Sunlight powers the planet and photosynthesis converts this solar energy into energy that plants transfer into the food chain. Photosynthesis provides plants with sugars and plant proteins that are important for animals as well as human agriculture. Most people know the general idea behind it, but there are many complex processes that make up the entirety of photosynthesis. Different aspects of photosynthesis, photosystems and photosynthetic pathways are still studied today because not everything is known about how they work and function. There are three different chemical pathways by which photosynthesis can occur: C3, C4, and crassulacean acid metabolism (CAM). ). These pathways occur during the Calvin cycle of photosynthesis. The CAM pathway evolved in plants living in arid conditions, but the C3 and C4 pathways can coexist in many different environments. What's interesting about these two pathways is that the C4 pathway appears to be more efficient at producing sugars and fixing carbon than the C3 pathway. Why then does the C3 route remain the most common when it does not seem to be as reliable or effective? Are these plants still transitioning to a more advanced chemical pathway or are there other benefits to being a C3 plant that outweigh the sugar production efficiency found in the C4 pathway? The C3 pathway would have been most useful in the early days of the planet. . Until the evolution of photosynthesis, oxygen was not common in Earth's atmosphere. Oxygen can and will enter the plant system during the light-independent part of photosynthesis, the Calvin cycle, and instead of the first fixed carbon compound being a three-carbon molecule, it will produce a two-carbon molecule. carbons...... .middle of paper......pathways have their place in their own environment. One is not definitively better than the other. Both paths have their advantages and disadvantages. Although the C4 pathway may be more effective than the C3 pathway under ideal conditions, these ideal conditions cannot always be met. Nature does not create these conditions, nor can farmers provide these conditions all the time, even in controlled environments like a greenhouse. The costs may exceed the benefits in the long term. Efficiency comes at the cost of increased energy use to circumvent photorespiration and a failure, thus far, to adapt to global climate change. Further research can be conducted to investigate the possibility of using effective C4 enzymes in C3 plants without having to worry about climate change or atmospheric carbon levels. Perhaps research could also be done to look at energy usage in both types of pathways..