Question 40 Answer and Explanation _ACT April 2005 Form 60E Science Section

Passage VII

The amount of O₂ present in blood and tissues can be measured, in mm Hg, as the partial pressure of O₂ ( ${P}_{{O}_{2}}$ ). The percent saturation of Hb is the percent of hemoglobin in the blood that is bound with O₂. Figure 1 shows the relationship between percent saturation of Hb and , at normal body conditions.

Figure 2 shows the relationship between percent saturation of Hb and , at different pHs. The pH of blood is affected by the partial pressure of CO₂ ().

Figure 3 shows the relationship between percent saturation of Hb and , at different blood temperatures.

Figures adapted from Robert Carola, John P. Harley, and Charles R. Noback, Human Anatomy and Physiology. ©1990 by McGraw-Hill, Inc.

40. Based on the data in Figure 2, which of the following statements best explains why ${P}_{{O}_{2}}$ affects the pH of blood? When CO₂ dissolves in blood, it:

F. forms an acid.

G. absorbs acids.

H. breaks down to form O₂.

J. reacts with O₂ to form Hb.

Answer and Explanation

Your Answer is

Correct Answer is F

Explanation

General knowledge questions.

CO₂ dissolves in water to produce carbonic acid H₂CO₃