BIO 201 Exam 3 - Anatomy & Physiology I - StraighterLine 2026/2027 Page 1
BIO 201 Exam 3 — Anatomy & Physiology I
StraighterLine 2026/2027 Edition — 100 Actual Questions & Answers with Comprehensive Rationales
Comprehensive coverage: Blood Composition • Blood Typing • Heart Anatomy • Blood Vessels • Hemodynamics •
Lymphatic System and Immunity
Section 1: Blood Composition and Functions
Plasma, Formed Elements, Hemopoiesis, and Hemostasis
Question Range: Q1 - Q16
Q1. A 25-year-old female presents with fatigue and pallor. Lab results show hemoglobin of 9.2 g/dL (normal
12-15) and a hematocrit of 27% (normal 37-48%). Which plasma protein is primarily responsible for
maintaining blood colloid osmotic pressure and preventing edema in this patient despite her low hematocrit?
A. Fibrinogen, because it is the largest plasma protein and provides bulk osmotic pull
B. Albumin, because it is the most abundant plasma protein and provides approximately 75% of colloid osmotic
pressure [CORRECT]
C. Globulins, because they transport hormones and provide immune function
D. Hemoglobin, because it is the oxygen-carrying pigment released by RBCs
Correct Answer: B
Rationale: Albumin is the most abundant plasma protein (3.5-5.0 g/dL) and is the dominant contributor to blood colloid
osmotic pressure (COP), generating roughly 75% of the total COP that holds fluid within the vascular compartment. Fibrinogen
is consumed in clotting and contributes little to COP; globulins (alpha, beta, gamma) mainly transport and provide immunity;
hemoglobin is normally intracellular in RBCs, not free in plasma.
Q2. A clinical laboratory technician is examining a peripheral blood smear under the microscope. Which of the
following descriptions correctly identifies a mature erythrocyte and the anatomical feature that allows it to
perform its primary physiological function?
A. A nucleated cell with a flattened spherical shape and abundant mitochondria for aerobic metabolism
B. An anucleate biconcave disc whose unique shape increases surface area to volume ratio for optimal gas
diffusion [CORRECT]
C. A cell packed with ribosomes and a large Golgi apparatus to synthesize hemoglobin de novo
D. A spherical phagocytic cell containing azurophilic granules and a multilobed nucleus
Correct Answer: B
Rationale: Mature erythrocytes in circulating blood are anucleate, biconcave discs approximately 7.5 micrometers in diameter.
Their biconcave shape increases the surface-area-to-volume ratio, shortening the diffusion distance for O2 and CO2 and
allowing gas exchange approximately 1.5 times faster than a flat disc of equal volume. They expel their nucleus (and
ribosomes/organelles) during terminal differentiation, replacing cytoplasm with roughly 280 million hemoglobin molecules.
Comprehensive 100-Question Exam with Rationales 100% Guarantee Pass Edition
,BIO 201 Exam 3 - Anatomy & Physiology I - StraighterLine 2026/2027 Page 2
Q3. A 6-year-old boy is brought to the clinic with recurrent bacterial infections. Complete blood count reveals
an absolute neutrophil count of 0.4 x 10^9/L (severely low). Which of the following correctly describes the
lineage, primary function, and typical lifespan of the granulocyte that is deficient in this patient?
A. Lymphoid lineage; antibody production; lifespan of years in circulation
B. Myeloid lineage; phagocytosis of pyogenic bacteria; lifespan of hours to a few days in tissues [CORRECT]
C. Myeloid lineage; release of histamine during allergic responses; lifespan of weeks
D. Lymphoid lineage; cell-mediated cytotoxicity via perforin; lifespan of months
Correct Answer: B
Rationale: Neutrophils arise from the myeloid lineage under the influence of G-CSF. They are the first responders in acute
bacterial infection, performing phagocytosis and intracellular killing via myeloperoxidase, NADPH oxidase (respiratory burst),
and defensin granules. They are short-lived (6 hours to a few days in tissues), and the body must produce roughly 1.6 x 10^11
daily. Lymphocytes (lymphoid lineage) provide adaptive immunity, while basophils release histamine.
Q4. Hematopoiesis in a healthy adult primarily occurs in which anatomical location, and at what developmental
stage does this site become the dominant hematopoietic organ after fetal life?
A. Liver (hepatic phase) is the dominant site in adults; it begins producing blood cells at month 4 of gestation and
continues lifelong
B. Red bone marrow of the axial skeleton and proximal long bones is the dominant adult site; it becomes
predominant by the end of the 5th month of fetal development [CORRECT]
C. Yellow bone marrow of the appendicular skeleton; it begins hematopoiesis at birth and dominates lifelong
D. Spleen (splenic phase) is the primary adult site; it takes over hematopoiesis after birth
Correct Answer: B
Rationale: Hematopoiesis occurs in successive fetal sites: yolk sac (weeks 3 of gestation), liver and spleen (months 2-7, the
hepatic phase), and finally red bone marrow, which becomes the dominant hematopoietic site by the end of the 5th month of
fetal development and remains so throughout adulthood. In adults, red marrow is found in the axial skeleton (sternum, vertebrae,
ribs, skull, pelvis) and proximal epiphyses of the femur and humerus. Yellow marrow can revert to red under hematopoietic
stress.
Q5. A patient with chronic kidney disease has a hematocrit of 22%. Which hormone, released from which
organ, is deficient in this patient and is responsible for stimulating red blood cell production at the level of the
bone marrow CFU-E progenitor?
A. Thrombopoietin released from the liver; acts on megakaryocyte-colony forming units
B. Erythropoietin (EPO) released from the renal peritubular interstitial fibroblasts; acts on CFU-E progenitors
to promote proliferation and survival of erythroid precursors [CORRECT]
C. Erythropoietin released from the liver; acts on mature erythrocytes in the circulation
D. Granulocyte colony-stimulating factor released from the bone marrow stroma; acts on neutrophil precursors
Correct Answer: B
Rationale: Erythropoietin (EPO) is a glycoprotein hormone synthesized primarily by peritubular interstitial fibroblasts of the
renal cortex. It is released in response to tissue hypoxia (sensed via HIF-2 alpha). EPO binds receptors on CFU-E
(colony-forming unit-erythroid) progenitors, preventing apoptosis and promoting proliferation and differentiation into
proerythroblasts. The liver produces small amounts of EPO (especially during fetal life); thrombopoietin (TPO) is hepatic and
targets megakaryocytes.
Comprehensive 100-Question Exam with Rationales 100% Guarantee Pass Edition
,BIO 201 Exam 3 - Anatomy & Physiology I - StraighterLine 2026/2027 Page 3
Q6. A patient presents with prolonged bleeding after a minor dental procedure. Lab testing shows normal
platelet count, normal PT, but elevated aPTT. Which cell fragment, derived from the listed lineage, is
responsible for the primary hemostatic plug formation, and what substance do they release to promote local
vasoconstriction?
A. Erythrocytes release nitric oxide; they are derived from the myeloid lineage CFU-GEMM
B. Platelets (thrombocytes) release thromboxane A2 (TXA2) and serotonin; they are cytoplasmic fragments of
megakaryocytes derived from the myeloid lineage [CORRECT]
C. Platelets release bradykinin and histamine; they are derived from lymphoid lineage CFU-L
D. Megakaryocytes release prostacyclin (PGI2); they are multinucleated cells of the erythroid lineage
Correct Answer: B
Rationale: Platelets are anucleate cytoplasmic fragments shed from megakaryocytes (myeloid lineage, CFU-GEMM ->
CFU-Meg -> megakaryocyte). On activation at a vascular injury site, platelets degranulate and release thromboxane A2
(TXA2), serotonin, and ADP. TXA2 is a potent local vasoconstrictor and platelet agonist that amplifies the platelet plug.
Prostacyclin (PGI2) is produced by intact endothelial cells and antagonizes platelet aggregation. The aPTT abnormality suggests
an intrinsic pathway factor deficiency, not a primary platelet count defect.
Q7. A patient is on warfarin therapy. Which of the following correctly describes the vitamin-K-dependent
coagulation factors that are inhibited, and the pathway in which they participate?
A. Factors II, VII, IX, and X (and Proteins C and S) require vitamin K for gamma-carboxylation; warfarin
inhibits this post-translational modification and predominantly affects the extrinsic and common pathways
[CORRECT]
B. Factors I, V, VIII, and XIII require vitamin K for activation; warfarin inhibits only the intrinsic pathway
C. Only factor VII requires vitamin K; warfarin inhibits platelet aggregation via COX-1 inhibition
D. Factors II, VII, IX, and X require vitamin C for hydroxylation; warfarin mimics scurvy pathology
Correct Answer: A
Rationale: Vitamin K is a cofactor for gamma-glutamyl carboxylase, which adds a second carboxyl group to specific glutamate
residues on factors II (prothrombin), VII, IX, and X, as well as the natural anticoagulants Protein C and Protein S. This
gamma-carboxylation allows calcium binding, which is required for the factors to anchor onto activated platelet phospholipid
surfaces. Warfarin inhibits vitamin K epoxide reductase (VKORC1), preventing recycling of vitamin K to its active form.
PT/INR measures the extrinsic + common pathway (Factors VII, X, II, I).
Comprehensive 100-Question Exam with Rationales 100% Guarantee Pass Edition
, BIO 201 Exam 3 - Anatomy & Physiology I - StraighterLine 2026/2027 Page 4
Q8. Order the following events in the EXTRINSIC pathway of blood coagulation: (1) Factor VIIa activates
Factor X to Xa; (2) Tissue factor (TF, thromboplastin) is exposed by subendothelial cells; (3) Factor Xa
combines with Va, platelet phospholipid, and Ca2+ to form prothrombinase; (4) TF binds Factor VII and
activates it to VIIa.
A. 2, 4, 1, 3 [CORRECT]
B. 4, 2, 1, 3
C. 2, 1, 4, 3
D. 3, 1, 4, 2
Correct Answer: A
Rationale: The extrinsic pathway is initiated when vascular injury exposes subendothelial cells (smooth muscle cells,
fibroblasts) that express Tissue Factor (TF, thromboplastin, factor III) on their surfaces (event 2). TF then binds circulating
Factor VII and acts as a cofactor, converting it to active VIIa (event 4). The TF-VIIa-Ca2+ complex then activates Factor X to
Xa (event 1). Factor Xa, with cofactor Va, on the activated platelet phospholipid surface in the presence of Ca2+ forms the
prothrombinase complex (event 3), which then converts prothrombin (II) to thrombin (IIa). The extrinsic pathway is rapid (≈15
seconds) and assessed by PT/INR.
Q9. A 45-year-old man is brought to the ER with massive hematemesis. Labs reveal hemoglobin 4.8 g/dL,
platelets 8,000/microL, PT 35s, aPTT 78s, fibrinogen 75 mg/dL, and D-dimer markedly elevated. The
emergency physician diagnoses acute DIC. Which best explains the simultaneous prolongation of PT, aPTT,
and thrombocytopenia in DIC?
A. DIC is caused by isolated factor VIII deficiency; PT prolongation is incidental
B. DIC triggers widespread activation of coagulation that consumes platelets and clotting factors (II, V, VIII,
fibrinogen), producing global clotting failure; microvascular thrombi also deposit platelets [CORRECT]
C. DIC is caused by isolated thrombocytopenia; PT and aPTT prolongation is spurious
D. DIC is the result of vitamin K deficiency; aPTT prolongation is the only abnormality
Correct Answer: B
Rationale: Disseminated intravascular coagulation (DIC) is a disorder of widespread intravascular activation of coagulation
triggered by sepsis, trauma, malignancy, or obstetric catastrophe. Abundant tissue factor or cytokine-driven monocyte TF
expression triggers uncontrolled thrombin generation, consuming platelets, fibrinogen, Factors II, V, VIII, and protein C and S.
The consumption reduces clotting factor levels (prolonging PT and aPTT) and platelets (thrombocytopenia). Fibrin strands
deposit in the microvasculature, and secondary fibrinolysis elevates D-dimer.
Comprehensive 100-Question Exam with Rationales 100% Guarantee Pass Edition
BIO 201 Exam 3 — Anatomy & Physiology I
StraighterLine 2026/2027 Edition — 100 Actual Questions & Answers with Comprehensive Rationales
Comprehensive coverage: Blood Composition • Blood Typing • Heart Anatomy • Blood Vessels • Hemodynamics •
Lymphatic System and Immunity
Section 1: Blood Composition and Functions
Plasma, Formed Elements, Hemopoiesis, and Hemostasis
Question Range: Q1 - Q16
Q1. A 25-year-old female presents with fatigue and pallor. Lab results show hemoglobin of 9.2 g/dL (normal
12-15) and a hematocrit of 27% (normal 37-48%). Which plasma protein is primarily responsible for
maintaining blood colloid osmotic pressure and preventing edema in this patient despite her low hematocrit?
A. Fibrinogen, because it is the largest plasma protein and provides bulk osmotic pull
B. Albumin, because it is the most abundant plasma protein and provides approximately 75% of colloid osmotic
pressure [CORRECT]
C. Globulins, because they transport hormones and provide immune function
D. Hemoglobin, because it is the oxygen-carrying pigment released by RBCs
Correct Answer: B
Rationale: Albumin is the most abundant plasma protein (3.5-5.0 g/dL) and is the dominant contributor to blood colloid
osmotic pressure (COP), generating roughly 75% of the total COP that holds fluid within the vascular compartment. Fibrinogen
is consumed in clotting and contributes little to COP; globulins (alpha, beta, gamma) mainly transport and provide immunity;
hemoglobin is normally intracellular in RBCs, not free in plasma.
Q2. A clinical laboratory technician is examining a peripheral blood smear under the microscope. Which of the
following descriptions correctly identifies a mature erythrocyte and the anatomical feature that allows it to
perform its primary physiological function?
A. A nucleated cell with a flattened spherical shape and abundant mitochondria for aerobic metabolism
B. An anucleate biconcave disc whose unique shape increases surface area to volume ratio for optimal gas
diffusion [CORRECT]
C. A cell packed with ribosomes and a large Golgi apparatus to synthesize hemoglobin de novo
D. A spherical phagocytic cell containing azurophilic granules and a multilobed nucleus
Correct Answer: B
Rationale: Mature erythrocytes in circulating blood are anucleate, biconcave discs approximately 7.5 micrometers in diameter.
Their biconcave shape increases the surface-area-to-volume ratio, shortening the diffusion distance for O2 and CO2 and
allowing gas exchange approximately 1.5 times faster than a flat disc of equal volume. They expel their nucleus (and
ribosomes/organelles) during terminal differentiation, replacing cytoplasm with roughly 280 million hemoglobin molecules.
Comprehensive 100-Question Exam with Rationales 100% Guarantee Pass Edition
,BIO 201 Exam 3 - Anatomy & Physiology I - StraighterLine 2026/2027 Page 2
Q3. A 6-year-old boy is brought to the clinic with recurrent bacterial infections. Complete blood count reveals
an absolute neutrophil count of 0.4 x 10^9/L (severely low). Which of the following correctly describes the
lineage, primary function, and typical lifespan of the granulocyte that is deficient in this patient?
A. Lymphoid lineage; antibody production; lifespan of years in circulation
B. Myeloid lineage; phagocytosis of pyogenic bacteria; lifespan of hours to a few days in tissues [CORRECT]
C. Myeloid lineage; release of histamine during allergic responses; lifespan of weeks
D. Lymphoid lineage; cell-mediated cytotoxicity via perforin; lifespan of months
Correct Answer: B
Rationale: Neutrophils arise from the myeloid lineage under the influence of G-CSF. They are the first responders in acute
bacterial infection, performing phagocytosis and intracellular killing via myeloperoxidase, NADPH oxidase (respiratory burst),
and defensin granules. They are short-lived (6 hours to a few days in tissues), and the body must produce roughly 1.6 x 10^11
daily. Lymphocytes (lymphoid lineage) provide adaptive immunity, while basophils release histamine.
Q4. Hematopoiesis in a healthy adult primarily occurs in which anatomical location, and at what developmental
stage does this site become the dominant hematopoietic organ after fetal life?
A. Liver (hepatic phase) is the dominant site in adults; it begins producing blood cells at month 4 of gestation and
continues lifelong
B. Red bone marrow of the axial skeleton and proximal long bones is the dominant adult site; it becomes
predominant by the end of the 5th month of fetal development [CORRECT]
C. Yellow bone marrow of the appendicular skeleton; it begins hematopoiesis at birth and dominates lifelong
D. Spleen (splenic phase) is the primary adult site; it takes over hematopoiesis after birth
Correct Answer: B
Rationale: Hematopoiesis occurs in successive fetal sites: yolk sac (weeks 3 of gestation), liver and spleen (months 2-7, the
hepatic phase), and finally red bone marrow, which becomes the dominant hematopoietic site by the end of the 5th month of
fetal development and remains so throughout adulthood. In adults, red marrow is found in the axial skeleton (sternum, vertebrae,
ribs, skull, pelvis) and proximal epiphyses of the femur and humerus. Yellow marrow can revert to red under hematopoietic
stress.
Q5. A patient with chronic kidney disease has a hematocrit of 22%. Which hormone, released from which
organ, is deficient in this patient and is responsible for stimulating red blood cell production at the level of the
bone marrow CFU-E progenitor?
A. Thrombopoietin released from the liver; acts on megakaryocyte-colony forming units
B. Erythropoietin (EPO) released from the renal peritubular interstitial fibroblasts; acts on CFU-E progenitors
to promote proliferation and survival of erythroid precursors [CORRECT]
C. Erythropoietin released from the liver; acts on mature erythrocytes in the circulation
D. Granulocyte colony-stimulating factor released from the bone marrow stroma; acts on neutrophil precursors
Correct Answer: B
Rationale: Erythropoietin (EPO) is a glycoprotein hormone synthesized primarily by peritubular interstitial fibroblasts of the
renal cortex. It is released in response to tissue hypoxia (sensed via HIF-2 alpha). EPO binds receptors on CFU-E
(colony-forming unit-erythroid) progenitors, preventing apoptosis and promoting proliferation and differentiation into
proerythroblasts. The liver produces small amounts of EPO (especially during fetal life); thrombopoietin (TPO) is hepatic and
targets megakaryocytes.
Comprehensive 100-Question Exam with Rationales 100% Guarantee Pass Edition
,BIO 201 Exam 3 - Anatomy & Physiology I - StraighterLine 2026/2027 Page 3
Q6. A patient presents with prolonged bleeding after a minor dental procedure. Lab testing shows normal
platelet count, normal PT, but elevated aPTT. Which cell fragment, derived from the listed lineage, is
responsible for the primary hemostatic plug formation, and what substance do they release to promote local
vasoconstriction?
A. Erythrocytes release nitric oxide; they are derived from the myeloid lineage CFU-GEMM
B. Platelets (thrombocytes) release thromboxane A2 (TXA2) and serotonin; they are cytoplasmic fragments of
megakaryocytes derived from the myeloid lineage [CORRECT]
C. Platelets release bradykinin and histamine; they are derived from lymphoid lineage CFU-L
D. Megakaryocytes release prostacyclin (PGI2); they are multinucleated cells of the erythroid lineage
Correct Answer: B
Rationale: Platelets are anucleate cytoplasmic fragments shed from megakaryocytes (myeloid lineage, CFU-GEMM ->
CFU-Meg -> megakaryocyte). On activation at a vascular injury site, platelets degranulate and release thromboxane A2
(TXA2), serotonin, and ADP. TXA2 is a potent local vasoconstrictor and platelet agonist that amplifies the platelet plug.
Prostacyclin (PGI2) is produced by intact endothelial cells and antagonizes platelet aggregation. The aPTT abnormality suggests
an intrinsic pathway factor deficiency, not a primary platelet count defect.
Q7. A patient is on warfarin therapy. Which of the following correctly describes the vitamin-K-dependent
coagulation factors that are inhibited, and the pathway in which they participate?
A. Factors II, VII, IX, and X (and Proteins C and S) require vitamin K for gamma-carboxylation; warfarin
inhibits this post-translational modification and predominantly affects the extrinsic and common pathways
[CORRECT]
B. Factors I, V, VIII, and XIII require vitamin K for activation; warfarin inhibits only the intrinsic pathway
C. Only factor VII requires vitamin K; warfarin inhibits platelet aggregation via COX-1 inhibition
D. Factors II, VII, IX, and X require vitamin C for hydroxylation; warfarin mimics scurvy pathology
Correct Answer: A
Rationale: Vitamin K is a cofactor for gamma-glutamyl carboxylase, which adds a second carboxyl group to specific glutamate
residues on factors II (prothrombin), VII, IX, and X, as well as the natural anticoagulants Protein C and Protein S. This
gamma-carboxylation allows calcium binding, which is required for the factors to anchor onto activated platelet phospholipid
surfaces. Warfarin inhibits vitamin K epoxide reductase (VKORC1), preventing recycling of vitamin K to its active form.
PT/INR measures the extrinsic + common pathway (Factors VII, X, II, I).
Comprehensive 100-Question Exam with Rationales 100% Guarantee Pass Edition
, BIO 201 Exam 3 - Anatomy & Physiology I - StraighterLine 2026/2027 Page 4
Q8. Order the following events in the EXTRINSIC pathway of blood coagulation: (1) Factor VIIa activates
Factor X to Xa; (2) Tissue factor (TF, thromboplastin) is exposed by subendothelial cells; (3) Factor Xa
combines with Va, platelet phospholipid, and Ca2+ to form prothrombinase; (4) TF binds Factor VII and
activates it to VIIa.
A. 2, 4, 1, 3 [CORRECT]
B. 4, 2, 1, 3
C. 2, 1, 4, 3
D. 3, 1, 4, 2
Correct Answer: A
Rationale: The extrinsic pathway is initiated when vascular injury exposes subendothelial cells (smooth muscle cells,
fibroblasts) that express Tissue Factor (TF, thromboplastin, factor III) on their surfaces (event 2). TF then binds circulating
Factor VII and acts as a cofactor, converting it to active VIIa (event 4). The TF-VIIa-Ca2+ complex then activates Factor X to
Xa (event 1). Factor Xa, with cofactor Va, on the activated platelet phospholipid surface in the presence of Ca2+ forms the
prothrombinase complex (event 3), which then converts prothrombin (II) to thrombin (IIa). The extrinsic pathway is rapid (≈15
seconds) and assessed by PT/INR.
Q9. A 45-year-old man is brought to the ER with massive hematemesis. Labs reveal hemoglobin 4.8 g/dL,
platelets 8,000/microL, PT 35s, aPTT 78s, fibrinogen 75 mg/dL, and D-dimer markedly elevated. The
emergency physician diagnoses acute DIC. Which best explains the simultaneous prolongation of PT, aPTT,
and thrombocytopenia in DIC?
A. DIC is caused by isolated factor VIII deficiency; PT prolongation is incidental
B. DIC triggers widespread activation of coagulation that consumes platelets and clotting factors (II, V, VIII,
fibrinogen), producing global clotting failure; microvascular thrombi also deposit platelets [CORRECT]
C. DIC is caused by isolated thrombocytopenia; PT and aPTT prolongation is spurious
D. DIC is the result of vitamin K deficiency; aPTT prolongation is the only abnormality
Correct Answer: B
Rationale: Disseminated intravascular coagulation (DIC) is a disorder of widespread intravascular activation of coagulation
triggered by sepsis, trauma, malignancy, or obstetric catastrophe. Abundant tissue factor or cytokine-driven monocyte TF
expression triggers uncontrolled thrombin generation, consuming platelets, fibrinogen, Factors II, V, VIII, and protein C and S.
The consumption reduces clotting factor levels (prolonging PT and aPTT) and platelets (thrombocytopenia). Fibrin strands
deposit in the microvasculature, and secondary fibrinolysis elevates D-dimer.
Comprehensive 100-Question Exam with Rationales 100% Guarantee Pass Edition
