Researchers studied the relationship between glucose concentration, oxygen level, and ATP production in one type of mammalian cell. Cells were isolated and cultured in growth medium containing either 1.5mM glucose or 25 mM glucose and at oxygen levels that varied from 0% to 21%. The researchers determined the concentration of ATP per cell under the different conditions. The ATP concentrations are shown as relative to the maximum ATP concentration obtained when cells were cultured in the presence of 25 mM glucose and 21% oxygen, standard culture conditions. The data are shown in Table 1.