Interactions of Limiting Factors
Higher tier only
- More than one limiting factor can have an effect on the rate of photosynthesis
- Graphs may show the effect of two factors interacting:
The rate of photosynthesis increases with increasing light intensity, temperature and carbon dioxide
At the start of the graph, the rate of photosynthesis is limited by the light intensity so both lines are showing the same rate.
As the light intensity increases the rate of photosynthesis at 15℃ is lower than 25℃.
Both lines level off, this shows that light intensity is no longer the limiting factor.
- Graphs may show the interactions between three different factors, the graph below shows the relationship between temperature, carbon dioxide as light intensity is increased:
The rate of photosynthesis increases with increasing light intensity, temperature and carbon dioxide
All three experiments level off when light intensity is no longer the limiting factor.
In the top line, this has the highest temperature and concentration of carbon dioxide so the rate of photosynthesis is much higher.
In experiment 2, the concentration of carbon dioxide is the limiting factor.
In this graph, the rate of photosynthesis is controlled by carbon dioxide levels.