Cardiovascular Lymphatic Immunity Actual Exam 2026/2027
– Complete 50 Questions with Detailed Rationales | 100%
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SECTION A: Blood – Composition, Hemostasis & Blood Typing (Q1–Q10)
Q1: Which component of blood accounts for approximately 55% of total blood volume
and consists of water, plasma proteins, electrolytes, and dissolved solutes?
A. Plasma [CORRECT]
B. Buffy coat
C. Formed elements
D. Erythrocyte layer
Correct Answer: A
Rationale: Plasma is the liquid extracellular matrix making up about 55% of blood
volume, containing water, albumin, fibrinogen, globulins, and solutes. The buffy coat
(leukocytes and platelets) and erythrocyte layer together constitute the formed
elements.
Q2: A peripheral blood smear shows erythrocytes that lack a nucleus and most
organelles. What functional consequence does this produce?
A. The cells cannot bind oxygen at all
B. The cells rely on anaerobic glycolysis for energy and cannot synthesize replacement
proteins, limiting their lifespan to about 120 days [CORRECT]
C. The cells become too rigid to pass through capillaries
D. The cells survive indefinitely without repair
Correct Answer: B
Rationale: Without a nucleus, ribosomes, or mitochondria, mature RBCs cannot perform
protein synthesis or repair, so they accumulate damage and are removed after roughly
120 days. They still transport oxygen efficiently and remain flexible enough for capillary
transit.
Q3: A patient returns from international travel and is diagnosed with an intestinal
parasitic worm infection. Which leukocyte would be expected to be elevated on the
differential count?
,A. Basophils
B. Neutrophils
C. Lymphocytes
D. Eosinophils [CORRECT]
Correct Answer: D
Rationale: Eosinophils increase in response to parasitic infections (especially
helminths) and allergic reactions. Neutrophils rise in bacterial infections, basophils
mediate histamine release, and lymphocytes respond to viral infections and adaptive
immunity.
Q4: In a patient with a chronic bacterial infection, monocyte counts rise. What role do
these cells play after they migrate into damaged tissues?
A. They differentiate into macrophages that phagocytize pathogens and cellular debris
[CORRECT]
B. They release histamine to trigger vasodilation
C. They produce antibodies against bacterial toxins
D. They destroy parasitic worms by toxic granule release
Correct Answer: A
Rationale: Monocytes circulate briefly and then enter tissues, where they enlarge and
differentiate into macrophages — major phagocytes of innate immunity. Histamine
release is a basophil function, antibodies come from B-cell-derived plasma cells, and
antiparasitic granule release is eosinophil activity.
Q5: A patient with thrombocytopenia develops pinpoint skin hemorrhages (petechiae)
because her platelet count is low. Platelets are membrane-bound fragments released
into the bloodstream by which parent cell?
A. Myeloblast
B. Reticulocyte
C. Megakaryocyte [CORRECT]
D. Lymphoblast
Correct Answer: C
Rationale: Megakaryocytes in the red bone marrow extend cytoplasmic processes that
fragment into platelets. Myeloblasts and lymphoblasts are leukocyte precursors, and
reticulocytes are immature erythrocytes.
Q6: A laboratory assay initiates clotting by adding tissue factor (thromboplastin) directly
to a plasma sample. Which coagulation pathway is being activated?
A. The intrinsic pathway
B. The extrinsic pathway [CORRECT]
C. The fibrinolytic pathway
, D. The complement pathway
Correct Answer: B
Rationale: The extrinsic pathway is triggered when damaged tissues expose tissue
factor to plasma, rapidly leading to factor X activation. The intrinsic pathway is instead
initiated by trauma inside the vessel and contact with exposed collagen.
Q7: A patient experiencing an acute ischemic stroke is given tissue plasminogen
activator (tPA). What is the mechanism of action of this drug?
A. It stimulates platelet plug formation at the injury site
B. It activates factor XII to accelerate the intrinsic pathway
C. It converts plasminogen into plasmin, which digests the fibrin meshwork of the clot
[CORRECT]
D. It inhibits vitamin K to block clotting factor synthesis
Correct Answer: C
Rationale: tPA activates plasminogen to form plasmin, the enzyme that breaks down
fibrin and dissolves the pathological clot. It does not promote platelet activity, trigger
factor XII, or block vitamin K–dependent factor synthesis (that is warfarin's
mechanism).
Q8: A person with type O negative blood is considered the universal red blood cell
donor. What is the immunological basis for this?
A. Their plasma contains no antibodies of any kind
B. Their red blood cells carry both A and B antigens
C. They can donate only to Rh-positive recipients
D. Their red blood cells lack the A, B, and D antigens, so no recipient antibodies can bind
them [CORRECT]
Correct Answer: D
Rationale: Because type O negative RBCs display neither A, B, nor D antigens, anti-A,
anti-B, and anti-D antibodies in any recipient have no target on the donor cells. The
donor's plasma antibodies are diluted in the recipient, and the RBC antigens — not
plasma antibodies — determine compatibility.
Q9: An Rh-negative mother who previously carried an Rh-positive fetus is now pregnant
with a second Rh-positive fetus. Why is this pregnancy at risk for hemolytic disease of
the newborn (erythroblastosis fetalis)?
A. Anti-D antibodies formed during the first exposure cross the placenta and agglutinate
and hemolyze the fetal Rh-positive red blood cells [CORRECT]
B. The fetus mounts an antibody attack against the mother's Rh-negative cells
C. ABO incompatibility destroys the fetal liver
D. The mother's blood has permanently converted to Rh-positive