describe how carbon dioxide produced by respiring mesophyll cells of flowering plants reaches the atmosphere

Gas exchange happens in the spongy mesophyll tissue of the leaf. Spongy mesophyll cells are covered by a thin layer of water and loosely packed. When the plant is photosynthesising during the day, these features allow carbon dioxide to diffuse into the spongy mesophyll cells, and oxygen to diffuse out of it.

a. the production of carbon dioxide through the process of photosynthesis

not sure if this is what you'r looking for eubacteria and archaebacteria