photosynthesis

• photosynthesis is the process where plants take in light energy and use it to produce sugar
• stage one of photosynthesis is called - light reaction
• stage 1 - light reaction

  1. light energy from the sun is trapped by the chlorophyll in the chloroplasts - this energy is converted into chemical energy which is used to make ATP, the energy is also used to split water into hydrogen and oxygen
  2. oxygen diffuses from the cell and out of the leaf
  3. the hydrogen and ATP are passed on to stage two
• stage 2 is called carbon fixation
• stage 2 - carbon fixation

  1. this is a series of enzyme controlled reactions and is therefore effected by temperature
  2. hydrogen and ATP (produced by the light reaction stage) are used with carbon dioxide to produce sugar
• the sugar produced in photosynthesis can be used for many processes like;

  • The chemical energy in sugar can be used for respiration
  • The sugar can be converted (changed) into other substances, such as starch (storage carbohydrate) and cellulose (structural carbohydrate in plant cell walls)
• the rate of photosynthesis can be calculated my measuring ___in a given time

  • the number of oxygen bubbles
  • volume of oxygen produced
  • increase in dry mass
• the 3 limiting factors for photosynthesis are;

  • temperature ( as carbon fixation is controlled by enzymes which can be denatured an extreme temperatures)
  • light intensity
  • carbon dioxide concentration
• Limiting factors will slow down the rate of photosynthesis and reduce overall plant growth

  By increasing a limiting factor, the rate of photosynthesis will increase, and greater growth rates can be achieved