NURS 5315 TEST 3 2025/2026|UTA NURS 5315 EXAM
3|140QS&AS|A+GRADE
What is the main reason for the sigmoidal shape of the oxygen-hemoglobin
dissociation curve?
A. Independent oxygen binding to hemoglobin
B. Hemoglobin saturation being fixed at 50%
C. Cooperative binding of oxygen molecules to hemoglobin
D. Linear increase in oxygen-binding with rising pO2
C. Cooperative binding of oxygen molecules to hemoglobin
Rationale: The sigmoidal shape results from cooperative binding. When one
oxygen molecule binds to hemoglobin, it increases the affinity for subsequent
oxygen molecules.
In which part of the oxygen-hemoglobin dissociation curve does hemoglobin have
the highest oxygen saturation?
A. Left side (low pO2)
B. Flat portion at the right (high pO2)
C. Steep portion (moderate pO2)
D. Middle portion of the curve
B. Flat portion at the right (high pO2)
,Rationale: The flat portion of the curve represents high pO2 conditions, such as in
the lungs, where hemoglobin is almost fully saturated with oxygen (~100%
saturation).
What is the clinical significance of the steep portion of the oxygen-hemoglobin
dissociation curve?
A. Minimal oxygen release at tissues
B. Enhanced oxygen uptake in the lungs
C. Large oxygen release with small pO2 changes
D. No oxygen release despite low pO2
C. Large oxygen release with small pO2 changes
Rationale: The steep portion allows for significant oxygen release from
hemoglobin in response to small drops in pO2, facilitating oxygen delivery to
actively metabolizing tissues.
Which factor causes a rightward shift in the oxygen-hemoglobin dissociation
curve?
A. Decreased temperature
B. Increased pH
C. Increased 2,3-BPG
D. Hypocapnia
C. Increased 2,3-BPG
,Rationale: Increased 2,3-BPG production lowers hemoglobin's affinity for
oxygen, shifting the curve to the right and promoting oxygen unloading to
tissues.
What happens during a leftward shift of the oxygen-hemoglobin dissociation
curve?
A. Easier oxygen release at tissues
B. Increased hemoglobin affinity for oxygen
C. Higher CO2 levels
D. Acidosis
B. Increased hemoglobin affinity for oxygen
Rationale: A leftward shift means that hemoglobin binds oxygen more tightly,
reducing oxygen release to tissues but enhancing oxygen loading in the lungs.
Which of the following conditions is likely to cause a leftward shift of the curve?
A. Fever
B. Alkalosis
C. Hypercapnia
D. Increased 2,3-BPG
B. Alkalosis
, Rationale: Alkalosis (higher pH) increases hemoglobin's affinity for oxygen,
causing a leftward shift in the oxygen-hemoglobin dissociation curve.
What is the role of 2,3-Bisphosphoglycerate (2,3-BPG) in oxygen transport?
A. Enhances oxygen loading in the lungs
B. Stabilizes deoxygenated hemoglobin, promoting oxygen release
C. Shifts the curve to the left
D. Reduces oxygen delivery to tissues
B. Stabilizes deoxygenated hemoglobin, promoting oxygen release
Rationale: 2,3-BPG binds to deoxygenated hemoglobin, reducing its oxygen
affinity and facilitating oxygen release at the tissue level, causing a rightward
shift.
How does carbon monoxide (CO) poisoning affect the oxygen-hemoglobin
dissociation curve?
A. Shifts the curve to the right
B. No effect on the curve
C. Shifts the curve to the left, inhibiting oxygen release
D. Increases hemoglobin saturation
C. Shifts the curve to the left, inhibiting oxygen release
Rationale: CO binds with high affinity to hemoglobin, preventing oxygen binding
and shifting the curve to the left, which reduces oxygen release to tissues.
3|140QS&AS|A+GRADE
What is the main reason for the sigmoidal shape of the oxygen-hemoglobin
dissociation curve?
A. Independent oxygen binding to hemoglobin
B. Hemoglobin saturation being fixed at 50%
C. Cooperative binding of oxygen molecules to hemoglobin
D. Linear increase in oxygen-binding with rising pO2
C. Cooperative binding of oxygen molecules to hemoglobin
Rationale: The sigmoidal shape results from cooperative binding. When one
oxygen molecule binds to hemoglobin, it increases the affinity for subsequent
oxygen molecules.
In which part of the oxygen-hemoglobin dissociation curve does hemoglobin have
the highest oxygen saturation?
A. Left side (low pO2)
B. Flat portion at the right (high pO2)
C. Steep portion (moderate pO2)
D. Middle portion of the curve
B. Flat portion at the right (high pO2)
,Rationale: The flat portion of the curve represents high pO2 conditions, such as in
the lungs, where hemoglobin is almost fully saturated with oxygen (~100%
saturation).
What is the clinical significance of the steep portion of the oxygen-hemoglobin
dissociation curve?
A. Minimal oxygen release at tissues
B. Enhanced oxygen uptake in the lungs
C. Large oxygen release with small pO2 changes
D. No oxygen release despite low pO2
C. Large oxygen release with small pO2 changes
Rationale: The steep portion allows for significant oxygen release from
hemoglobin in response to small drops in pO2, facilitating oxygen delivery to
actively metabolizing tissues.
Which factor causes a rightward shift in the oxygen-hemoglobin dissociation
curve?
A. Decreased temperature
B. Increased pH
C. Increased 2,3-BPG
D. Hypocapnia
C. Increased 2,3-BPG
,Rationale: Increased 2,3-BPG production lowers hemoglobin's affinity for
oxygen, shifting the curve to the right and promoting oxygen unloading to
tissues.
What happens during a leftward shift of the oxygen-hemoglobin dissociation
curve?
A. Easier oxygen release at tissues
B. Increased hemoglobin affinity for oxygen
C. Higher CO2 levels
D. Acidosis
B. Increased hemoglobin affinity for oxygen
Rationale: A leftward shift means that hemoglobin binds oxygen more tightly,
reducing oxygen release to tissues but enhancing oxygen loading in the lungs.
Which of the following conditions is likely to cause a leftward shift of the curve?
A. Fever
B. Alkalosis
C. Hypercapnia
D. Increased 2,3-BPG
B. Alkalosis
, Rationale: Alkalosis (higher pH) increases hemoglobin's affinity for oxygen,
causing a leftward shift in the oxygen-hemoglobin dissociation curve.
What is the role of 2,3-Bisphosphoglycerate (2,3-BPG) in oxygen transport?
A. Enhances oxygen loading in the lungs
B. Stabilizes deoxygenated hemoglobin, promoting oxygen release
C. Shifts the curve to the left
D. Reduces oxygen delivery to tissues
B. Stabilizes deoxygenated hemoglobin, promoting oxygen release
Rationale: 2,3-BPG binds to deoxygenated hemoglobin, reducing its oxygen
affinity and facilitating oxygen release at the tissue level, causing a rightward
shift.
How does carbon monoxide (CO) poisoning affect the oxygen-hemoglobin
dissociation curve?
A. Shifts the curve to the right
B. No effect on the curve
C. Shifts the curve to the left, inhibiting oxygen release
D. Increases hemoglobin saturation
C. Shifts the curve to the left, inhibiting oxygen release
Rationale: CO binds with high affinity to hemoglobin, preventing oxygen binding
and shifting the curve to the left, which reduces oxygen release to tissues.
