Question

which pathway adds carbon dioxide back to the atmosphere from living organisms?
aerobic cellular respiration
feeding
photosynthesis by plants and algae
fossilization

Explanation:

Aerobic cellular respiration is a metabolic process in which living organisms (including animals, plants, fungi, and many bacteria) break down glucose (or other organic molecules) in the presence of oxygen. The chemical equation for aerobic cellular respiration is \(C_6H_{12}O_6+6O_2
ightarrow6CO_2 + 6H_2O+\text{energy}\). As shown in the equation, carbon - dioxide (\(CO_2\)) is a by - product of this process and is released back into the atmosphere.

Feeding is a process where one organism consumes another (or organic matter) to obtain nutrients. It does not directly add \(CO_2\) to the atmosphere from living organisms.

Photosynthesis by plants and algae is the process of taking in \(CO_2\) from the atmosphere (along with water) and using light energy to produce glucose (\(C_6H_{12}O_6\)) and oxygen (\(O_2\)). The equation is \(6CO_2+6H_2O
ightarrow C_6H_{12}O_6 + 6O_2\). So, it removes \(CO_2\) from the atmosphere.

Fossilization is the process of organic matter (from dead organisms) being converted into fossils over long periods (e.g., coal, oil, natural gas). It does not add \(CO_2\) back to the atmosphere from living organisms in the short - term (the \(CO_2\) release from fossil fuels is due to human combustion, not the natural fossilization process from living organisms in the present).

Answer:

Aerobic cellular respiration