Read each question carefully. Write your response in the space provided for each part of each question. Answers must be written out in paragraph form. Outlines, bulleted lists, or diagrams alone are not acceptable and will not be scored.

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.

(a) ?Describe the role of oxygen in cellular respiration.

(b) Using the template, ?construct an appropriately labeled graph to represent the data in Table 1.

(c) ?Describe the relationship between the concentration of glucose in the culture medium and the ?ATP concentration in the cells.

(d) In a further experiment, the researchers add a compound to the cell growth medium that both binds and releases protons ?(H+) and also passes through lipid membranes. ?Predict the effect of this added compound on ?ATP production by the cells. ?Justify your prediction.

Table 1. Relative concentration of ATP per cell under different growth conditions Relative Concentration of ATP per Cell 0.3 0.65 0.75 0.85 0.4 0.7 0.8 1.0 Concentration of Glucose in Growth Medium 1.5 mM 1.5 MM 1.5 mM 1.5 MM 25 mM 25 mM 25 mM 25 mM Percent of Oxygen 0 5 10 21 0 5 10 21