Plant and animal respiration primarily occurs in the biosphere, which is the global sum of all ecosystems. It includes all living organisms (plants, animals, microorganisms) and their interactions with each other and their environments.
During respiration, plants and animals take in oxygen (from the atmosphere) and release carbon dioxide, which is used in photosynthesis by plants. While the processes are influenced by components of the lithosphere (earth), atmosphere (air), and hydrosphere (water), the act of respiration itself is a biological process that takes place within the biosphere.
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