The rate of photosynthesis

The rate of photosynthesis

1. The limiting factor depends on the conditions

   • 1. which is limiting at a particular time depends on the environment conditions:
     • -at night the light is the limiting factor
       • -in winter the temperature is the limiting factor
         • -if its warm enough and bright enough the amount of carbon dioxide is usually limiting

2. An experiment can be done to work out the ideal conditions for photosynthesis in a particular plant

   • for example you can use a canadian ponweed
     • You would measure the amount of oxygen produced in a given time to show how fast photosynthesis is happening
       • Oxygen is produced during photosynthesis
         • Count the bubbles given off, or to be more accurate collect the oxygen in a gas syringe

3. There are three important graphs for rate of photosynthesis

   • 1. Not enough light slows down the rate of photosynthesis
     • Light= energy needed for photosynthesis. As the light levels raise the rate of photosynthesis increases but only to a certain point
       • Beyond that certain point the amount of light will not make a difference because it would be the temperature or the CO2 levels which are the limiting factors
         • In a lab you can move a lamp closer to the plant to increase the rate of photosynthesis
           • If you plot the rate of photosynthesis against the ''distance from the beaker'' you would get a weird shape graph. To get a a nice smooth curve you either need to measure the light intensity at the beaker using a light meter or do some maths with the results
   • 2.Too little carbon dioxide also slows down the rate of photosynthesis
     • CO2 is one of the raw materials for photosynthesis
       • CO2 will only increase the rate of photosynthesis to a certain point then it will not longer increase photosynthesis
         • As long as the light and CO2 are available then the limiting factor for photosynthesis is temperature
           • There are different ways to control the amount of CO2
             • one is to dissolve different amounts of sodium hydrogencarbonate in the water, which gives off CO2