AQA Biology A2 - photosynthesis

Photosynthesis

Photosynthesis is the mechanism that plants use to convert solar energy to chemical energy, the equation for this is: 6H2O + 6CO2 --> C6H12O6 + 6O2.

Photosynthesis can be limited by three main factors;

• CO2 Concentration, if there is a low concentration of carbon dioxide then it can not be used in the light independent stage of photosynthesis to bond with RuBP this causes this stage of photosynthesis to stop and no organic materials can therefore be created.
• Light intensity, light is needed for photolysis to occur in the light dependent stage of photosynthesis, if there is a low light intensity then there may not be enough energy provided to the chlorophyll molecule to excite it's electrons to a higher energy level and begin the reaction, this will also mean that the photolysis of water cannot occur which is important if the reaction is to continue.
• Temperature, if the temperature is too low or too high then the enzymes that are used in the reaction will either not have enough energy or become denatured and the enzyme-substrate complexes will not be able to be formed so no products will be needed and the reaction cannot continue.

Light Dependent

The light dependent stage of photosynthesis takes place in the grana (stacks of thylakoids) of the chloroplasts, when light hits a chlorophyll molecule the electrons will be excited to a higher energy state where it reduces the electron carrier, the electrons…