A newborn’s intact skin and mucosal surfaces prevent pathogen entry before immune cells are activated. Which immune defense line is being tested?
A. Adaptive immunity
B. Innate immunity
C. Physical barriers
D. Plasma antibodies

C. Physical barriers

A patient with a splinter develops rapid neutrophil and macrophage activity before antigen-specific lymphocytes expand. Which defense line is primarily active?
A. Innate immune system
B. Adaptive immune system
C. Physical barrier system
D. Humoral memory system

A. Innate immune system

A vaccine generates antigen-specific lymphocyte memory that improves future responses. Which defense line does this represent?
A. Physical barriers
B. Innate immunity
C. Monocyte circulation
D. Adaptive immunity

D. Adaptive immunity

The immune system is broadly divided into which two major groups?
A. Humoral and cellular
B. Innate and adaptive
C. Monocytes and lymphocytes
D. Plasma and tissue

B. Innate and adaptive

A macrophage surrounds a bacterium and traps it inside an intracellular pouch before digestion. What is the pouch called?
A. Lysosome
B. Endosome
C. Phagosome
D. Peroxisome

C. Phagosome

A macrophage internalizes a bacterium, then the bacterium-containing vesicle fuses with an enzyme-rich organelle. Which organelle fuses with it?
A. Ribosome
B. Golgi body
C. Nucleus
D. Lysosome

D. Lysosome

A macrophage engulfs a fungal particle and digests it after vesicle fusion with destructive enzymes. What is this overall process called?
A. Phagocytosis
B. Chemotaxis
C. Opsonization
D. Exocytosis

A. Phagocytosis

A hematopoietic stem cell divides into two daughter cells. One differentiates, while the other remains a stem cell. What property is demonstrated?
A. Somatic recombination
B. Self-renewal
C. Junctional diversity
D. Clonal deletion

B. Self-renewal

White blood cells are “white” rather than red because they lack which molecule?
A. Myosin
B. Albumin
C. Keratin
D. Hemoglobin

D. Hemoglobin

A blood cell destined to become a macrophage leaves bone marrow and enters circulation. What is it called at this stage?
A. Monocyte
B. Plasma cell
C. Mast cell
D. Reticulocyte

A. Monocyte

Monocytes remains in blood for how long before later becoming a macrophage?
A. 1-3 hours
B. 1-3 months
C. 1-3 days
D. 1-3 weeks

C. 1-3 days

A monocyte leaves circulation and enters infected lung tissue. What must happen before it becomes a macrophage?
A. It enters marrow
B. It enters tissue
C. It binds IgE
D. It secretes antibody

B. It enters tissue

A macrophage senses bacteria and releases signaling proteins that coordinate nearby immune cells. What are these proteins called?
A. Antigens
B. Immunoglobulins
C. Lysozymes
D. Cytokines

D. Cytokines

In immunology, the term “immunoglobulin” is synonymous with which molecule?
A. Cytokine
B. Antigen
C. Antibody
D. Complement

C. Antibody

A student remembers antibody classes using “______”

GAMED

A bacterial surface molecule triggers B cells to produce antibodies against it. What is that molecule called?
A. Cytokine
B. Receptor
C. Constant region
D. Antigen

D. Antigen

A patient develops high levels of circulating antibodies after infection. Which cells directly produce these antibodies?
A. Helper T cells
B. Plasma B cells
C. Macrophages
D. Monocytes

B. Plasma B cells

An antibody contains two pairs of structurally different protein chains. Which pair is correct?
A. Alpha and beta chains
B. Variable and joining chains
C. Heavy and light chains
D. Fab and Fc chains

C. Heavy and light chains

A researcher mutates the antibody region that directly binds microbial surface molecules. Which region was altered?
A. Fab region
B. Constant region
C. Fc receptor
D. Heavy tail

A. Fab region

The Fab region of an antibody is best described as the region that binds which target?
A. Cytokines
B. Receptors
C. Lysosomes
D. Antigens

D. Antigens

A macrophage receptor interacts with the non-antigen-binding portion of an antibody. Which antibody region is involved?
A. Fab region
B. Constant region
C. Light chain
D. Junctional site

B. Constant region

A B cell switches from producing IgM to IgG while preserving antigen specificity. Which antibody region determines class?
A. Fab region
B. Light chain
C. Constant region
D. Phagosome region

C. Constant region

A B cell generates antibody diversity by recombining inherited DNA segments. Which gene segments are involved?
A. A, B, C, D
B. H, L, F, C
C. G, A, M, E
D. V, D, J, C

D. V, D, J, C

A developing B cell pastes different antibody gene segments together to generate many receptor possibilities. What is this strategy called?
A. Modular design
B. Clonal deletion
C. Antigen presentation
D. Cytokine signaling

A. Modular design

During antibody gene recombination, nucleotide bases are added or removed at segment junctions, creating extra variability. What is this called?
A. Somatic expansion
B. Class switching
C. Junctional diversity
D. Receptor editing

C. Junctional diversity

Why does the immune system use modular design and junctional diversity to make antibodies?
A. To reduce antigen exposure
B. To create massive diversity
C. To destroy stem cells
D. To prevent cytokine release

B. To create massive diversity

Roughly how many different antibodies are needed to protect against possible invaders?
A. 100 million
B. 100 thousand
C. 25 thousand
D. 20 million

A. 100 million

Humans generate millions of unique antibodies using only a ____ amount of DNA through a highly efficient process called ____ recombination

Humans generate millions of unique antibodies using only a limited amount of DNA through a highly efficient process called VDJ recombination

After a B cell creates its antibody “recipe,” where are small batches of antibody displayed?
A. Inside lysosomes
B. Within phagosomes
C. On the B-cell surface
D. Inside macrophages

C. On the B-cell surface

Surface antibodies on a B cell function as which receptor?
A. Fc receptor
B. B cell receptor
C. Cytokine receptor
D. Lysosome receptor

B. B cell receptor

On a B cell receptor, which region faces outward to search for matching antigen?
A. Fab region
B. Constant region
C. Heavy tail
D. Fc region

A. Fab region

The specific molecule that fits a B cell’s antigen-binding region is called what?
A. Junctional antigen
B. Constant antigen
C. Innate antigen
D. Cognate antigen

D. Cognate antigen

A naive B cell encounters the exact antigen fitting its surface receptor. What is the expected result?
A. Hemoglobin production
B. Macrophage maturation
C. B-cell proliferation
D. Lysosome destruction

C. B-cell proliferation

Following the initial encounter with its cognate antigen, it generally takes about ___ to ___ days for a naïve B cell to undergo massive clonal expansion and differentiate into antibody-secreting effector cells (plasma cells).

4 to 5 days

After finding its cognate antigen, a B cell expands into approximately how many clones?
A. 2,000 clones
B. 20,000 clones
C. 100,000 clones
D. 1 million clones

B. 20,000 clones

A plasma cell is working at maximum antibody-secreting capacity during an acute infection. How many antibodies can it produce per second?
A. 200
B. 2,000
C. 20,000
D. 100,000

B. 2,000

The main defensive role of antibodies against foreign invaders is best described as which function?
A. Destroy host cells directly
B. Mature inside thymus
C. Tag invaders for destruction
D. Form class I MHC

C. Tag invaders for destruction

A bacterium becomes coated with antibodies, making it easier for phagocytes to recognize and destroy it. What is this process called?
A. Neutralization
B. Opsonization
C. Proliferation
D. Presentation

B. Opsonization

A patient develops antibodies that bind viral particles before they infect respiratory epithelial cells. Which antibody type best describes this action?
A. Neutralizing antibody
B. Opsonizing antibody
C. Regulatory antibody
D. Memory antibody

A. Neutralizing antibody

A neutralizing antibody binds a viral particle outside a host cell. What is one major effect?
A. Blocks viral entry
B. Activates thymic cortex
C. Forms class II MHC
D. Produces beta chains

A. Blocks viral entry

A patient has circulating antibodies against an enveloped virus, but some virions have already entered epithelial cells and uncoated in the cytosol. Why can the antibodies not directly bind those intracellular virions?
A. Antibodies lack antigen specificity
B. Antibodies cannot cross intact membranes
C. Viruses destroy all immunoglobulins
D. Host cytosol contains no antigens

B. Antibodies cannot cross intact membranes

Antibodies primarily circulate in which body compartment?
A. Extracellular fluids
B. Cytosolic fluid
C. Nuclear matrix
D. Mitochondrial space

A. Extracellular fluids

Which location would normally contain circulating soluble antibodies?
A. Host cell cytosol
B. Viral nucleocapsid
C. Blood plasma
D. Mitochondrial matrix

C. Blood plasma

A virus successfully enters and uncoats inside a host cell without prior antibody binding. What protects it from direct antibody binding?
A. Its intracellular location
B. Its larger genome
C. Its bacterial capsule
D. Its thymic origin

A. Its intracellular location

A child with impaired thymic development has defective maturation of which immune cell type?
A. B cells
B. T cells
C. Monocytes
D. Macrophages

B. T cells

Which group correctly lists the three main T-cell types?
A. Killer, helper, regulatory
B. Plasma, memory, naive
C. Monocyte, macrophage, dendritic
D. IgG, IgA, IgM

A. Killer, helper, regulatory

Cytotoxic lymphocytes are another name for which T-cell type?
A. Helper T cells
B. Regulatory T cells
C. Killer T cells
D. Plasma T cells

C. Killer T cells

A T cell determines whether a host cell is infected by inspecting molecules displayed on the cell surface. What does it inspect?
A. Immunoglobulin
B. Hemoglobin
C. Cytokine receptor
D. MHC

D. MHC

T cells can indirectly “view” intracellular contents because cells display peptides using which molecule?
A. MHC
B. IgE
C. BCR
D. Lysosome

A. MHC

Most nucleated body cells use which MHC class to show intracellular material?
A. Class I MHC
B. Class II MHC
C. Class III MHC
D. Class IV MHC

A. Class I MHC

Killer T cells mainly inspect which MHC class?
A. Class II MHC
B. Class I MHC
C. Class III MHC
D. Class IV MHC

B. Class I MHC

A virally infected epithelial cell displays abnormal intracellular peptides. Which immune cell is most directly involved in checking it?
A. Helper T cell
B. Plasma B cell
C. Killer T cell
D. Regulatory B cell

C. Killer T cell

Certain immune cells display extracellular antigen fragments to helper T cells. What are these cells called?
A. Antigen-presenting cells
B. Antibody-secreting cells
C. Hemoglobin-lacking cells
D. Beta-microglobulin cells

A. Antigen-presenting cells

Antigen-presenting cells use which MHC class to communicate with helper T cells?
A. Class I MHC
B. Class II MHC
C. Class III MHC
D. Class IV MHC

B. Class II MHC

Helper T cells primarily assess infection in which environment through class II MHC?
A. Intracellular environment
B. Extracellular environment
C. Bone marrow niche
D. Thymic medulla

B. Extracellular environment

Class I MHC is structurally composed of one long chain plus which smaller chain?
A. Alpha chain
B. Beta chain
C. Delta chain
D. B2-microglobulin

D. B2-microglobulin

Which structure is part of class I MHC but not class II MHC?
A. B2-microglobulin
B. Alpha chain
C. Beta chain
D. Fab region

A. B2-microglobulin

Class II MHC is made of which two long chains?
A. Heavy and light
B. Alpha and beta
C. Fab and constant
D. Gamma and delta

B. Alpha and beta

Which statement correctly describes class I MHC?
A. One long chain
B. Two alpha chains
C. Two beta chains
D. Heavy and light chains

A. One long chain

Which statement correctly describes class II MHC structure?
A. One long chain
B. Two long chains
C. B2-microglobulin only
D. Fab and Fc regions

B. Two long chains

B cells and T cells are collectively called what?

Lymphocytes

After an infection is cleared, most expanded B and T cells undergo cell death. What are the surviving long-lived cells called?
A. Plasma cells
B. Memory cells
C. Stem cells
D. Monocytes

B. Memory cells

During a second exposure to the same pathogen, the adaptive immune system responds faster. Which cells mainly explain this?
A. Memory cells
B. Monocytes
C. Neutrophils
D. Macrophages

A. Memory cells

A vaccine works partly because some lymphocytes survive after the initial response. What is the main benefit of these cells?
A. Faster secondary response
B. Slower antigen recognition
C. Reduced MHC expression
D. Blocked antibody secretion

A. Faster secondary response