Q: Which of the following equations correctly represents the inheritance of ABO blood groups, where A and B are dominant to O?

$$AA \times OO \rightarrow 100\% AO$$

Question 1

Which of the following best describes the function of the Membrane Attack Complex (MAC) in the complement cascade?

Accepted Answer

It forms pores in the plasma membrane of target cells, leading to osmolysis and cell lysis.

Question 2

A patient with blood type O- requires a blood transfusion. Which of the following donor blood types is compatible?

Accepted Answer

O-

Question 3

Which of the following steps is common to all three complement activation pathways (classical, lectin, and alternative)?

Accepted Answer

Cleavage of C3 into C3a and C3b

Question 4

A RhD- mother is pregnant with her second RhD+ child. She did not receive RhoGAM after her first pregnancy. What is the most likely outcome for the fetus?

Accepted Answer

The fetus is at risk for hemolytic disease of the newborn due to maternal anti-RhD antibodies.

Question 5

Which immunoglobulin class is primarily responsible for immediate hypersensitivity reactions such as anaphylaxis?

Accepted Answer

IgE

Question 6

A person with blood type AB+ can safely receive blood from which of the following donors?

Accepted Answer

All blood types

Question 7

Which of the following best explains why red blood cells (RBCs) do not cause rejection in organ transplantation?

Accepted Answer

RBCs do not express MHC I proteins.

Question 8

Which of the following is a direct result of complement activation during an incompatible blood transfusion?

Accepted Answer

Clumping and lysis of donor RBCs

Question 9

Which of the following equations correctly represents the inheritance of ABO blood groups, where A and B are dominant to O?

Accepted Answer

$$AA 	imes OO ightarrow 100\% AO$$

Question 10

Which of the following best describes the role of antigen-presenting cells (APCs) in linking innate and adaptive immunity?

Accepted Answer

They present processed antigens on MHC II molecules to activate T helper cells.

Question 11

A patient experiences a rapid allergic reaction after exposure to pollen. Which sequence of events best explains this response?

Accepted Answer

IgE binds to mast cells, allergen cross-links IgE, mast cell degranulation, histamine release

Question 12

Which of the following ions and molecules move into the cell through the MAC, leading to cell lysis?

Accepted Answer

$$Ca^{2+}$$, $$Na^+$$, and $$H_2O$$

Question 13

Which of the following best explains why a person with blood type A forms anti-B antibodies?

Accepted Answer

Exposure to bacterial and food antigens early in life

Question 14

Which of the following is a key difference between B cell activation with and without T helper (TH) cells?

Accepted Answer

Activation with TH cells produces long-lived plasma cells and IgG antibodies; without TH cells produces short-lived plasma cells and IgM antibodies.

Question 15

Which of the following best describes the role of interferon-α (IFN-α) during a viral infection?

Accepted Answer

It induces an antiviral state in neighboring cells by inhibiting protein synthesis and viral replication.

Question 16

A patient with blood type B- receives blood from a donor with blood type B+. What is the most likely immune response?

Accepted Answer

The recipient may develop anti-RhD antibodies after sensitization, leading to hemolysis in future exposures.

Question 17

Which of the following best explains why the secondary immune response to a viral infection is faster and stronger than the primary response?

Accepted Answer

Memory B cells and preexisting antibodies facilitate rapid neutralization and opsonization of the virus.

The Immune System: Complement Cascade, Blood Groups, and Hypersensitivity

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