Which lymphatic vessel drains lymph from the right upper limb and the right side of the head and thorax?
Right lymphatic duct
✓
Thoracic duct
Cisterna chyli
Lacteal
Correct Answer
Right lymphatic duct
The right lymphatic duct collects lymph from the upper right quadrant of the body and empties it into the right subclavian vein. The thoracic duct drains the rest of the body, including the left side and everything below the diaphragm. The cisterna chyli is the saclike start of the thoracic duct in the abdomen. A lacteal is a lymphatic capillary in an intestinal villus.
Category: Lymphatic Anatomy
Question 2
Which lymphatic capillaries in the villi of the small intestine absorb dietary lipids?
Arterioles
Lacteals
✓
Venules
Sinusoids
Correct Answer
Lacteals
Lacteals are specialized lymphatic capillaries in intestinal villi that take up absorbed fats and fat-soluble vitamins. Arterioles are small arteries that deliver blood, not lymph. Venules are small veins that collect blood from capillary beds. Sinusoids are leaky blood capillaries found in organs such as the liver.
Category: Lymphatic Anatomy
Question 3
In which organ do immature T lymphocytes finish their development and selection?
Spleen
Bone marrow
Thymus
✓
Lymph node
Correct Answer
Thymus
Immature T cells leave the bone marrow and travel to the thymus, where they mature and undergo positive and negative selection. The spleen is a secondary lymphoid organ that filters blood. Bone marrow produces lymphocytes and is where B cells mature. Lymph nodes are secondary organs where mature lymphocytes meet antigens.
Category: Lymphatic Anatomy
Question 4
Which region of the spleen removes worn-out erythrocytes and microbes from the blood?
White pulp
Germinal center
Hilum
Red pulp
✓
Correct Answer
Red pulp
The red pulp is the blood-filtering tissue of the spleen, where macrophages remove aging red blood cells and pathogens. White pulp is lymphoid tissue around central arterioles where adaptive immune responses are launched. A germinal center is a site of dividing B cells within a lymphoid follicle. The hilum is where vessels enter and leave the organ.
Category: Lymphatic Anatomy
Question 5
Which white blood cells are the most numerous phagocytes recruited from the blood early in acute inflammation?
Neutrophils
✓
Eosinophils
Basophils
Lymphocytes
Correct Answer
Neutrophils
Neutrophils are the most abundant leukocytes and are the first phagocytes to pour into infected tissue, where they are the main pathogen killers of acute inflammation. Eosinophils mainly target parasites. Basophils release histamine and other mediators rather than acting as major phagocytes. Lymphocytes carry out specific immune responses and are not phagocytes.
Category: Innate Defenses
Question 6
What are the resident macrophages of the liver called?
Microglia
Kupffer cells
✓
Alveolar macrophages
Langerhans cells
Correct Answer
Kupffer cells
Kupffer cells are macrophages that line the liver sinusoids and engulf bacteria and debris arriving from the intestine. Microglia are the phagocytic cells of the central nervous system. Alveolar macrophages are the phagocytes of the lung air sacs. Langerhans cells are dendritic cells of the epidermis.
Category: Innate Defenses
Question 7
Which complement fragment binds to a pathogen's surface and marks it for phagocytosis?
C3a
C5a
C3b
✓
C9
Correct Answer
C3b
C3b attaches to microbial surfaces and acts as an opsonin, making the pathogen easier for phagocytes to recognize and engulf. C3a is a small fragment that diffuses away and promotes inflammation. C5a is a fragment that attracts phagocytes. C9 is a component of the membrane attack complex that forms pores.
Category: Innate Defenses
Question 8
Which proteins do virus-infected cells secrete to signal neighboring cells to produce antiviral proteins?
Prostaglandins
Perforins
Granzymes
Interferons
✓
Correct Answer
Interferons
Interferons are released by virus-infected cells and induce nearby cells to make proteins that interfere with viral replication. Prostaglandins are lipid mediators that cause vasodilation and pain in inflammation. Perforins are pore-forming proteins released by killer cells. Granzymes are enzymes that enter target cells and trigger apoptosis.
Category: Innate Defenses
Question 9
Antigen displayed on MHC class I molecules is recognized by which cells?
Cytotoxic T cells
✓
Helper T cells
Regulatory T cells
Plasma cells
Correct Answer
Cytotoxic T cells
MHC class I molecules present intracellular antigens, such as viral proteins, and are recognized by CD8 cytotoxic T cells that then kill the infected cell. Helper T cells recognize antigen on MHC class II molecules. Regulatory T cells are CD4 cells that suppress other T cell responses. Plasma cells secrete antibodies and do not use T cell receptors.
Category: T Lymphocytes
Question 10
Which lymphocytes carry CD4 and use cytokines to activate B cells and macrophages?
Natural killer cells
Helper T cells
✓
Cytotoxic T cells
Memory B cells
Correct Answer
Helper T cells
Helper T cells bear CD4, recognize antigen on MHC class II, and secrete cytokines that drive B cells to make antibody and activate macrophages. Natural killer cells are innate lymphocytes that kill abnormal cells directly. Cytotoxic T cells carry CD8 and destroy infected cells. Memory B cells are long-lived B cells that speed up later antibody responses.
Category: T Lymphocytes
Question 11
During T cell development, what is the removal of thymocytes that bind self-antigens called?
Positive selection
Clonal expansion
Negative selection
✓
Class switching
Correct Answer
Negative selection
Negative selection eliminates developing T cells that react with self-antigens, which helps establish self-tolerance and prevent autoimmunity. Positive selection keeps only thymocytes that can bind self-MHC molecules. Clonal expansion is the proliferation of a lymphocyte after it meets its antigen. Class switching is a B cell process that changes antibody class.
Category: T Lymphocytes
Question 12
Which antibody class circulates as a pentamer and is usually the first secreted in a primary response?
IgG
IgA
IgE
IgM
✓
Correct Answer
IgM
IgM is the largest antibody, a pentamer with ten antigen-binding sites, and it dominates the early primary response and strongly activates complement. IgG is a monomer that predominates later in the primary response and in secondary responses. IgA is the main antibody of mucosal secretions. IgE binds mast cells and drives allergic reactions.
Category: B Cells and Antibodies
Question 13
Which antibody class crosses the placenta to protect the fetus?
IgG
✓
IgM
IgA
IgD
Correct Answer
IgG
IgG is the only antibody class transported across the placenta, giving the fetus and newborn temporary protection. IgM is too large to cross the placenta. IgA protects mucosal surfaces and reaches the infant through breast milk. IgD serves mainly as a receptor on naive B cells.
Category: B Cells and Antibodies
Question 14
Activated B lymphocytes differentiate into which cells that secrete large amounts of antibody?
Memory B cells
Plasma cells
✓
Mast cells
Helper T cells
Correct Answer
Plasma cells
Plasma cells are terminally differentiated B cells specialized for secreting antibody. Memory B cells are long-lived cells that do not secrete large amounts of antibody but respond quickly on re-exposure. Mast cells are tissue cells that release histamine. Helper T cells secrete cytokines, not antibodies.
Category: B Cells and Antibodies
Question 15
A breastfed newborn protected by antibodies in its mother's milk has which type of immunity?
Natural active immunity
Artificial passive immunity
Natural passive immunity
✓
Artificial active immunity
Correct Answer
Natural passive immunity
Antibodies passed naturally from mother to infant give natural passive immunity, which is immediate but temporary and creates no memory. Natural active immunity follows the body's own response to an infection. Artificial passive immunity comes from injected antibodies such as immune globulin. Artificial active immunity results from vaccination.
Category: B Cells and Antibodies
Question 16
Which white blood cells are attracted to parasitic worms and release their granule contents onto the parasite?
Neutrophils
Basophils
Monocytes
Eosinophils
✓
Correct Answer
Eosinophils
Eosinophils are drawn to helminth infections by T cell cytokines and can bind IgE-coated worms, releasing toxic granule proteins onto them. Neutrophils are the main phagocytes against bacteria. Basophils release histamine in allergic reactions. Monocytes circulate in blood and become macrophages in tissues.
Category: Pathogen Responses
Question 17
Which feature of the influenza virus means a new vaccine must be produced for each flu season?
Its surface antigens keep changing
✓
It destroys helper T cells
It survives inside macrophages
It hides inside red blood cells
Correct Answer
Its surface antigens keep changing
Influenza surface proteins change through mutation and gene reassortment, so memory from earlier strains or vaccines may no longer recognize the new virus. Destroying helper T cells is how HIV defeats immunity. Surviving inside macrophages is how tuberculosis bacteria persist in the body. Hiding inside red blood cells describes the malaria parasite, not influenza.
Category: Pathogen Responses
Question 18
Which antibody class binds to mast cells and triggers the immediate reactions of hay fever and anaphylaxis?
IgG
IgE
✓
IgM
IgA
Correct Answer
IgE
IgE attaches to receptors on mast cells, and when allergen cross-links it, the mast cells degranulate within minutes in a type I hypersensitivity. IgG mediates type II and type III reactions and does not drive immediate allergy. IgM is the first antibody of a primary response. IgA protects mucosal surfaces.
Category: Immune Disorders
Question 19
In which autoimmune disease do antibodies target acetylcholine receptors at neuromuscular junctions?
Graves' disease
Type 1 diabetes
Myasthenia gravis
✓
Rheumatoid arthritis
Correct Answer
Myasthenia gravis
In myasthenia gravis, autoantibodies against acetylcholine receptors impair neuromuscular transmission and cause muscle weakness. Graves' disease involves antibodies that stimulate the TSH receptor. Type 1 diabetes results from immune destruction of pancreatic beta cells. Rheumatoid arthritis is chronic autoimmune inflammation of the joints.
Category: Immune Disorders
Question 20
Which molecules on donor cells are the main cause of transplant rejection when they differ from the recipient's?
Complement proteins
Fc receptors
Toll-like receptors
MHC molecules
✓
Correct Answer
MHC molecules
MHC molecules are highly variable between people, so foreign donor MHC provokes a strong T cell attack on the graft, which is why donors and recipients are matched for them. Complement proteins are circulating plasma proteins, not the cell-surface markers that identify tissue as foreign. Fc receptors bind the tail region of antibodies. Toll-like receptors are innate receptors that recognize microbial molecules.
Category: Transplant Immunology