(SBI4U1) C4 and CAM plants Flashcards
What are the two distinct types of photosynthesis cells in C4 Plants?
Bundle-sheath cells
Mesophyll cells
How are photosynthesis cells in C4 plants arranged? (2)
Bundle-sheath cells are arranged into tightly packed sheaths around the veins of the leaf
Mesophyll cells are more loosely arranged between the bundle sheath and the leaf surface
What is the enzyme only present in mesophyll cells?
PEP carboxylase
Why is PEP carboxylase used instead of Rubisco?
PEP carboxylase has a much higher affinity for CO2 than Rubisco, and no affinity for oxygen, thus can fix carbon efficiently whereas Rubisco cannot
What does PEP carboxylase do?
Adds CO2 to phosphoenolpyruvate (PEP), forming the four-carbon product oxaloacetate
What happens when the four-carbon compounds enter the bundle-sheath cells?
They release carbon dioxide into the Calvin Cycle and regenerates pyruvate
What happens to the pyruvate regenerated in the bundle-sheath cells?
Transported to the mesophyll cells
How is pyruvate converted to PEP in the mesophyll?
Additional ATP is used
How do bundle-sheath cells generate the extra ATP required to converted pyruvate to PEP?
The bundle-sheath cells carry out cyclic electron flow
What is distinct in CAM plants that isn’t present in C4 plants?
Stomata open at night and close during the day
What happens when CAM plants open their stomata at night?
CO2 is taken in and incorporated into a variety of organic acids
What does CAM stand for?
Crassulacean Acid Metabolism
