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 cells are involved in the adaptive immunity, acquired immunity and specific defence?

  1. B cells

  2. T cells

  3. Antigen presenting cells

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Adaptive (acquired) immunity involves B cells, T cells, and antigen-presenting cells (APCs like dendritic cells, macrophages). B cells produce antibodies, T cells mediate cellular immunity and help B cells, and APCs process and present antigen to activate lymphocytes. All three cell types are essential components of the adaptive immune system.

Multiple choice

At cellular level, which of the following cells are primarily responsible for specificity?

  1. Cytotoxic T cells

  2. Hypervariable regions in domains of B cells

  3. The major histocompatibility complex

  4. Specific T cell receptors
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The hypervariable regions in the variable domains of antibodies (produced by B cells) are directly responsible for antigen specificity. These complementarity-determining regions (CDRs) form the antigen-binding site. While T cell receptors and MHC molecules are involved in immune recognition, the antibody hypervariable regions are the primary source of specificity at the molecular level.

Multiple choice

'Dextran' is used in the case of

  1. blood clotting

  2. bleeding

  3. plasma extension

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

Dextran is a volume expander used to increase blood volume.

Multiple choice

Monoclonal antibodies differ from polyclonal antibodies in their property of reacting with _____.

  1. specific epitope

  2. specific antigen

  3. specific clones of cells

  4. specific paratope

  5. all of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Specific epitope : monoclonal antibody has a single binding site for specific portion of a macromolecular antigen called epitope, whereas polyclonal antibodies have heterogeneous collection of binding sites for different epitope.

Multiple choice

Class switching takes place in ____ .

  1. the Pro-B cell

  2. the Pre-B cell

  3. immune B cell

  4. activated B cell

  5. plasma cell
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Activated B cell. Class switching is a process by which the isotype of the Abs produced in response to an Ag change as the humoral response proceeds. Different cytokine is induced switching to different antibody classes, enabling the immune system to respond in the most effective ways to different types of microbe. Activated (mature) B cell IgM+ IgD undergoes class switching by induced recombination of switch (S) region such that the VDJ primary RNA is spliced onto the RNA from the downstream C gene, producing a heavy chain with a new constant region and therefore a new class of Ig.

Multiple choice

The T-cell receptors can bind to antigenic peptide ____ .

  1. only in the free form

  2. only when loaded on to MHC

  3. only when bound to hapten

  4. only when bound to antibody

  5. all of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Only when loaded on to MHCT,  cell use TCR to recognize peptide Ag displayed by MHC on antigen presenting .cells.

Multiple choice

The tuberculin skin test is an example of _____.

  1. type IV delayed hypersensitivity

  2. allergy reaction

  3. serum sickness

  4. precipitation reaction

  5. agglutination reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Type IV delayed hypersensitivity. The tuberculin skin test (TST) is an example of type IV hypersensitivity. The test is done by injecting small amount of tuberculin purified protein derivative (PPD) under the top layer of skin. The response in Mycobacterium tuberculosis exposed individual begins within 8 hours  and a reddened area surrounds the injection site becomes indurate (firm and hard) within 12-24 hrs.  The TH1 cell that migrates to the injection site is responsible for the indurations.

Multiple choice

Which one of the following acts as C3 convertase in this particular pathway?

The alternative pathway of complement activation is triggered when a breakdown product of C3 hydrolysis, C3b is deposited on the surface of a microbe. Next step in this pathway is to form C3 convertase which enzymatically breaks down more C3.

  1. C3bBb

  2. C3bBbC3b

  3. C3a

  4. C4b2a

  5. C1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

C3bBb. The microbe-bounded C3b becomes substrate for the binding of another protein called Factor B, which is broken down by a plasma membrane to generate the Bb fragment. This fragment remain attached to C3b and the resulting C3bBb acts as C3 convertase in alternative pathway.

Multiple choice

Choose the correct match:

P. Eosinophil 1. An antigen presenting cell that is not phagocytic.
Q. Kuffer Cell 2. Generally first cell to arrive at the site of inflammation.
R. Dendrite Cell 3. Macrophages found in liver.
S. Mast Cell 4. Phagocytic cell important in the body’s defense against parasitic organisms.
5. Type I hypersensitivity.

  1. P - 4, Q - 3, R - 1, S - 5

  2. P - 4, Q - 3, R - 2, S - 1

  3. P - 5, Q - 1, R - 2, S - 4

  4. P - 2, Q - 3, R - 1, S - 4

  5. P - 5, Q - 1, R - 3, S - 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eosinophil is a phagocytic cell important in the body’s defense against parasitic organism. Kuffer cell is one type of tissue macrophages found in liver.  Dendritic cell is an antigen presenting cell that is not phagocytic.  Mast cell is associated with type I hypersensitivity.  Degranulation of mast cell occur in type I hypersensitivity.