Biology

Human Immunity and Blood

2,096 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

What is the primary cytotoxic mechanism employed by NK cells?

  1. Antibody-mediated cytotoxicity

  2. Complement-mediated cytotoxicity

  3. Fas-mediated apoptosis

  4. Perforin and granzyme-mediated cytotoxicity
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

NK cells release perforin and granzymes, which are cytotoxic molecules that form pores in the target cell membrane, leading to cell lysis and apoptosis.

Multiple choice

Which cytokine is primarily responsible for NK cell activation?

  1. Interferon-gamma (IFN-γ)

  2. Interleukin-2 (IL-2)

  3. Interleukin-4 (IL-4)

  4. Tumor necrosis factor-alpha (TNF-α)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

IL-2 is a cytokine that plays a critical role in NK cell activation and proliferation. It binds to the IL-2 receptor on NK cells, triggering intracellular signaling pathways that promote cytotoxicity.

Multiple choice

Which molecule is expressed on healthy cells and recognized by NK cells to prevent self-destruction?

  1. MHC class I molecules

  2. MHC class II molecules

  3. CD45

  4. CD56
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Healthy cells express MHC class I molecules, which are recognized by inhibitory receptors on NK cells. This interaction prevents NK cells from attacking and destroying healthy cells, a process known as self-tolerance.

Multiple choice

What is the term used to describe the ability of NK cells to distinguish between healthy and infected or cancerous cells?

  1. Immune surveillance

  2. Immune tolerance

  3. Immune memory

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

Immune recognition refers to the ability of NK cells to differentiate between healthy and infected or cancerous cells based on specific markers or ligands expressed on their surfaces.

Multiple choice

Which signaling pathway is activated in NK cells upon target cell recognition?

  1. MAPK pathway

  2. PI3K pathway

  3. Jak-STAT pathway

  4. NF-κB pathway
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The PI3K (Phosphoinositide 3-Kinase) pathway is activated in NK cells upon target cell recognition. This pathway regulates various cellular processes, including cell activation, proliferation, and cytotoxicity.

Multiple choice

What is the role of NK cells in regulating adaptive immune responses?

  1. They suppress T cell activation

  2. They promote B cell differentiation

  3. They enhance antibody production

  4. They stimulate dendritic cell maturation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

NK cells can stimulate the maturation and activation of dendritic cells, which are antigen-presenting cells that play a crucial role in initiating adaptive immune responses.

Multiple choice

Which transcription factor is essential for NK cell development and function?

  1. T-bet

  2. GATA-3

  3. RORγt

  4. FoxP3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

T-bet (T-box transcription factor expressed in T cells) is a key transcription factor that regulates NK cell development, maturation, and cytotoxic function.

Multiple choice

What is the term used to describe the phenomenon where NK cells become anergic or hyporesponsive after prolonged exposure to target cells?

  1. NK cell exhaustion

  2. NK cell tolerance

  3. NK cell anergy

  4. NK cell senescence
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

NK cell exhaustion refers to the state of functional impairment and hyporesponsiveness that can occur in NK cells after prolonged exposure to target cells or chronic stimulation.

Multiple choice

Which receptor on NK cells is involved in the recognition of antibody-coated target cells?

  1. FcγRIIIa (CD16)

  2. KIR (Killer cell immunoglobulin-like receptor)

  3. NKG2D (Natural cytotoxicity triggering receptor 2)

  4. CD56 (Neural cell adhesion molecule)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

FcγRIIIa (CD16) is an activating receptor expressed on NK cells that binds to the Fc portion of antibodies bound to target cells, triggering antibody-dependent cell-mediated cytotoxicity (ADCC).

Multiple choice

Which cytokine is produced by NK cells that can inhibit tumor growth and angiogenesis?

  1. Interferon-gamma (IFN-γ)

  2. Interleukin-4 (IL-4)

  3. Interleukin-10 (IL-10)

  4. Tumor necrosis factor-alpha (TNF-α)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

NK cells produce Interferon-gamma (IFN-γ), a cytokine that has anti-tumor effects by inhibiting tumor cell proliferation, inducing apoptosis, and suppressing angiogenesis.

Multiple choice

Which type of immune response is responsible for attacking and destroying infected cells?

  1. Humoral immune response

  2. Cell-mediated immune response

  3. Innate immune response

  4. Adaptive immune response
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The cell-mediated immune response is responsible for attacking and destroying infected cells. It involves the activation of T cells, which can directly kill infected cells or release chemicals that attract other immune cells to the site of infection.

Multiple choice

Which type of immune response involves the production of antibodies?

  1. Humoral immune response

  2. Cell-mediated immune response

  3. Innate immune response

  4. Adaptive immune response
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The humoral immune response involves the production of antibodies, which are proteins that can bind to and neutralize pathogens. Antibodies are produced by B cells, which are activated by antigens.

Multiple choice

Which type of immune cell is responsible for producing memory cells?

  1. T cells

  2. B cells

  3. Macrophages

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

B cells are responsible for producing memory cells, which are long-lived cells that can quickly respond to a pathogen that the body has encountered before.

Multiple choice

Which type of immune cell is responsible for releasing histamine and other inflammatory mediators?

  1. T cells

  2. B cells

  3. Macrophages

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

Mast cells are responsible for releasing histamine and other inflammatory mediators, which are involved in the inflammatory response.

Multiple choice

What is the role of the spleen in the immune system?

  1. To produce antibodies

  2. To mature T cells

  3. To store immune cells

  4. To filter blood
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The spleen is responsible for filtering blood and removing old or damaged red blood cells, as well as foreign particles and pathogens.