AQA GCSE Limiting factors interacting (Biology)
Limiting factors interacting
Make sure you have read through the page on single limiting factors first, it can be found here.
A limiting factor is a factor that is in short supply, increasing the limiting factors will increase the rate of photosynthesis.
There are four limiting factors for photosynthesis
1.Temperature
2.Carbon dioxide concentration
3. Light intensity
4. Amount of chlorophyll
Photosynthesis depends on all factors at the same time. Increasing one factor only increases the rate if the others are not limiting.
Changing one factor can change which factor is limiting
Two-factor graphs
On the graph below each line shows how rate of photosynthesis changes with light intensity at a specific CO₂ concentration.
Differences between the lines show the effect of CO₂ concentration on the rate of photosynthesis.
Low CO₂ line (0.01%):
Red part of graph rate plateaus at higher light intensity so CO₂ is limiting factor and light intensity is not a limiting factor.
High CO₂ line (0.04%):
Green part of graph rate increases at low light intensity so light is limiting factor.
Red part of graph rate plateaus at higher light intensity so both light intensity and carbon dioxide are no longer limiting factors, another factor is possibly limiting e.g. temperature. intensity is not a limiting factor.
Compare the two lines
At low light intensity: both lines are close, so light is limiting factors, CO₂ concentration effect is small.
At higher light intensity: lines diverge so a change in carbon dioxide concentration has a bigger effect.
Show that changing CO₂ changes the plateau
Three-factor graphs
Practice Questions
1.