BIOS255 — Anatomy & Physiology III Exam 2 Review (2026–2027)
Exam 2: BIOS 255 / BIOS255 (2026/2027 Update)
Anatomy and Physiology III Review
Questions and Verified Answers | 100% Correct | Grade A
Chamberlain University • 120 Comprehensive Questions • Cognitive Mix: 25% Recall / 50% Application / 25%
Analysis
Section 1: Blood and Hematology
Q1–Q25 • Blood Composition, Hematopoiesis, RBCs, WBCs, Platelets,
Hemostasis, Blood Typing, & Blood Disorders
Q1: A laboratory technician centrifuges a tube of whole blood collected in an anticoagulant. After 10
minutes at high speed, three distinct layers are visible. Which of the following best describes the relative
proportions of these layers in a healthy adult?
A. Plasma ~55%, buffy coat ~1%, erythrocytes ~44% [CORRECT]
B. Plasma ~45%, buffy coat ~5%, erythrocytes ~50%
C. Plasma ~55%, buffy coat ~5%, erythrocytes ~40%
D. Plasma ~45%, buffy coat ~1%, erythrocytes ~54%
Correct Answer: A — Plasma ~55%, buffy coat ~1%, erythrocytes ~44%
Rationale: Centrifugation separates whole blood into three layers by density: plasma (the lightest,
straw-colored fluid) constitutes approximately 55% of the total volume; the buffy coat (leukocytes and platelets)
forms a thin pale layer representing less than 1% of total volume; and the packed erythrocyte layer at the
bottom accounts for roughly 44% (the hematocrit). Option B reverses the plasma/erythrocyte ratio and
overstates the buffy coat. Option C overstates the buffy coat. Option D inverts the plasma-to-erythrocyte ratio,
which would suggest polycythemia.
Q2: A biochemistry panel reveals that a patient's plasma contains approximately 92% water, 7%
proteins, and 1% other solutes. Which plasma protein is the MOST abundant and is primarily
responsible for maintaining plasma colloid osmotic pressure?
A. Fibrinogen
B. Albumin [CORRECT]
C. Globulins (alpha, beta, gamma)
D. Prothrombin
Correct Answer: B — Albumin
Rationale: Albumin is the most abundant plasma protein (approximately 60% of total plasma protein) and is the
principal determinant of plasma colloid osmotic pressure, holding fluid within the vascular compartment.
Fibrinogen, while essential for clotting, constitutes only about 4% of plasma protein. Globulins (alpha, beta,
and gamma) handle transport and immunity but contribute less to osmotic pressure. Prothrombin is a clotting
factor present in trace amounts and does not contribute significantly to oncotic pressure.
Chamberlain University • Verified Answers • Grade A Page 1
,BIOS255 — Anatomy & Physiology III Exam 2 Review (2026–2027)
Q3: A peripheral blood smear is examined under microscopy. The technologist identifies anucleate,
biconcave cells approximately 7–8 µm in diameter. Which structural feature most directly enables these
cells to perform their primary function of gas transport?
A. Presence of a multilobed nucleus allowing flexibility
B. Abundant rough endoplasmic reticulum for protein synthesis
C. Biconcave shape with a network of spectrin proteins increasing surface area [CORRECT]
D. Numerous mitochondria generating ATP for active transport of oxygen
Correct Answer: C — Biconcave shape with a network of spectrin proteins increasing surface area
Rationale: Mature erythrocytes are anucleate and lack organelles, including mitochondria, allowing maximal
packing of hemoglobin. The biconcave disc shape, maintained by a spectrin–actin cytoskeletal network,
increases surface area for gas diffusion and permits deformation through narrow capillaries. Option A is wrong
because mature RBCs lack nuclei. Option B is incorrect because RBCs lack ribosomes and ER. Option D is
incorrect because RBCs rely on anaerobic glycolysis, not mitochondrial oxidative phosphorylation, to preserve
oxygen for delivery to tissues.
Q4: A 6-year-old child presents with persistent anemia. Bone marrow biopsy confirms reduced
hematopoietic activity. In a healthy adult, which anatomical site is the PRIMARY location of
hematopoiesis?
A. Liver (hepatic sinusoids)
B. Spleen (red pulp)
C. Yellow bone marrow of long bones
D. Red bone marrow of axial skeleton and proximal epiphyses [CORRECT]
Correct Answer: D — Red bone marrow of axial skeleton and proximal epiphyses
Rationale: In adults, hematopoiesis occurs primarily in the red bone marrow of the axial skeleton (sternum,
vertebrae, ribs, pelvis, skull) and the proximal epiphyses of the humerus and femur. The liver and spleen are
major hematopoietic sites in the fetus but serve only as extramedullary (compensatory) sites in adults under
pathological stress. Yellow bone marrow is adipose-rich and inactive, though it can revert to red marrow in
severe hematologic disease. Recognizing the adult site guides biopsy location (e.g., posterior iliac crest).
Q5: A researcher isolates a population of cells from bone marrow that can self-renew and give rise to all
blood cell lineages. Which surface marker best characterizes these pluripotent hematopoietic stem cells
(HSCs)?
A. CD34 [CORRECT]
B. CD38
C. CD8
D. CD19
Correct Answer: A — CD34
Rationale: Pluripotent hematopoietic stem cells are characterized by the surface marker CD34 positive and
CD38 negative (CD34+/CD38−). CD34 is heavily used clinically to identify and isolate HSCs for bone marrow
transplantation. CD38 is a marker of differentiation, so its presence indicates lineage commitment. CD8
identifies cytotoxic T lymphocytes, and CD19 identifies B lymphocytes, both of which are downstream
differentiated progeny, not pluripotent stem cells.
Chamberlain University • Verified Answers • Grade A Page 2
,BIOS255 — Anatomy & Physiology III Exam 2 Review (2026–2027)
Q6: A patient with chronic kidney disease presents with a hemoglobin of 8.2 g/dL and complaints of
fatigue. Which mechanism best explains the pathogenesis of this patient's anemia?
A. Decreased erythropoietin production by the renal peritubular interstitial fibroblasts [CORRECT]
B. Increased hepcidin release from the liver suppressing iron absorption
C. Direct destruction of red bone marrow by circulating urea
D. Loss of intrinsic factor leading to impaired vitamin B12 absorption
Correct Answer: A — Decreased erythropoietin production by the renal peritubular interstitial
fibroblasts
Rationale: The kidneys, specifically the peritubular interstitial fibroblasts of the renal cortex, are the primary
source of erythropoietin (EPO) in adults. EPO stimulates red bone marrow to increase erythropoiesis. In
chronic kidney disease, EPO production falls, causing normocytic normochromic anemia. Option B (hepcidin)
occurs in anemia of chronic disease but is not the primary mechanism in CKD. Option C is incorrect because
uremia does not directly destroy bone marrow. Option D describes pernicious anemia, a separate etiology
involving gastric parietal cells.
Q7: During erythropoiesis, which developmental stage is the FIRST to lose its nucleus, marking the
transition from a nucleated precursor to a reticulocyte?
A. Proerythroblast
B. Basophilic erythroblast
C. Normoblast (orthochromatic erythroblast) [CORRECT]
D. Reticulocyte
Correct Answer: C — Normoblast (orthochromatic erythroblast)
Rationale: During erythropoiesis, the orthochromatic erythroblast (normoblast) is the last nucleated stage. Its
nucleus is then extruded, producing a reticulocyte, which still contains residual ribosomal RNA and can
synthesize hemoglobin for ~1–2 days before maturing into a fully functional erythrocyte. The proerythroblast is
the earliest committed precursor and still has a large nucleus. The basophilic erythroblast has a darker nucleus
due to intense RNA production but still retains its nucleus. The reticulocyte is by definition already anucleate.
Q8: A physiology student asks why healthy adults must produce approximately 2.5 million erythrocytes
per second. What is the approximate lifespan of a circulating erythrocyte, and where are senescent RBCs
primarily destroyed?
A. 60 days; destroyed primarily in the liver
B. 120 days; destroyed primarily by splenic macrophages [CORRECT]
C. 90 days; destroyed primarily in the bone marrow
D. 150 days; destroyed primarily by pulmonary macrophages
Correct Answer: B — 120 days; destroyed primarily by splenic macrophages
Rationale: Mature erythrocytes circulate for approximately 120 days. As they age, their membranes lose
flexibility and surface antigens change, making them recognizable to macrophages, primarily in the red pulp of
the spleen (and to a lesser extent the liver). The spleen is therefore called the 'graveyard of RBCs.' The liver
plays a secondary role. Bone marrow and lungs are not significant sites of normal RBC destruction. The
120-day lifespan, combined with ~25 trillion RBCs in circulation, accounts for the high production rate.
Chamberlain University • Verified Answers • Grade A Page 3
, BIOS255 — Anatomy & Physiology III Exam 2 Review (2026–2027)
Q9: A 25-year-old African American man presents with episodic painful crises. Hemoglobin
electrophoresis reveals a single amino acid substitution of glutamic acid to valine in the β-globin chain.
Which adult hemoglobin variant is most consistent with this finding?
A. Hemoglobin A (α2β2)
B. Hemoglobin A2 (α2δ2)
C. Hemoglobin F (α2γ2)
D. Hemoglobin S (α2βS2) [CORRECT]
Correct Answer: D — Hemoglobin S (α2βS2)
Rationale: Hemoglobin S results from a single point mutation in the β-globin gene (HBB) substituting valine for
glutamic acid at position 6. Under low oxygen tension, HbS polymerizes, causing erythrocytes to sickle, leading
to vaso-occlusive crises, hemolysis, and end-organ damage. Hemoglobin A (α2β2) is the normal adult form
(>95%). Hemoglobin A2 (α2δ2) is a minor normal adult variant (<3.5%, elevated in β-thalassemia).
Hemoglobin F (α2γ2) is the dominant hemoglobin during fetal life and is normally suppressed after birth.
Q10: A 45-year-old woman presents with fatigue, pallor, and pica (craving for ice). Laboratory findings:
hemoglobin 9.0 g/dL, MCV 72 fL, serum ferritin 8 ng/mL (low), TIBC elevated. Which is the most likely
diagnosis, and what is the underlying pathophysiologic mechanism?
A. Vitamin B12 deficiency anemia due to impaired DNA synthesis
B. Iron deficiency anemia due to inadequate heme synthesis [CORRECT]
C. Anemia of chronic disease due to hepcidin-mediated iron sequestration
D. Hemolytic anemia due to premature RBC destruction
Correct Answer: B — Iron deficiency anemia due to inadequate heme synthesis
Rationale: Low MCV (microcytic), low serum ferritin, and elevated TIBC are classic for iron deficiency
anemia. Iron is the central atom of heme; when iron is deficient, heme synthesis is impaired, resulting in smaller
(microcytic) and pale (hypochromic) erythrocytes. Option A (B12 deficiency) causes macrocytic (high MCV)
anemia due to impaired DNA synthesis. Option C (anemia of chronic disease) typically shows low TIBC and
normal/high ferritin. Option D (hemolytic anemia) typically presents with normocytic anemia, elevated
reticulocyte count, and increased LDH/unconjugated bilirubin.
Q11: A complete blood count with differential returns the following percentages: neutrophils 60%,
lymphocytes 30%, monocytes 6%, eosinophils 3%, basophils 1%. Which leukocyte is normally the
MOST abundant in peripheral blood of an adult?
A. Lymphocyte
B. Eosinophil
C. Neutrophil [CORRECT]
D. Monocyte
Correct Answer: C — Neutrophil
Rationale: Neutrophils are the most abundant circulating leukocyte in adults, comprising approximately
60–70% of total WBCs. They are first responders to bacterial infection and acute inflammation. Lymphocytes
(20–25%) are the second most abundant, dominant in children. Monocytes (3–8%) circulate briefly before
becoming tissue macrophages. Eosinophils (2–4%) respond to parasitic infections and allergic reactions.
Basophils (0.5–1%) are the least abundant granulocyte and mediate type I hypersensitivity.
Chamberlain University • Verified Answers • Grade A Page 4
Exam 2: BIOS 255 / BIOS255 (2026/2027 Update)
Anatomy and Physiology III Review
Questions and Verified Answers | 100% Correct | Grade A
Chamberlain University • 120 Comprehensive Questions • Cognitive Mix: 25% Recall / 50% Application / 25%
Analysis
Section 1: Blood and Hematology
Q1–Q25 • Blood Composition, Hematopoiesis, RBCs, WBCs, Platelets,
Hemostasis, Blood Typing, & Blood Disorders
Q1: A laboratory technician centrifuges a tube of whole blood collected in an anticoagulant. After 10
minutes at high speed, three distinct layers are visible. Which of the following best describes the relative
proportions of these layers in a healthy adult?
A. Plasma ~55%, buffy coat ~1%, erythrocytes ~44% [CORRECT]
B. Plasma ~45%, buffy coat ~5%, erythrocytes ~50%
C. Plasma ~55%, buffy coat ~5%, erythrocytes ~40%
D. Plasma ~45%, buffy coat ~1%, erythrocytes ~54%
Correct Answer: A — Plasma ~55%, buffy coat ~1%, erythrocytes ~44%
Rationale: Centrifugation separates whole blood into three layers by density: plasma (the lightest,
straw-colored fluid) constitutes approximately 55% of the total volume; the buffy coat (leukocytes and platelets)
forms a thin pale layer representing less than 1% of total volume; and the packed erythrocyte layer at the
bottom accounts for roughly 44% (the hematocrit). Option B reverses the plasma/erythrocyte ratio and
overstates the buffy coat. Option C overstates the buffy coat. Option D inverts the plasma-to-erythrocyte ratio,
which would suggest polycythemia.
Q2: A biochemistry panel reveals that a patient's plasma contains approximately 92% water, 7%
proteins, and 1% other solutes. Which plasma protein is the MOST abundant and is primarily
responsible for maintaining plasma colloid osmotic pressure?
A. Fibrinogen
B. Albumin [CORRECT]
C. Globulins (alpha, beta, gamma)
D. Prothrombin
Correct Answer: B — Albumin
Rationale: Albumin is the most abundant plasma protein (approximately 60% of total plasma protein) and is the
principal determinant of plasma colloid osmotic pressure, holding fluid within the vascular compartment.
Fibrinogen, while essential for clotting, constitutes only about 4% of plasma protein. Globulins (alpha, beta,
and gamma) handle transport and immunity but contribute less to osmotic pressure. Prothrombin is a clotting
factor present in trace amounts and does not contribute significantly to oncotic pressure.
Chamberlain University • Verified Answers • Grade A Page 1
,BIOS255 — Anatomy & Physiology III Exam 2 Review (2026–2027)
Q3: A peripheral blood smear is examined under microscopy. The technologist identifies anucleate,
biconcave cells approximately 7–8 µm in diameter. Which structural feature most directly enables these
cells to perform their primary function of gas transport?
A. Presence of a multilobed nucleus allowing flexibility
B. Abundant rough endoplasmic reticulum for protein synthesis
C. Biconcave shape with a network of spectrin proteins increasing surface area [CORRECT]
D. Numerous mitochondria generating ATP for active transport of oxygen
Correct Answer: C — Biconcave shape with a network of spectrin proteins increasing surface area
Rationale: Mature erythrocytes are anucleate and lack organelles, including mitochondria, allowing maximal
packing of hemoglobin. The biconcave disc shape, maintained by a spectrin–actin cytoskeletal network,
increases surface area for gas diffusion and permits deformation through narrow capillaries. Option A is wrong
because mature RBCs lack nuclei. Option B is incorrect because RBCs lack ribosomes and ER. Option D is
incorrect because RBCs rely on anaerobic glycolysis, not mitochondrial oxidative phosphorylation, to preserve
oxygen for delivery to tissues.
Q4: A 6-year-old child presents with persistent anemia. Bone marrow biopsy confirms reduced
hematopoietic activity. In a healthy adult, which anatomical site is the PRIMARY location of
hematopoiesis?
A. Liver (hepatic sinusoids)
B. Spleen (red pulp)
C. Yellow bone marrow of long bones
D. Red bone marrow of axial skeleton and proximal epiphyses [CORRECT]
Correct Answer: D — Red bone marrow of axial skeleton and proximal epiphyses
Rationale: In adults, hematopoiesis occurs primarily in the red bone marrow of the axial skeleton (sternum,
vertebrae, ribs, pelvis, skull) and the proximal epiphyses of the humerus and femur. The liver and spleen are
major hematopoietic sites in the fetus but serve only as extramedullary (compensatory) sites in adults under
pathological stress. Yellow bone marrow is adipose-rich and inactive, though it can revert to red marrow in
severe hematologic disease. Recognizing the adult site guides biopsy location (e.g., posterior iliac crest).
Q5: A researcher isolates a population of cells from bone marrow that can self-renew and give rise to all
blood cell lineages. Which surface marker best characterizes these pluripotent hematopoietic stem cells
(HSCs)?
A. CD34 [CORRECT]
B. CD38
C. CD8
D. CD19
Correct Answer: A — CD34
Rationale: Pluripotent hematopoietic stem cells are characterized by the surface marker CD34 positive and
CD38 negative (CD34+/CD38−). CD34 is heavily used clinically to identify and isolate HSCs for bone marrow
transplantation. CD38 is a marker of differentiation, so its presence indicates lineage commitment. CD8
identifies cytotoxic T lymphocytes, and CD19 identifies B lymphocytes, both of which are downstream
differentiated progeny, not pluripotent stem cells.
Chamberlain University • Verified Answers • Grade A Page 2
,BIOS255 — Anatomy & Physiology III Exam 2 Review (2026–2027)
Q6: A patient with chronic kidney disease presents with a hemoglobin of 8.2 g/dL and complaints of
fatigue. Which mechanism best explains the pathogenesis of this patient's anemia?
A. Decreased erythropoietin production by the renal peritubular interstitial fibroblasts [CORRECT]
B. Increased hepcidin release from the liver suppressing iron absorption
C. Direct destruction of red bone marrow by circulating urea
D. Loss of intrinsic factor leading to impaired vitamin B12 absorption
Correct Answer: A — Decreased erythropoietin production by the renal peritubular interstitial
fibroblasts
Rationale: The kidneys, specifically the peritubular interstitial fibroblasts of the renal cortex, are the primary
source of erythropoietin (EPO) in adults. EPO stimulates red bone marrow to increase erythropoiesis. In
chronic kidney disease, EPO production falls, causing normocytic normochromic anemia. Option B (hepcidin)
occurs in anemia of chronic disease but is not the primary mechanism in CKD. Option C is incorrect because
uremia does not directly destroy bone marrow. Option D describes pernicious anemia, a separate etiology
involving gastric parietal cells.
Q7: During erythropoiesis, which developmental stage is the FIRST to lose its nucleus, marking the
transition from a nucleated precursor to a reticulocyte?
A. Proerythroblast
B. Basophilic erythroblast
C. Normoblast (orthochromatic erythroblast) [CORRECT]
D. Reticulocyte
Correct Answer: C — Normoblast (orthochromatic erythroblast)
Rationale: During erythropoiesis, the orthochromatic erythroblast (normoblast) is the last nucleated stage. Its
nucleus is then extruded, producing a reticulocyte, which still contains residual ribosomal RNA and can
synthesize hemoglobin for ~1–2 days before maturing into a fully functional erythrocyte. The proerythroblast is
the earliest committed precursor and still has a large nucleus. The basophilic erythroblast has a darker nucleus
due to intense RNA production but still retains its nucleus. The reticulocyte is by definition already anucleate.
Q8: A physiology student asks why healthy adults must produce approximately 2.5 million erythrocytes
per second. What is the approximate lifespan of a circulating erythrocyte, and where are senescent RBCs
primarily destroyed?
A. 60 days; destroyed primarily in the liver
B. 120 days; destroyed primarily by splenic macrophages [CORRECT]
C. 90 days; destroyed primarily in the bone marrow
D. 150 days; destroyed primarily by pulmonary macrophages
Correct Answer: B — 120 days; destroyed primarily by splenic macrophages
Rationale: Mature erythrocytes circulate for approximately 120 days. As they age, their membranes lose
flexibility and surface antigens change, making them recognizable to macrophages, primarily in the red pulp of
the spleen (and to a lesser extent the liver). The spleen is therefore called the 'graveyard of RBCs.' The liver
plays a secondary role. Bone marrow and lungs are not significant sites of normal RBC destruction. The
120-day lifespan, combined with ~25 trillion RBCs in circulation, accounts for the high production rate.
Chamberlain University • Verified Answers • Grade A Page 3
, BIOS255 — Anatomy & Physiology III Exam 2 Review (2026–2027)
Q9: A 25-year-old African American man presents with episodic painful crises. Hemoglobin
electrophoresis reveals a single amino acid substitution of glutamic acid to valine in the β-globin chain.
Which adult hemoglobin variant is most consistent with this finding?
A. Hemoglobin A (α2β2)
B. Hemoglobin A2 (α2δ2)
C. Hemoglobin F (α2γ2)
D. Hemoglobin S (α2βS2) [CORRECT]
Correct Answer: D — Hemoglobin S (α2βS2)
Rationale: Hemoglobin S results from a single point mutation in the β-globin gene (HBB) substituting valine for
glutamic acid at position 6. Under low oxygen tension, HbS polymerizes, causing erythrocytes to sickle, leading
to vaso-occlusive crises, hemolysis, and end-organ damage. Hemoglobin A (α2β2) is the normal adult form
(>95%). Hemoglobin A2 (α2δ2) is a minor normal adult variant (<3.5%, elevated in β-thalassemia).
Hemoglobin F (α2γ2) is the dominant hemoglobin during fetal life and is normally suppressed after birth.
Q10: A 45-year-old woman presents with fatigue, pallor, and pica (craving for ice). Laboratory findings:
hemoglobin 9.0 g/dL, MCV 72 fL, serum ferritin 8 ng/mL (low), TIBC elevated. Which is the most likely
diagnosis, and what is the underlying pathophysiologic mechanism?
A. Vitamin B12 deficiency anemia due to impaired DNA synthesis
B. Iron deficiency anemia due to inadequate heme synthesis [CORRECT]
C. Anemia of chronic disease due to hepcidin-mediated iron sequestration
D. Hemolytic anemia due to premature RBC destruction
Correct Answer: B — Iron deficiency anemia due to inadequate heme synthesis
Rationale: Low MCV (microcytic), low serum ferritin, and elevated TIBC are classic for iron deficiency
anemia. Iron is the central atom of heme; when iron is deficient, heme synthesis is impaired, resulting in smaller
(microcytic) and pale (hypochromic) erythrocytes. Option A (B12 deficiency) causes macrocytic (high MCV)
anemia due to impaired DNA synthesis. Option C (anemia of chronic disease) typically shows low TIBC and
normal/high ferritin. Option D (hemolytic anemia) typically presents with normocytic anemia, elevated
reticulocyte count, and increased LDH/unconjugated bilirubin.
Q11: A complete blood count with differential returns the following percentages: neutrophils 60%,
lymphocytes 30%, monocytes 6%, eosinophils 3%, basophils 1%. Which leukocyte is normally the
MOST abundant in peripheral blood of an adult?
A. Lymphocyte
B. Eosinophil
C. Neutrophil [CORRECT]
D. Monocyte
Correct Answer: C — Neutrophil
Rationale: Neutrophils are the most abundant circulating leukocyte in adults, comprising approximately
60–70% of total WBCs. They are first responders to bacterial infection and acute inflammation. Lymphocytes
(20–25%) are the second most abundant, dominant in children. Monocytes (3–8%) circulate briefly before
becoming tissue macrophages. Eosinophils (2–4%) respond to parasitic infections and allergic reactions.
Basophils (0.5–1%) are the least abundant granulocyte and mediate type I hypersensitivity.
Chamberlain University • Verified Answers • Grade A Page 4
