Cellular Transport - Active Transport (OCR Gateway GCSE Biology: Combined Science)

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Active Transport

  • Diffusion and osmosis rely upon the passive (no energy is required) transport of substances down concentration gradients
  • Cells also need to be able to transport substances across the cell membrane against a concentration gradient.
    • This requires the input of energy (in the form of ATP) released from cellular respiration
  • Active transport moves substances from a more dilute solution to a more concentrated solution

Active transport across the cell membrane, IGCSE & GCSE Biology revision notes

Active transport across the cell membrane involves protein carrier molecules embedded in the cell membrane


  • Root hair cells lining the surface of plant roots need to move minerals such as magnesium ions from a region of lower concentration (the very dilute solution of minerals in the soil surrounding the roots) to a region of higher concentration (inside the cytoplasm of the cell)
  • Mineral ions are needed by plants to function healthily
    • Magnesium ions are needed to make chlorophyll
    • Nitrate ions are needed to make amino acids and therefore for protein synthesis (and subsequently growth)


  • Nutrients (e.g. glucose) can diffuse into the bloodstream from the small intestine (the gut)
  • But this is dependent on a concentration gradient existing between the small intestine and the bloodstream
    • i.e. a higher concentration of glucose in the small intestine compared to the bloodstream
  • Active transport allows nutrients like glucose to be transported into the bloodstream from the small intestine even when the concentration gradient is in the wrong direction
    • i.e. when the concentration of sugar molecules in the bloodstream is higher
    • This is essential to stop us from starving as glucose can continuously be transported to the bloodstream

Exam Tip

Remember - an important difference between active transport and diffusion is that active transport requires energy whereas diffusion is a passive process

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Author: Phil

Phil has a BSc in Biochemistry from the University of Birmingham, followed by an MBA from Manchester Business School. He has 15 years of teaching and tutoring experience, teaching Biology in schools before becoming director of a growing tuition agency. He has also examined Biology for one of the leading UK exam boards. Phil has a particular passion for empowering students to overcome their fear of numbers in a scientific context.