Topic 4-bioenergentics

• Photosynthesis


  Process that allows plants to grow and survive
• Photosynthesis


  • Takes place in the leaves
  • Takes place in chloroplasts (subcellular structures)
  • Involves a pigment called chlorophyll that can absorb light
• Photosynthesis


  1. Absorb light energy

  2. Convert carbon dioxide and water

  3. Into glucose and oxygen
• Photosynthesis is an endothermic reaction
• Source of reactants for photosynthesis

  • Carbon dioxide diffuses into leaves through stomata
  • Water is taken up from soil by roots and transported to leaves via xylem
• Uses of glucose produced by photosynthesis

  • Cellular respiration
  • Making cellulose
  • Making starch
  • Making amino acids
  • Making oils and fats
• Plants try to maintain a good store of starch to use when photosynthesis is reduced (e.g. at night or in winter)
• Plant growth rate is often dependent on the rate of photosynthesis
• Factors that affect the rate of photosynthesis are light intensity, temperature, carbon dioxide concentration, and amount of chlorophyll