(a) C4 plant is a plant in which the CO2 is first fixed into a compound containing four carbon atoms before entering the Calvin cycle of photosynthesis. Example of C4 plants are maize and sugarcane.
(b) Both C3 and C4 plants open their stomata during daylight, when both light and dark reactions takes place. Both plants absorb carbon in non-acidic form. Both plants use RuBisCO during their photosynthetic process. The leaves of a C4 plants have a special anatomy called Kranz anatomy. This makes them different from C3 plants. Special cells, known as bundle sheath cells, surround the vascular bundles. These cells have a large number of chloroplasts. They are thick walled and have no intercellular spaces. They are also impervious to gaseous exchange. All these anatomical features help prevent photorespiration in C4 plants, thereby increasing their ability to photosynthesize.
