High energy electrons are passed through the electron chain and the energy is used to split molecules of water (H2O) into their component hydrogen and oxygen. The oxygen is released as a by-product into the atmosphere. The energy released by breaking the chemical bonds in the water is incorporated, with the hydrogen, into energy carrying molecules called ATP and NADPH2.
If a process is influenced by more than one factor, the rate of the process will be limited by the factor that is in lowest supply
Therefore if temperature is low (10 °C) increasing light intensity or carbon dioxide concentration will not increase the rate of photosynthesis.
Why does this matter ? The slower the rate of photosynthesis the slower the rate of growth.
plateau At low CO 2 concentration, rate is positively correlated with concentration CO 2 is a substrate in an enyme-catalysed light-dependent reaction.
At low light intensity, rate of photosynthesis is proportional to light intensity. plateau
Increased temp. gives increased energy and increased rate of photosynthesis Optimum temperature Above the optimum temp., enzymes are denatured and rate drops steeply. Which enzymes are used in respiration?