Movement of Molecules: Passive Transport, Simple Diffusion, Facilitated Diffusion (For CBSE, ICSE, IAS, NET, NRA 2022)

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Passive Transport

  • In Passive Transport, the transportation of molecules across the membrane is using a concentration gradient.
  • Cellular energy is not required.
  • The movement of biochemical is from higher to the lower concentration.
  • Natural entropy is used for movement form higher to the lower concentration.
  • At equilibrium there is no net transport of molecules.
  • Using this process all the waste molecules using water and carbon dioxide get separated.
  • This process occurs in the kidneys and the liver including the alveoli of the lungs during the exchange oxygen and carbon dioxide.
  • Some of the examples of passive transport are Osmosis, diffusion and facilitated diffusion.
Passive Transport

Types of Passive Transport

Simple Diffusion

  • There is a net movement of atoms, ions, and molecules.
  • Movement is from a region of higher concentration to a region of lower concentration.
  • Driven by a gradient in concentration.
  • Simple diffusion is used by many non-polar molecules.
Simple Diffusion
Simple Diffusion

Facilitated Diffusion

  • Also known as facilitated transport or passive-mediated transport.
  • Involves process of spontaneous passive transport.
  • doesn՚t directly require chemical energy from ATP hydrolysis.
  • The transportation is based on molecular binding.
Facilitated Diffusion
Facilitated Diffusion


  • Transportation of water and other molecules or substance.
  • The transportation takes place through the selectively permeable cell membrane.
  • Factors affecting this transportation:
    • Cell having less negative water potential.
    • Soluble potential of a molecule.
    • Pressure potential of a cell membrane.
Transportation of Water and Other Molecules

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