Factors that affect the rate of photosynthesis
- The rate of photosynthesis is usually measured as the amount of oxygen produced or carbon dioxide used up in a given time.
- Temperature - The rate of photosynthesis increase with increase in temperature up to the optimum. Above optimum, heat energy denatures enzyme so the rate falls until all enzymes are denatured and the activity stops.
- Carbon dioxide concentration - Rate of photosynthesis increase with increase C02 concentration to a point where rate levels off as some other factor becomes limiting.
- Light intensity - Rate of photosynthesis increase with increase in light intensity up to a point where some other factor becomes limiting or energy in light damages the leaf.
- Wavelength of light - Wavelength in violet, indigo and red are absorbed in greater amounts so rate increases. wavelength in green yellow and orange are not absorbed as much result in a lower rate
- Leaf adaptations - Leaves that are adapted to photosynthesise best in low light intensity are called 'shade leaves'. Shade leaves are thinner have a greater surface area and their cells contain more chlorophyll than 'sun leaves' Rate of photosynthesis in shade leaves is higher at low light intensities whereas leaves adapted to high light intensity have a higher rate of photosynthesis in higher light intensities.
- water content - lack of water wilts plants and close stomata that prevents diffusion of CO2.
- lack of magnesium ions reduce production of chloropyll.
- Lack of enzymes and enery carriers (ATP/NADPH) can also limit rate.
- Because temperature, light intensity and carbon dioxide combine to determine rate of photosynthesis, the maximum rate can alter if one of the other factors change.
