Edexcel International A Level Biology

Revision Notes

4.8 Water & Inorganic Ions in Plants

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Roles of Water & Ions in Plants

  • Plant cells perform a variety of different functions
  • In order to perform these functions efficiently, the plant requires water and inorganic ions (minerals)
  • They are absorbed through the root hairs on the root and travel up the stem in xylem vessels
  • A plant will show certain symptoms (e.g. yellow leaves, stunted growth) when there is a deficiency in any one of these substances


  • Important component required for photosynthesis
  • Provides a transport medium for minerals
  • Maintains turgidity in plant cells though pressure in cell vacuoles
  • Regulates temperature - to ensure that enzymes can function at their optimum rate

Magnesium ions

  • Important requirement for the production of chlorophyll
  • This provides the green colour of stems and leaves and is essential for photosynthesis

Nitrate ions

  • Without nitrate ions, the plant would be unable to synthesise DNA, proteins and chlorophyll
    • Enzymes are important proteins for which nitrate ions are needed
  • These molecules are essential for plant growth, as well as the production of fruit and seeds

Calcium ions

  • These form important cell wall components
  • Plants require calcium ions for proper growth

Mineral deficiencies in plants

Diagram showing the importance of magnesium and nitrate ions for plants

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Author: Marlene

Marlene graduated from Stellenbosch University, South Africa, in 2002 with a degree in Biodiversity and Ecology. After completing a PGCE (Postgraduate certificate in education) in 2003 she taught high school Biology for over 10 years at various schools across South Africa before returning to Stellenbosch University in 2014 to obtain an Honours degree in Biological Sciences. With over 16 years of teaching experience, of which the past 3 years were spent teaching IGCSE and A level Biology, Marlene is passionate about Biology and making it more approachable to her students.