Limiting Factors In Photosynthesis Flashcards
What makes carbon dioxide the limiting factor?
As concentration increases, the rate of the light independent stage increases, so photosynthesis increases, therefore it is the limiting factor.
Why does rate of photosynthesis decrease at 1% CO2 concentration?
Because stomata close.
Where do aquatic plants get CO2 from and how does algae stop CO2 being a limiting factor?
They get it from the CO2 in HCO3- ions. Algae increase carbon dioxide concentration with carbonic anhydrase.
What is the rate limiting step? Give an example.
The rate of the slowest reaction in a process determines the overall rate of a process. For example with the light independent reaction in relation to CO2 concentration, the reaction catalysed by rubisco is the rate limiting step.
How is light intensity a rate limiting factor?
As light intensity increases, so does the rate of photosynthesis.
What are the implications of light intensity on photosynthesis?
At approximately 10,000 lux the rate stays constant. Higher than this bleaches the chloroplasts, so they can’t absorb light so rate decreases.
What is the light compensation point?
At a particular light intensity, so little CO2 is needed that respiration provides all that is required and none is absorbed. Similarly all O2 needed for respiration is provided by photosynthesis. This means there is no net gas exchange. This is the light compensation point.
Explain how temperature can be a limiting factor for photosynthesis
Increased temperature increases rate because the kinetic energy of molecules involved increases. Above a certain temperature, enzymes denature so rate decreases.
How can water be a rate limiting factor?
When water is scarce, cells plasmolyse, stomata close, wilting occurs and many physical functions are affected.
