Water & Inorganic Ions in Plants (Edexcel International A Level Biology): Revision Note

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

Water

• 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

Diagram showing the importance of magnesium and nitrate ions for plants