PHOTOSYNTHESIS

• 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 into glucose and oxygen
• Endothermic reaction


  Reaction that requires energy from the surroundings to take place
• Carbon dioxide diffuses into the leaves through the stomata
• Water is taken up from the soil by the roots and transported to the leaves via the xylem
• Uses of glucose produced by photosynthesis

  • Cellular respiration
  • Making cellulose (to strengthen cell walls)
  • Making starch (for long-term storage)
  • Making amino acids (to make proteins)
  • Making oils and fats (for energy storage)
• Plant growth rate often depends on the rate of photosynthesis
• Factors affecting the rate of photosynthesis are light intensity, temperature, carbon dioxide concentration, and amount of chlorophyll
• Factors affecting photosynthesis


  • Light intensity
  • Temperature
  • Concentration of carbon dioxide in the air
  • Amount of chlorophyll in plants
• Chlorophyll


  Pigment within chloroplasts that absorbs the light energy needed for photosynthesis
• Plants have less chlorophyll


  They won't be able to carry out as much photosynthesis
• Factors that can reduce chlorophyll in plants

  • Disease (e.g. tobacco mosaic virus)
  • Environmental stress
  • Lack of nutrients (e.g. water)
• Limiting factors for photosynthesis are normally light, carbon dioxide and temperature
• Graphing factors affecting photosynthesis

  1. Plot light intensity on x-axis

  2. Plot rate of photosynthesis on y-axis
• As light intensity increases

  Rate of photosynthesis increases
• Rate of photosynthesis plateaus when something else becomes the limiting factor (e.g. carbon dioxide or temperature)
• As carbon dioxide concentration increases

  Rate of photosynthesis increases
• As temperature increases


  Rate of photosynthesis increases initially, then decreases as enzymes denature
• Graphs can show multiple limiting factors by comparing curves at different conditions (e.g. temperature, carbon dioxide)
• How farmers can create optimal conditions for photosynthesis

  • Use greenhouses to trap heat and provide artificial light
  • Pump in carbon dioxide
  • Use fertilizers for essential minerals
  • Use pesticides to control pests
• Creating optimal conditions for photosynthesis can be costly for farmers