Photosynthesis

• Photosynthesis


  The process by which plants use sunlight, water and carbon dioxide to create oxygen and energy in the form of sugar
• Word equation for photosynthesis

  Carbon dioxide + Water → Glucose + Oxygen
• Respiration is the opposite of photosynthesis
• Leaf adaptations for photosynthesis

  • Thin leaf to provide short distance for carbon dioxide to move by diffusion
  • Large surface area to absorb a lot of light
  • Chlorophyll to trap light and give leaves a green pigment
  • Guard cells to open and close the stomata depending on conditions
• Plants take in the carbon dioxide they need for photosynthesis through the stomata on the underside of their leaves
• Limiting factors for photosynthesis

  • Light intensity
  • Carbon dioxide concentration
  • Temperature
  • Water availability
• Increasing photosynthesis


  1. Increase light intensity

  2. Increase carbon dioxide concentration

  3. Increase temperature (up to optimum)

  4. Increase water availability
• Water is absorbed by the roots and transported to the leaves for photosynthesis
• Leaf structure

  • Cuticle
  • Upper epidermis
  • Palisade mesophyll
  • Spongy mesophyll
  • Lower epidermis with stomata
• Mineral requirements for plant growth


  • Nitrates (for protein synthesis)
  • Phosphates (for DNA and cell growth)
  • Potassium compounds (for enzymes and respiration)
• Plants can only absorb soluble mineral nutrients from the soil
• The concentration of minerals in the soil is very low
• The xylem transports water and minerals from the roots to the leaves