Biology

Human Immunity and Blood

2,051 Questions

Human immunity and blood questions cover the physiological mechanisms protecting the body against diseases and the components of blood. Topics include blood groups, cell mediated immunity, monoclonal antibodies, and blood coagulation. These biology topics frequently appear in general science sections of competitive exams.

Blood groupsCell mediated immunityMonoclonal antibodiesBlood coagulationCancer immunology

Human Immunity and Blood Questions

Multiple choice

Which of the following is responsible for the production of histamine?

  1. B cells

  2. T cells

  3. Mast cells

  4. Neutrophils
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mast cells are responsible for the production of histamine, a chemical mediator that promotes inflammation and allergic reactions.

Multiple choice

What is the role of the Peyer's patches in the immune system?

  1. Production of antibodies

  2. Maturation of T cells

  3. Filtration of blood

  4. Sampling of intestinal antigens
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Peyer's patches are lymphoid tissues located in the small intestine that sample intestinal antigens and initiate immune responses.

Multiple choice

Which of the following is not a component of the classical complement pathway?

  1. C3

  2. C4

  3. C1q

  4. Factor B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Factor B is a component of the alternative complement pathway, not the classical pathway.

Multiple choice

What is the role of C3 convertase in the complement cascade?

  1. Cleaves C3 into C3a and C3b

  2. Activates C5 to form C5a and C5b

  3. Binds to foreign cell surfaces

  4. Initiates the assembly of the membrane attack complex
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

C3 convertase is an enzyme complex that cleaves C3 into C3a and C3b, initiating the formation of the membrane attack complex.

Multiple choice

Which complement protein is responsible for opsonization, enhancing phagocytosis by immune cells?

  1. C3a

  2. C3b

  3. C4

  4. C5a
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

C3b is the complement protein that binds to foreign cell surfaces, marking them for phagocytosis by immune cells.

Multiple choice

What is the function of the membrane attack complex (MAC) in the complement cascade?

  1. Activates the alternative complement pathway

  2. Promotes inflammation through anaphylatoxins

  3. Forms pores in the cell membrane, leading to cell lysis

  4. Binds to immune cells to initiate phagocytosis
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The membrane attack complex (MAC) forms pores in the cell membrane of foreign cells, causing cell lysis and destruction.

Multiple choice

Which complement protein is involved in the regulation of the complement cascade, preventing excessive activation?

  1. C1 inhibitor

  2. Factor H

  3. C4 binding protein

  4. C5 convertase inhibitor
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

C1 inhibitor is a regulatory protein that controls the classical complement pathway by inhibiting the activity of C1, preventing excessive activation.

Multiple choice

What is the role of C5a in the complement system?

  1. Activates neutrophils and macrophages

  2. Promotes inflammation through mast cell degranulation

  3. Inhibits the alternative complement pathway

  4. Binds to foreign cell surfaces to initiate opsonization
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

C5a is a complement protein that activates neutrophils and macrophages, promoting inflammation and enhancing phagocytosis.

Multiple choice

Which complement protein is involved in the formation of the C5 convertase complex?

  1. C3a

  2. C4b

  3. C5

  4. C6
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

C4b, along with C2a, forms the C5 convertase complex, which cleaves C5 into C5a and C5b.

Multiple choice

What is the role of properdin in the alternative complement pathway?

  1. Activates C3 convertase

  2. Stabilizes the C3 convertase complex

  3. Inhibits the classical complement pathway

  4. Binds to foreign cell surfaces to initiate opsonization
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Properdin is a protein that stabilizes the C3 convertase complex in the alternative complement pathway, enhancing its activity and promoting complement activation.

Multiple choice

Which complement protein is responsible for the generation of anaphylatoxins, such as C3a and C5a?

  1. C1q

  2. C3

  3. C4

  4. C5
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

C5 is the complement protein that undergoes cleavage to generate anaphylatoxins, including C3a and C5a, which have various inflammatory and immune-modulating effects.

Multiple choice

What is the role of C3aR and C5aR in the complement system?

  1. Inhibit the alternative complement pathway

  2. Bind to foreign cell surfaces to initiate opsonization

  3. Activate neutrophils and macrophages

  4. Regulate the activity of C3 convertase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

C3aR and C5aR are receptors for C3a and C5a, respectively. When activated, these receptors trigger various responses, including the activation of neutrophils and macrophages, promoting inflammation and phagocytosis.

Multiple choice

Which complement protein is involved in the assembly of the membrane attack complex (MAC)?

  1. C3b

  2. C4b

  3. C5b

  4. C6
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

C5b is the complement protein that initiates the assembly of the membrane attack complex (MAC) by binding to C6 and subsequent complement proteins, leading to the formation of pores in the cell membrane.

Multiple choice

What is the role of factor D in the alternative complement pathway?

  1. Activates C3 convertase

  2. Cleaves C5 into C5a and C5b

  3. Stabilizes the C5 convertase complex

  4. Binds to foreign cell surfaces to initiate opsonization
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Factor D is a serine protease that activates C3 convertase in the alternative complement pathway, leading to the cleavage of C3 into C3a and C3b.

Multiple choice

Which complement protein is responsible for the formation of the C3 convertase complex in the classical complement pathway?

  1. C1q

  2. C4b

  3. C2a

  4. C3b
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

The C3 convertase complex in the classical complement pathway is formed by the binding of C4b to C2a, leading to the cleavage of C3 into C3a and C3b.