Factors Affecting the Rate of Photosynthesis
- The rate of photosynthesis is affected by the availability of its raw materials, and by the energy required for chemical reactions to occur
- The following factors therefore affect the rate of photosynthesis:
- Light intensity
- Carbon dioxide concentration
- Temperature
- Note that while water is a raw material in photosynthesis, it is involved in multiple plant processes, so its effects on photosynthesis are complex and are not covered here
Light intensity
- As light intensity increases, the rate of photosynthesis will also increase
- This is because photosynthesis is a chemical reaction that requires light energy, so when less light energy is available, the reaction occurs at a reduced rate
Carbon dioxide concentration
- As carbon dioxide concentration increases, so does the rate of photosynthesis
- This is because carbon dioxide is a reactant in photosynthesis, so reducing its availability will reduce the rate at which the reaction can proceed
Temperature
- The temperature at which photosynthesis occurs is important because photosynthesis, like many chemical reactions inside living cells, is controlled by enzymes, and temperature affects the rate of enzyme-controlled reactions
- As temperature increases, the rate of photosynthesis increases, up to a point
- More energy is available for the movement and collision of molecules at higher temperatures
- It can be said that molecules have more kinetic energy at high temperatures
- At high temperatures, the rate of photosynthesis decreases, and may reach zero
- At extreme temperatures the specific shape that is essential to enzyme function is lost as chemical bonds inside the enzyme break; this is denaturation, and causes reaction rate to decrease and eventually stop altogether
