Limiting Factors- SBIT Lab

3 Limiting factors that impact the rate of photosynthesis

• Temperature

• light intensity

• CO₂ concentration

Light intensity

Initially, increase of light intensity causes an increase in rate of photosynthesis.

Eventually a maximum rate(V max) is reached and rate of photosynthesis plateaus (everything is working at optimum)

CO₂ concentration

CO₂ is a reactant/substrate for Rubisco

Initially increase in CO₂ concentration cause increase in rate of photosynthesis.

Eventually a maximum rate is reached and the rate of photosynthesis plateaus

Temperature

Initially an increase in temp causes increase in rate of photosynthesis because of # of collisions increases

then above the optimum temperature the rate drops due to enzyme denaturation

• enzymes in photosynthesis ex) rubisco

Why scientists conduct CO₂ enrichment experiments

• CO₂ concentration are rising due to human activity

• They were curious about how plants are going to respond to increased levels of CO₂

Greenhouses manipulated CO₂ concentrations

• increase CO₂ concentration in a green house

• able to measure biomass compared to a control group

• Pros: more control over experiment

• Cons: “artificial“ environment (might act differently than normal)

Free-air carbon dioxide enrichment experiments(FACE)

• Pipes pump CO₂ into the atmosphere

• Sensors monitor CO₂ levels

• Pros: carried out in a natural ecosystem

• Cons: Expensive and harder to control