What is the basis for designating C3 and C4 pathways of photosynthesis?
In the C3 pathway, carbon is fixed into 3-PGA, which is a 3- 3-carbon compound. However, in the C4 pathway, carbon is fixed into oxaloacetic acid, which is a 4-carbon compound. Hence, the C3 and C4 pathways are designated based on the carbon compound number in the end product.