6-6 Comparing C3, C4 and CAM Photosynthesis

What other molecule often diffuses OUT of the stomata?

• glucose

• H₂O

Notice the diagram.  The CO₂ is actually "fixed" twice. First in the mesophyll cell by PEP carboxylase into a 4-carbon molecule.  The 4-C molecule is then broken down, releasing CO₂ into the bundle sheath cells.  Here, Rubisco binds the CO₂ and the Calvin Cycle proceeds like normal.

What type of molecules are PEP carboxylase and Rubisco? (CHECK ALL THAT APPLY)

• sugars

• enzymes

• intermediates

• proteins

Which enzyme "fixes" carbon during C3 photosynthesis?

• Rubisco

• PEP carboxylase

Which describes the order of enzymes used in carbon fixation during C4 and CAM photosynthesis?

• PEP carboxylase first, then Rubisco

• Rubisco first, then PEP carboxylase

What is the main difference between C4 and CAM photosynthesis?

• They use different enzymes.

• C4 plants fix carbon in different locations in the leaf while CAM plants fix carbon at different times

• CAM plants fix carbon in different locations in the leaf while C4 plants fix carbon at different times