Which by-product of cellular respiration is used by autotrophs to produce glucose?

The by-product of cellular respiration that is used by autotrophs to produce glucose is carbon dioxide. During cellular respiration, organisms break down glucose to produce energy in the form of ATP, and carbon dioxide is released as a waste product. Autotrophs, such as plants, utilize this carbon dioxide during the process of photosynthesis. In photosynthesis, carbon dioxide is combined with water in the presence of sunlight to synthesize glucose and oxygen. This cycle highlights the interdependence of autotrophs and heterotrophs in ecosystems, where the carbon dioxide produced by one group becomes an essential resource for the other.

In contrast, the other options play different roles: ATP is the energy currency produced during respiration but is not a by-product used in glucose production. Chlorophyll is a pigment in plants necessary for photosynthesis but does not derive from cellular respiration processes. Oxygen, while produced as a by-product of photosynthesis, is not utilized by autotrophs for glucose synthesis.