Photosynthesis & Plant Growth

• Photosynthesis

  A series of chemical reactions that help plants make food by converting light energy into chemical energy
• Limiting factors for photosynthesis

  • Suitable temperature
  • Presence of chlorophyll
  • Light
• Test for starch

  1. If starch present, leaf turns blue-black after adding iodine

  2. If not, leaf turns brown
• Independent variable


  The variable you change
• Dependent variable


  The variable you measure
• Plant cell

  • Cell wall maintains cell shape
  • Cell membrane controls flow of material in and out of cell
  • Nucleus controls all activities in cell
  • Mitochondria produce energy
  • Chloroplast is site of photosynthesis
  • Vacuole stores food
• When water enters the vacuole

  1. It swells and pushes against the cell wall

  2. Cell becomes turgid and firm

  3. Provides turgor pressure to support the plant
• Without water

  Vacuole shrinks and the cell loses its shape and becomes flaccid
• Leaves

  • Entry and exit point for gases
• Stems

  • Connect roots to the leaves, flowers & fruits
  • Contain cells specially adapted for transportation of water, minerals & sugars
• Roots

  • Absorb water and minerals from the soil
• Plant transportation tissues

  • Xylem transports water and minerals up the stem from the roots to the shoots
  • Phloem transports sugars produced in the leaves up and down the stem to growing and storage tissues
• Types of fertilisers

  • Organic
  • Inorganic
• Mineral salts

  • Help plants grow
  • Nitrate - needed for growth & repair, makes protein, new cells, DNA, chlorophyll
  • Magnesium - needed for chlorophyll
  • Phosphorus - development of roots, flowers, seeds
  • Potassium - helps resist diseases, promotes root, flower, fruit development
• Photosynthesis

  CO2 + H2O = O2 + C6H12O6
• Importance of water

  For transport, cooling, support and nutrition
• Main mineral salts that help plant growth

  • Nitrate
  • Magnesium
  • Potassium
  • Phosphorus
• The vascular tissues of a plant are xylem and phloem
• What is the function of Nitrate?

  Makes protein, DNA, and chrollophyl
• How to test the presence of Oxygen?

  By using a glowing splint; splint will relight if present
• How to test the presence of Carbon Dioxide?

  By using lime water; solution will turn cloudy if present