Lecture 10: Blood Gas Transport

Question 1

Why is oxygen transport in the blood necessary for animals with high metabolic rates?
A. Oxygen is insoluble in air.
B. Solubility of oxygen in aqueous fluids is low.
C. Animals cannot absorb oxygen directly from the environment.
D. Oxygen cannot bind to hemoglobin without transport.

Answer 1

Answer: B

Question 2

What are metalloproteins also known as?
A. Hemoglobin
B. Respiratory pigments
C. Enzymatic carriers
D. Oxygen reducers

Answer 2

Answer: B

Question 3

What is the function of metalloproteins in oxygen transport?
A. They dissolve oxygen in the blood.
B. They eliminate the need for oxygen transport.
C. They increase oxygen carrying capacity by 50-fold.
D. They decrease oxygen carrying capacity to maintain balance.

Answer 3

Answer: C

Question 4

How do metalloproteins bind oxygen?
A. Through a covalent bond
B. By using metal ions that reversibly bind to oxygen
C. By permanently capturing oxygen molecules
D. By forming free radicals

Answer 4

Answer: B

Question 5

Where do metalloproteins bind oxygen in the body?
A. In the digestive system
B. At the respiratory surface
C. In the lymphatic system
D. Inside the nucleus of cells

Answer 5

Answer: B

Question 6

What effect does oxygen binding by metalloproteins have on blood PO₂?
A. It increases blood PO₂.
B. It reduces blood PO₂.
C. It has no effect on blood PO₂.
D. It eliminates blood PO₂ completely.

Answer 6

Answer: B

Question 7

Which of the following is NOT one of the three major types of respiratory pigments?
A. Hemoglobins
B. Hemocyanins
C. Hemerythrins
D. Myoglobin

Answer 7

Answer: D

Question 8

What is the primary role of respiratory pigments like hemoglobin?
A. To facilitate the elimination of carbon dioxide
B. To enhance oxygen solubility in the bloodstream
C. To provide nutrients to tissues
D. To regulate body temperature

Answer 8

Answer: B

Question 9

What happens when metalloproteins bind oxygen?
A. The oxygen gradient in blood decreases.
B. The oxygen gradient in blood increases.
C. The oxygen gradient is eliminated.
D. The oxygen gradient becomes unpredictable.

Answer 9

Answer: B

Question 10

Which of the following statements best summarizes the function of metalloproteins?
A. They provide an alternative to oxygen transport in animals.
B. They transport carbon dioxide away from tissues.
C. They increase oxygen transport capacity to meet high metabolic needs.
D. They store oxygen permanently in the bloodstream.

Answer 10

Answer: C

Question 11

Which property allows metalloproteins to increase oxygen-carrying capacity?
A. They chemically break down oxygen.
B. They bind oxygen using metal ions reversibly.
C. They store oxygen permanently in tissues.
D. They transform oxygen into water for transport.

Answer 11

Answer: B

Question 12

What is the relationship between metalloproteins and the oxygen diffusion gradient?
A. Metalloproteins decrease the diffusion gradient.
B. Metalloproteins eliminate the diffusion gradient.
C. Metalloproteins increase the diffusion gradient by reducing blood PO₂.
D. Metalloproteins stabilize the diffusion gradient.

Answer 12

Answer: C

Question 13

Which of the following is the most common respiratory pigment?
A. Hemoglobin
B. Hemocyanin
C. Hemerythrin
D. Myoglobin

Answer 13

Answer: A

Question 14

How is oxygen bound in hemoglobin?
A. To globin chains only
B. To iron in the heme group
C. Directly to globular proteins
D. As a free ion in plasma

Answer 14

Answer: B

Question 15

How many oxygen molecules can a single hemoglobin molecule bind?
A. One
B. Two
C. Four
D. Eight

Answer 15

Answer: C

Question 16

What structural feature is common to vertebrate hemoglobin?
A. Two beta and two gamma chains
B. Four globin molecules: two alpha and two beta chains
C. Only one alpha chain
D. Six globin molecules with varying compositions

Answer 16

Answer: B

Question 17

Where is hemoglobin typically found in invertebrates and vertebrates?
A. In the nucleus of red blood cells in vertebrates
B. In blood cells of vertebrates and in the circulatory fluid of invertebrates
C. In muscle cells only
D. Free-floating in the cytoplasm

Answer 17

Answer: B

Question 18

What is the primary function of myoglobin?
A. To transport oxygen in the blood
B. To serve as a reserve for oxygen in muscle cells
C. To facilitate carbon dioxide transport
D. To reduce blood pressure

Answer 18

Answer: B

Question 19

How does myoglobin differ from hemoglobin?
A. Myoglobin is tetrameric, while hemoglobin is monomeric.
B. Myoglobin is found in blood, while hemoglobin is in muscle cells.
C. Myoglobin is monomeric and found in the cytoplasm of muscle cells.
D. Myoglobin binds carbon dioxide, while hemoglobin binds oxygen.

Answer 19

Answer: C

Question 20

Which metal ion is central to the oxygen-binding capacity of hemoglobin?
A. Magnesium
B. Copper
C. Iron
D. Zinc

Answer 20

Answer: C

Question 21

What is the second most common respiratory pigment?
A. Hemoglobin
B. Hemerythrin
C. Hemocyanin
D. Myoglobin

Answer 21

Answer: C

Question 22

Which organisms primarily use hemocyanin for oxygen transport?
A. Vertebrates
B. Arthropods and molluscs
C. Amphibians
D. Reptiles

Answer 22

Answer: B

Question 23

What metal ion does hemocyanin use to bind oxygen?
A. Iron
B. Copper
C. Zinc
D. Magnesium

Answer 23

Answer: B

Question 24

What color does hemocyanin turn when oxygenated?
A. Red
B. Blue
C. Green
D. Clear

Answer 24

Answer: B

Question 25

Where is hemocyanin typically found in arthropods and molluscs? A. Blood cells B. Hemolymph C. Muscle cells D. Plasma

Answer 25

Answer: B

Question 26

What is the relationship between partial pressure of oxygen (pO₂) and oxygen saturation in hemoglobin? A. It is linear. B. It is sigmoidal due to cooperative binding. C. It is hyperbolic. D. It is logarithmic. Answer: B

Answer 26

Answer: B

Question 27

What is the significance of maintaining partial pressure in the systemic capillaries? A. To prevent oxygen loss in mitochondria. B. To drive oxygen diffusion to the mitochondria. C. To store oxygen in the bloodstream. D. To eliminate CO₂ from the body.

Answer 27

Answer: B

Question 28

Why does hemoglobin show cooperative binding to oxygen? A. To allow linear binding at low partial pressures. B. To increase efficiency of oxygen binding at higher partial pressures. C. To compete with other respiratory pigments. D. To maintain a constant oxygen saturation regardless of pO₂.

Answer 28

Answer: B

Question 29

What is P50 in the context of oxygen saturation? A. The partial pressure of oxygen at which 100% saturation is achieved B. The partial pressure of oxygen at which 50% oxygen saturation is achieved C. The time it takes for hemoglobin to release 50% of bound oxygen D. The affinity constant for oxygen binding to hemoglobin

Answer 29

Answer: B

Question 30

What does a lower P50 value indicate about hemoglobin's oxygen affinity? A. Higher oxygen affinity B. Lower oxygen affinity C. No change in oxygen affinity D. Oxygen release at higher partial pressures

Answer 30

Answer: A

Question 31

Which of the following factors could shift the oxygen dissociation curve to the right, increasing P50? A. Decrease in carbon dioxide levels B. Increase in pH (alkalosis) C. Increase in temperature D. Decrease in 2,3-BPG levels

Answer 31

Answer: C

Question 32

If the P50 value increases, what can be inferred about hemoglobin's oxygen release? A. Oxygen release is more difficult. B. Oxygen release occurs at higher partial pressures. C. Hemoglobin binds oxygen more tightly. D. Oxygen release occurs at lower partial pressures.

Answer 32

Answer: B

Question 33

How is the P50 value determined from an oxygen dissociation curve? A. By identifying the oxygen partial pressure at 75% saturation B. By finding the oxygen partial pressure corresponding to 50% saturation C. By averaging the partial pressures at 25% and 75% saturation D. By calculating the slope of the curve at 50% saturation

Answer 33

Answer: B

Question 34

What does a rightward shift in the oxygen dissociation curve indicate? A. Increased oxygen affinity B. Decreased oxygen affinity C. Decreased ability to release oxygen to tissues D. Higher oxygen saturation at lower pO₂

Answer 34

Answer: B

Question 35

In what situation might a lower P50 value be observed? A. During exercise B. In fetal hemoglobin C. At higher temperatures D. In an acidic environment

Answer 35

Answer: B

Question 36

What happens to oxygen affinity if the partial pressure of oxygen decreases below the P50 value? A. Oxygen affinity decreases rapidly. B. Oxygen affinity increases. C. There is no effect on oxygen affinity. D. Hemoglobin releases oxygen more quickly.

Answer 36

Answer: B

Question 37

Which condition would likely decrease the P50 value? A. Acidosis (low pH) B. Hypothermia (low temperature) C. Increased levels of 2,3-BPG D. Hypercapnia (high CO₂ levels)

Answer 37

Answer: B

Question 38

What does a "shift to the right" in the oxygen dissociation curve signify? A. Increased oxygen affinity B. Decreased oxygen affinity C. Oxygen binds more tightly to hemoglobin D. Lower P50 value

Answer 38

Answer: B

Question 39

Which of the following causes a "rightward shift" in the oxygen dissociation curve? A. Low pCO₂ levels B. Decrease in temperature C. Increase in 2,3-DPG concentration D. High pH

Answer 39

Answer: C

Question 40

What does a higher P50 value indicate? A. Increased oxygen affinity B. Decreased oxygen affinity C. Constant oxygen affinity D. Hemoglobin saturation is independent of pO₂

Answer 40

Answer: B

Question 41

Why does myoglobin have a lower P50 compared to hemoglobin? A. Myoglobin is tetrameric. B. Myoglobin binds oxygen more easily at low pO₂. C. Myoglobin requires high pO₂ for oxygen binding. D. Myoglobin's function is to release oxygen, not store it.

Answer 41

Answer: B

Question 42

What is the relationship between oxygen affinity and P50? A. Direct relationship: higher P50 means higher affinity. B. Inverse relationship: higher P50 means lower affinity. C. No relationship exists between P50 and affinity. D. P50 and affinity are equal under normal conditions.

Answer 42

Answer: B

Question 43

Which hemoglobin type is better suited for oxygen storage in muscle tissues? A. Myoglobin B. Fetal hemoglobin C. Adult hemoglobin D. Hemocyanin

Answer 43

Answer: A

Question 44

What structural change in hemoglobin facilitates cooperative binding? A. Transition from the relaxed (R) state to the tense (T) state B. Disruption of salt bridges after the binding of the first O₂ molecule C. Formation of salt bridges at high pO₂ D. Loss of hydrogen bonds in the globin chains

Answer 44

Answer: B

Question 45

What does the Bohr Effect describe? A. Hemoglobin's increased affinity for oxygen at low CO₂ levels B. The effect of pH and CO₂ on hemoglobin's oxygen affinity C. The cooperative binding of oxygen to hemoglobin D. The impact of temperature on hemoglobin saturation

Answer 45

Answer: B

Question 46

If blood pH decreases from 7.4 to 7.2, what happens to hemoglobin's oxygen dissociation curve? A. It shifts to the left, indicating higher affinity for oxygen. B. It shifts to the right, indicating lower affinity for oxygen. C. It remains unchanged because pH does not affect hemoglobin. D. It becomes hyperbolic, indicating a loss of cooperativity.

Answer 46

Answer: B

Question 47

A respiratory pigment has a P50 value of 2 kPa. What can you infer about its oxygen affinity? A. It has high oxygen affinity. B. It has low oxygen affinity. C. It releases oxygen readily at low pO₂. D. It has the same affinity as hemoglobin.

Answer 47

Answer: A

Question 48

Using the oxygen dissociation curve, what happens to hemoglobin saturation at a pO₂ of 40 mmHg under normal physiological conditions? A. It is almost completely saturated (~98%). B. It is around 75% saturated. C. It drops to 50% saturation. D. It remains below 20% saturation.

Answer 48

Answer: B

Question 49

In tissues with high CO₂ production, how does the Bohr Effect enhance oxygen delivery? A. By increasing hemoglobin's oxygen affinity B. By increasing pH and shifting the dissociation curve to the left C. By decreasing pH and reducing hemoglobin's oxygen affinity D. By preventing cooperative binding of oxygen

Answer 49

Answer: C

Question 50

In high-altitude environments, what adaptive shift might occur in the oxygen dissociation curve? A. Rightward shift due to increased 2,3-BPG production B. Leftward shift to enhance oxygen affinity at low pO₂ C. Hyperbolic shift to improve cooperative binding D. Flattening of the curve to stabilize oxygen levels

Answer 50

Answer: B

Question 51

Which of the following conditions would increase the P50 value of hemoglobin? A. Decreased 2,3-BPG concentration B. Increased temperature and lower pH C. Fetal hemoglobin replacing adult hemoglobin D. Hyperventilation leading to reduced CO₂ levels

Answer 51

Answer: B

Question 52

15. How does the transition from the tense (T) state to the relaxed (R) state in hemoglobin affect its oxygen affinity? A. Oxygen affinity decreases as hemoglobin moves from the T state to the R state. B. Oxygen affinity increases as hemoglobin moves from the T state to the R state. C. The transition has no effect on oxygen affinity. D. The T state has higher oxygen affinity than the R state.

Answer 52

Answer: B

Question 53

Which of the following is NOT true about cooperative binding in hemoglobin? A. It allows hemoglobin to bind oxygen more easily after the first oxygen molecule binds. B. It results in a sigmoidal oxygen dissociation curve. C. It occurs because myoglobin facilitates oxygen storage in muscle tissues. D. It involves structural changes in hemoglobin from the T state to the R state.

Answer 53

Answer: C

Question 54

What happens to hemoglobin's oxygen affinity when blood pH decreases? A. Oxygen affinity increases. B. Oxygen affinity decreases. C. Oxygen affinity remains unchanged. D. Hemoglobin becomes saturated at lower pO₂.

Answer 54

b)

Question 55

What is the physiological significance of a right shift in the oxygen dissociation curve? A. Improved oxygen loading in the lungs B. Enhanced oxygen unloading at active tissues C. Increased hemoglobin saturation in acidic environments D. Reduced oxygen delivery to tissues

Answer 55

Answer: B

Question 56

What effect does an increase in PCO₂ have on the oxygen dissociation curve? A. Shifts the curve to the left, increasing oxygen affinity B. Shifts the curve to the right, reducing oxygen affinity C. Increases hemoglobin saturation at all pO₂ levels D. Does not affect the oxygen dissociation curve

Answer 56

Answer: B

Question 57

How does an increase in body temperature affect oxygen affinity? A. Increases oxygen affinity by stabilizing hemoglobin B. Decreases oxygen affinity, promoting oxygen unloading C. Increases oxygen loading in tissues D. Has no effect on oxygen binding

Answer 57

Answer: B

Question 58

What is the function of 2,3-diphosphoglycerate (DPG) in oxygen transport? A. Increases hemoglobin's oxygen affinity B. Decreases hemoglobin's oxygen affinity to promote unloading C. Stabilizes the T state to prevent oxygen binding D. Shifts the oxygen dissociation curve to the left

Answer 58

Answer: B

Question 59

In what condition is 2,3-DPG production increased? A. Low RBC count (anemia) B. High blood pH C. Reduced body temperature D. High oxygen saturation

Answer 59

Answer: A

Question 60

Why is the Bohr Effect beneficial during exercise? A. It increases hemoglobin's oxygen affinity in tissues. B. It enhances oxygen unloading in acidic, high-CO₂ environments like muscles. C. It reduces oxygen consumption by hemoglobin. D. It increases hemoglobin saturation in the lungs.

Answer 60

Answer: B

Question 61

Which of the following scenarios would result in a left shift of the oxygen dissociation curve? A. Increased production of 2,3-DPG B. High PCO₂ levels in tissues C. Alkalosis (increased blood pH) D. High body temperature

Answer 61

Answer: C

Question 62

In an anemic individual, how does increased 2,3-DPG production help with oxygen delivery? A. It stabilizes the R state of hemoglobin, increasing oxygen affinity. B. It stabilizes the T state of hemoglobin, reducing oxygen affinity and enhancing unloading. C. It binds directly to oxygen, improving transport capacity. D. It shifts the oxygen dissociation curve to the left, improving oxygen retention.

Answer 62

Answer: B

Question 63

How does high 2,3-DPG production affect oxygen affinity in hemoglobin? A. It increases oxygen affinity, causing a left shift in the dissociation curve. B. It decreases oxygen affinity, causing a right shift in the dissociation curve. C. It stabilizes hemoglobin, reducing oxygen unloading. D. It prevents oxygen binding at low partial pressures.

Answer 63

Answer: B

Question 64

Why do high-altitude mice produce little or no 2,3-DPG? A. To enhance oxygen unloading to tissues B. To increase oxygen extraction from the lungs at high altitudes C. To promote anemia adaptation D. To reduce oxygen binding at low pO₂

Answer 64

Answer: B

Question 65

What is the physiological advantage of a hyperbolic oxygen dissociation curve in high-altitude mice? A. Easier oxygen unloading in tissues B. Greater oxygen loading in the lungs despite low pO₂ C. Increased oxygen saturation at normal pO₂ D. Stabilized hemoglobin under acidic conditions

Answer 65

Answer: B

Question 66

What happens to the oxygen dissociation curve in humans acclimated to high altitudes? A. It shifts to the left to improve oxygen loading at low pO₂. B. It shifts to the right due to increased 2,3-DPG production. C. It becomes hyperbolic, similar to high-altitude mice. D. It remains unchanged as humans cannot adapt to high altitudes.

Answer 66

Answer: B

Question 67

What is a potential disadvantage of low 2,3-DPG production in high-altitude mice? A. Reduced oxygen extraction in the lungs B. Difficulty in oxygen unloading at tissues C. Higher P50 values in the lungs D. Increased oxygen delivery to inactive tissues

Answer 67

Answer: B

Question 68

Compare the oxygen affinity adaptations in high-altitude mice and humans. What are the advantages and disadvantages of these adaptations for oxygen transport at high altitudes?

Answer 68

High-altitude mice exhibit a hyperbolic oxygen dissociation curve due to low or no 2,3-DPG production. This allows them to extract oxygen more effectively in their lungs, even at low partial pressures, which is critical for survival at high altitudes. However, the disadvantage is that oxygen unloading at tissues is reduced, potentially impairing oxygen delivery to actively metabolizing tissues. In humans, high-altitude acclimation is characterized by increased 2,3-DPG production, which shifts the oxygen dissociation curve to the right. This reduces hemoglobin's oxygen affinity, improving oxygen unloading at tissues. The disadvantage is slightly reduced oxygen loading efficiency in the lungs compared to normal conditions, but this is offset by the higher altitude's lower pO₂.

Question 69

Why does the human body produce more 2,3-DPG at high altitudes? A. To increase oxygen affinity of hemoglobin B. To decrease oxygen affinity and enhance oxygen unloading at tissues C. To improve oxygen extraction from the lungs D. To reduce the production of red blood cells

Answer 69

Answer: B

Question 70

What is a disadvantage of 2,3-DPG production at high altitudes? A. Reduced oxygen loading at low partial pressures B. Increased oxygen binding in tissues C. Excessive red blood cell production D. Decreased oxygen unloading in tissues

Answer 70

Answer: A

Question 71

What is the role of increased red blood cell production at high altitudes? A. To increase oxygen delivery to tissues B. To improve oxygen saturation at low pO₂ C. To reduce oxygen affinity in hemoglobin D. To enhance oxygen unloading at higher temperatures

Answer 71

Answer: A

Question 72

How does the sigmoidal oxygen dissociation curve in humans benefit them at high altitudes? A. Promotes oxygen unloading at tissues and loading at the lungs B. Increases oxygen affinity for all partial pressures C. Prevents oxygen release to inactive tissues D. Improves cooperative binding at low pO₂

Answer 72

Answer: A

Question 73

What causes high-altitude pulmonary edema (HAPE)? A. Decreased oxygen diffusion in the lungs B. Constriction of pulmonary blood vessels due to low oxygen C. Increased oxygen affinity of hemoglobin D. Decreased blood pressure in pulmonary capillaries

Answer 73

Answer: B

Question 74

Which of the following is the most severe consequence of high-altitude exposure? A. Hyperventilation B. High-altitude pulmonary edema (HAPE) C. High-altitude cerebral edema (HACE) D. Increased 2,3-DPG production

Answer 74

Answer: C

Question 75

What physiological change helps the body adapt to reduced oxygen levels at high altitudes? A. Decreased production of 2,3-DPG B. Increased constriction of systemic blood vessels C. Increased red blood cell production and hemoglobin concentration D. Reduced hemoglobin-oxygen saturation

Answer 75

Answer: C

Question 76

How does the pulmonary circuit normally prevent fluid buildup? A. By maintaining low pressure and high compliance B. By constricting blood vessels to increase pressure C. By increasing oxygen affinity in hemoglobin D. By reducing the production of red blood cells

Answer 76

Answer: A