C4 vs CAM Plants
Just like animals, plants also have their own coping mechanisms that allow them to survive in varying environmental conditions; but some are more adept than others. C4 and CAM plants are no like most plants, which are categorized as C3 plants, because they are more adapted to live in hotter environments where water is not readily available. The main difference between C4 and CAM plants is the way they minimize water loss. C4 plants relocate the CO2 molecules to minimize photorespiration while CAM plants choose when to extract CO2 from the environment.
Photorespiration is a process that occurs in plants where oxygen is added to RuBP instead of CO2. This occurs when oxygen levels are very high and reduces the overall efficiency of photosynthesis. C4 plants avoid this by moving the CO2 molecules into the sheath bundles (a structure unique to C4 plants) where CO2 concentration is considerably much higher than oxygen. This is where the Calvin cycle occurs where the efficiency is very high.
CAM (Crassulacean Acid Metabolism) plants have a very different but more effective approach to conserving water. They collect CO2 at night when the environment is much cooler and stores the concentrated CO2 as malate. This is then released back during the day and is consumed for photosynthesis. This process allows CAM plants to keep their stomata closed during the day where water evaporation is more likely due to the heat.
C4 plants are typically summer plants like corn and sugar cane. They can sustain high heat and reduced water supply to some extent. On the other hand, CAM plants are better suited for arid environments like deserts. Cacti and aloe vera are two CAM plants. It is usual for CAM plants to store water so that it doesn’t dry up even if rain doesn’t come for months. You can see this for yourself by breaking off a leaf or part of its trunk. Before you even attempt to squeeze it, a liquid would start to ooze of it. C4 plants do not have this much liquid stored on it as it doesn’t thrive in very dry areas.
Summary:
1.C4 plants choose where the Calvin cycle occurs while CAM plants choose when to extract CO2
2.CAM plants can survive in areas where C4 plants cannot
3.CAM plants typically have water inside them while C4 plants don’t