5.2.6 - Rate Limiting Factors Flashcards
What is the compensation point in plants?
When CO2 produced by respiration is equal to CO2 taken up by plants for photosynthesis.
Why does the concentration of Glycerate-3-phosphate increase in dim light?
Less NADPH produced in light dependent reaction so GP is not reduced to TP
Name some external rate limiting factors of photosynthesis.
Light intensity
Light wavelength
Wind speed
Name some internal rate limiting factors of photosynthesis.
Concentration of photosynthetic pigments
Enzyme and water content
Why does concentration of RUBP in the Calvin cycle decrease at a higher CO2 concentration?
It is continuously combining with CO2 to form glycerate-3-phosphate.
What happens first in Crassulacean Acid Metabolism?
Stomata opens when its cooler so CO2 diffuses into leaf.
CO2 is converted into a 4 carbon compound called Malic acid
What is the name of the compound that converts CO2 into Malic acid in the crassulacean acid metabolism?
Phosphoenolpyruvate Carboxylase.
(PEP carboxylase)
Where is the Malic acid produced in the crassulacean acid metabolism stored?
The cytoplasm of mesophyll cells
What happens to malic acid at the end of the crassulacean acid metabolism?
It’s decarboxylated so CO2 is released which can be used in photosynthesis
Why do some plants use the crassulacean acid metabolism?
Stomatal closure during the day to prevent water loss limit the availability of CO2 when light intensity is highest so rate of photosynthesis in affected.
Some plants are adapted to hot and dry conditions so an alternative pathway to produce CO2 for photosynthesis is needed.
Why does increasing the concentration of CO2 increase the rate of photosynthesis?
The enzyme Rubisco’s activity increases. There are more succesful enzyme-substrate collisions.
Why does a higher light intensity increase the rate of photosynthesis?
More light photons strike PS1 and PS2.
More excited electrons are transferred down electron carriers so more ATP and NADPH produced for Calvin cyle.
Why does increasing temperature increase the rate of photosynthesis?
Rubisco has more kinetic energy so more succesful collisions with CO2 and ribulose bisphosphate.
