
  3. Good blood supply
• What is exchanged in the leaves in plants?

  Oxygen and water ( moves from the leaf into the air ) and carbon dioxide ( moves from the air into the leaf )
• Why is surface area : volume ratio important?

  The bigger the surface area to volume, the faster diffusion occurs

  This is because there is more space for particles to move into the object , compared to the volume of the object
• Large surface area to maximise diffusion
• Thin walls for a short diffusion pathway
• Good blood supply to maintain concentration gradient
• Well ventilated to maintain the concentration gradient
• many mitochondria to release energy for active transport
• Osmosis is the movement of water from a high water concentration to a low water concentration down the concentration gradient through a partially permeable membrane
• Active transport is the Movement of substances from a low concentration to a high concentration against the concentration gradient through a membrane with carrier proteins (it requires energy from respiration)
• Active transport : intestines

  Glucose can move from a low concentration in the small intestines to a high concentration in the blood

  (this makes sure every bit of glucose is absorbed. Glucose is used for respiration)
• Active transport: plant roots

  Mineral ions move from a low concentration in the soil to a high concentration in the root hair cell (plants require ions for healthy growth)
• Does osmosis require a membrane?

  yes (partially permeable membrane)
• Does active transport require a membrane?

  yes (carrier proteins)
• does diffusion requires a membrane?

  no
• does osmosis require energy?

  no
• Active transport requires energy
• Diffusion does not require energy