C3, C4, CAM

C3

This is the most common one in most plants. In C3, the initial fixation of carbon occurs through the Calvin cycle enzyme, rubisco, that adds CO2 to ribulose biphosphate. These are given their name because the first organic product of carbon fixation is a three-carbon compound, 3-phosphoglycerate. These plants change according to their environment. During hot, dry days, they produce less food because they close their stomatas.

C4
In C4 plants, they form a four-carbon compound as its first product. About several thousand species use this method of photosynthesis including sugarcane and cane. These plants have a unique lead anatomy which is made for the purpose of the C4 pathway. They have two types of photosynthetic cells which are the bundle-sheath cells and mesophyll cells. The bundle- sheath cells are arranged into tightly packed sheaths around the veins of the leaf which the mesophyll cells are arranged loosely between the bundle sheath and the leaf surface. Similar to the C3 plants, their stomatas are open during the day. But C4 plants use PEP Carboxylase for the enzyme involved in the uptake of CO2. This enzyme allows CO2 to be taken into the plant very quickly, and then it "delivers" the CO2 directly to rubisco for photsynthesis.

CAM
Something very unique about these plants compared to all the other plants is that they open their stomatas during the night but close them during the day.The helps the desert plants conserve water while also preventing CO2 from entering the leaves. But when they do open their stomatas at night, they take up CO2 and incorporate it into a variety of organic acids. During the day, the acid is broken down and the CO2 is released to rubisco for photosynthesis