Where in cells does most of cellular respiration take place?

Mitochondrion

Explanation:

The enzymatic reactions of cellular respiration begin in the cytoplasm, but most of the reactions occur in the mitochondria. Cellular respiration occurs in the double-membrane organelle called the mitochondrion. The folds in the inner membrane are called cristae.

Explanation:

The mitochondrion is a double membrane-bound organelle found in most eukaryotic organisms. Some cells in some multicellular organisms lack mitochondria. A number of unicellular organisms, such as microsporidia, parabasalids, and diplomonads, have reduced or transformed their mitochondria into other structures.

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