Diffusion

• Diffusion

  The net movement of particles from an area of higher concentration to their lower concentration
• The energy for diffusion comes from the kinetic energy of molecules in random movement
• Root hair cells have long and thin root hairs, epithelial cells have cilia, and red blood cells are biconcave to increase their surface area for absorption
• Osmosis is the diffusion of water molecules from a dilute solution (high concentration of water) to a more concentrated solution (low concentration of water) across a partially permeable membrane
• Diffusion occurs randomly at all times due to Brownian motion
• Temperature and molecule movement

  The higher the temperature, the faster molecules move as they have more energy, resulting in more collisions and therefore a faster rate of movement
• Factors influencing diffusion

  • Temperature, distance, surface area to volume ratio
• Concentration gradient

  The greater the difference in concentration gradient, the faster movement across the membrane, leading to more random collisions
• As cells grow in size, cell activity slows down, causing them to require a larger surface area to volume ratio to obtain enough nutrients
• Diffusion helps living things to obtain nutrients, get rid of waste products, and carry out gaseous exchange for respiration
• Diffusion is the random movement of particles in the direction of a concentration gradient
• Diffusion occurs in various parts of the body such as the small intestine, mesophyll cells, blood capillaries, alveoli, etc.
• The smaller the distance molecules have to travel, the faster the transport will occur
• Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration
• Molecules that diffuse down concentration gradient

  • Water
  • Oxygen
  • Carbon dioxide
• Molecules moving out of cells can include digested food products like glucose, amino acids, fatty acids, glycerol, etc.
• Diffusion, osmosis, and active transport are the main ways that molecules move into and through cell membranes
• Blood capillaries and alveoli have walls which are only one cell thick to ensure the rate of diffusion across them is as fast as possible