The Latin verb supponere, meaning substitute, has several legitimate heirs in English, including supposititious (which dates from the early 17th century) and supposition (a 15th century addition).
Cellular respiration takes place in the organelles called mitochondria. The mitochondria take in glucose, a type of sugar, and change it in the presence of oxygen into an energy-rich molecule called ATP, or adenosine triphosphate. For every molecule of glucose, 36 molecules of ATP are made.
The Process. Aerobic cellular respiration occurs mainly in eukaryotic cells. These are cells that contain a nucleus (brain of the cell) and organelles (little organs that each have their own job inside the cell).