C4: corn, sorghum, sugar cane — tropics CAM: cacti, aloe — desert (b) (1 pts) Which carbon-fixing enzyme occurs in both C4 and CAM plants (but not in C3 plants)? PEP carboxylase (c) (2 pts) How do C4 plants use malate? How do CAM plants use malate? C4: to transport fixed CO2 from mesophyll cells to the bundle sheath cells (where it is released) CAM: to store fixed CO2 in the vacuole at night for release during the day (d) (2 pts) Are C4 plants or CAM plants more efficient water-savers? Why?