• 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

• The following experiment could be done with any one of the mineral ions mentioned earlier
• For this example, the focus will be on investigating the effect of a?calcium deficiency?on plants

Apparatus

• Nutrient broths
• Test tubes
• Seedlings
• Aluminium foil
• Mass balance

Method

• Prepare three nutrient broths containing every mineral that a plant requires, but with different concentrations of?calcium ions?in each (high,?medium?and?low)
  • Label three test tubes for each of the nutrient broths (three 'high', three 'medium' and three 'low' = nine in total)
• Take?nine seedlings, ensuring that they are from the same plant and are the same age, and?record the mass?of each
• Place one seedling on top of each test tube,?suspending the roots?in the nutrient broth
• Cover the test tubes with aluminium foil to?keep light away?from the broth
• Place the test tubes near a?source of light?and leave them for a few days
• Remove each plant from the broth and carefully blot it dry before?measuring the mass?again
• Record the end mass and use that to?calculate the mean change in mass?of the plants for each of the different nutrient broths
• Make a note of any?physical differences?between the plants of the different groups

Variation of the practical

• Another variation of the experiment mentioned above, is to investigate the effect on plant growth when the mineral is?completely lacking
• In this experiment you would have broths that contains all of the minerals, except the one that is being investigated
• There would also need to be two?control broths
  • One would contain all the minerals
  • The other would contain no minerals