At rest, the partial pressure of oxygen (PO2) is most veins is approx. 40 mm Hg. At this PO2, approx. ______ of hemoglobin molecules are associated with oxygen.
A. 25%
B. 40%
C. 50%
D. 75%
Answer: D. 75%
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Oxidation
A) involves the removal of oxygen atoms. B) is endothermic. C) occurs when an atom accepts electrons. D) occurs when oxygen is added and energy released. E) both choices B and C
The pulmonary vein carries blood that is rich in oxygen back to the heart. Is there anything unexpected about the name of this vein?
A. Veins usually carry blood that has been depleted of oxygen. B. There is nothing unexpected about the name of this vein. C. Pulmonary refers to veins that carry blood to the lungs. D. Veins usually carry blood away from the heart.
Over time, how do skeletal muscle cells respond to regular weight-lifting exercise?
A) They get larger, making the overall muscle bigger. B) They multiply, making the overall muscle bigger. C) They are able to contract for longer periods of time. D) They contain more actin and less myosin.
Which of the following statements about the function of flowers is TRUE?
A) They provide nutrients to the embryo. B) They protect seeds until they are mature. C) They attract seed dispersers. D) They aid in the dispersal of seeds. E) They attract pollinators.