Why doesn't an animal cell need to photosynthesize in order for cellular respiration to occur

Hi!

In order for cellular respiration to occur in a cell, the cell needs to have glucose molecules to utilize in the reaction which is as follows:

C6H12O6 + 6 O2  -->  6 CO2  + 6 H2O + ATP (energy)

Cellular respiration cannot occur in the absence of glucose. Plant cells acquire this glucose from photosynthesis:

6CO2 + 6H2O + light energy = C6H12O6 + 6O2

Animal cells do not need to photsynthesize because they acquire the amount of  glucose for cellular reaction from their diet/consumption. Herbivores acquire this glucose from plants, carnivores from feeding off other animals, and omnivores from both feeding off plants and animals.

Hope this helps!

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.