PHOTOSYNTHESIS

• • Plants use light for their source of energy
  • The reaction plants use to trap this light energy is called photosynthesis
  • As photosynthesis takes in energy, it is an example of a endothermic reaction
• • Photosynthesis takes place in the leaves of the plants
  • Leaves contain the green chemical Chlorophyll which can absorb light energy
• Photosynthesis equation

  Carbon dioxide + water = glucose + oxygen
• $CO^2+$$H^2O-->C^6H^12O^6+$$O^2$

  (Photosynthesis)
• • When the light intensity is zero, the rate of photosynthesis is zero, plants need light to carry out photosynthesis
  • As we increase the light intensity, the rate of photosynthesis increases
  • The plant now has more light energy to carry out the photosynthesis reaction, so the reaction gets faster
• • If we increase the light intensity and the rate of photosynthesis also increases, that tells us the light intensity was limiting
  • Meaning that photosynthesis was not as fast as it could have been, because there was not enough light
  • At this point, light intensity is a limiting factor
• • If we keep increasing the light intensity, there comes a point where the rate of photosynthesis no longer increases
  • At this point light intensity is no longer the limiting factor
  • Something else is now in short supply, eg carbon dioxide in the air
• • Temperature can also affect the rate of photosynthesis - as we increase the temperature, the enzymes involved in photosynthesis work faster so the rate increases
  • However if we keep increasing the temperature, the enzymes will denature and the rate of photosynthesis falls