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

Autoimmune thrombocytopenic purpura (ITP) is characterised by

  1. an increase in platelet count

  2. a decrease in platelet count

  3. bone marrow abnormalities

  4. blister formation on the skin
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Autoimmune thrombocytopenic purpura is characterised by a decrease in platelet count. ITP is an autoimmune disease with antibodies detectable against several platelet surface antigens.

Multiple choice

Which of the following is not an action of adjuvants?

  1. They extend the presence of antigens in the blood.

  2. They activate macrophages and lymphocytes.

  3. They accelerate the division of immune cells.

  4. They support the production of cytokines.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Adjuvants do not accelerate the division of immune cells.

Multiple choice

Match the columns.

 
Phagocyte Function
1. NK cells a. Present antigens
2. Dendritic cells b. Anaphylaxis
3. Mast cells c. Attack and destroy tumor cells
4. Macrophages d. Scavengers
  1. 1. NK cells d. Scavengers
    2. Dendritic cells c. Attack and destroy tumor cells
    3. Mast cells a. Present antigens
    4. Macrophages b. Anaphylaxis
  2. 1. NK cells c. Attack and destroy tumor cells
    2. Dendritic cells a. Present antigens
    3. Mast cells b. Anaphylaxis
    4. Macrophages d. Scavengers
  3. 1. NK cells b. Anaphylaxis
    2. Dendritic cells d. Scavengers
    3. Mast cells a. Present antigens
    4. Macrophages c. Attack and destroy tumor cells
  4. 1. NK cells d. Scavengers
    2. Dendritic cells b. Anaphylaxis
    3. Mast cells c. Attack and destroy tumor cells
    4. Macrophages a. Present antigens
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is the correct match. Natural killer (NK cells) cells are leukocytes that attack and destroy tumor cells. Dendritic cells present antigens to T-cells. Mast cells are most often associated with allergy and anaphylaxis. Macrophages act as scavengers, ridding the body of worn-out cells and other debris.

Multiple choice

Protection against various microorganisms like bacteria, viruses, etc. inside the living cells is provided by which among the following components of the immune system?

  1. T-cells

  2. Antibodies

  3. C3b

  4. C1q

  5. Membrane-attack complex
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

T-lymphocytes are specialised for recognising peptides derived from intracellular infectious agents which are exhibited on the surface of an infected cell together with MHC class I & II molecules.

Multiple choice

Which among the following is required for transferring specific immunity to M. tuberculosis in mice?

  1. B-cells

  2. T-cells

  3. Macrophages

  4. Neutrophils

  5. IgG
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

T-cells are important for immunity to M. tuberculosis through the provision of Th1 cytokines such as IFN-gamma to activate macrophages containing the bacilli and perhaps also the participation of cytotoxic T-cells. The latter may kill macrophages which cannot be rescued by cytokines thereby releasing the bacteria to be taken up by fresh young macrophages which can be activated to become killers.

Multiple choice

The membrane attack complex is composed of a complex of four complement proteins (C5b, C6, C7 and C8) that bind to the outer surface of the plasma membrane. Individuals lacking C8 or C9 are more prone to get infected from

  1. Haemophilus influenzae

  2. Bacillus anthrax

  3. Vibrio cholerae

  4. Neisseria

  5. Listeria monocytogenes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The membrane attack complex containing C8 and C9 is important for destroying the Neisseria bacterium.

Multiple choice

Which of the following changes in the cell causes inflammation, which is a defensive reaction initiated by infection or tissue injury?

  1. Upregulation of adhesion molecules on endothelial cells and leukocytes

  2. Chemotaxis

  3. IL-8 release

  4. Phagocytosis

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

Up-regulation of P-selectin leads to binding to sialyl Lewisx on the neutrophil and causes rolling along the endothelium. Upregulation of PAF leads to firm binding to the receptor on the neutrophil and the cell is then subject to chemotactic attraction to pass through the endothelial cells.

Multiple choice

Mycobacterium tuberculosis cells growing in macrophages are filamentous and deficient in FtsZ rings, and are killed by which of the following constituents of defense mechanism?

  1. Complement

  2. Reactive oxygen and nitrogen intermediates

  3. Antibodies

  4. Cytotoxic T-cells

  5. Cytokines released from Th1 cells
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

These mechanisms come into play when the macrophage is activated. Other mechanisms, e.g. peptide defensins and cationic proteins may also contribute to killing.

Multiple choice

The extracellular bacteria are found outside the living cells and can be detected quite easily by the immune system because T-cells can come in contact with them. Extracellular bacteria are killed by which of the following phenomena occurring between the host and the bacteria?

  1. Secreting exotoxins

  2. Impeding inflammatory reactions

  3. Phagocytosis and complement

  4. Toxin neutralisation

  5. C-reactive protein
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Major killing of extracellular bacteria is through phagocytosis and intracellular killing. Complement aids opsonisation of bacteria to facilitate phagocytosis but may also be responsible for the bactericidal action of fresh serum containing antibody on Gram-negative bacteria.

Multiple choice

Which blood group is known as the universal donor?

  1. A

  2. B

  3. AB

  4. O

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Blood group O is known as the universal donor because individuals with type O blood can donate red blood cells to recipients of any blood type (A, B, AB, or O). This is because type O red blood cells lack both A and B antigens on their surface, preventing immune reactions. Type AB is the universal recipient, not donor. Types A and B can only donate to specific matching types.

Multiple choice

Macrophages are the body's first line of defense and have many roles.The protein present on the surface of macrophages is

  1. calnexin

  2. galectins

  3. calreticulin

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

Sialoadhesin is a cell adhesion molecule found on the surface of certain cells of the immune system called macrophages. It is found in especially high amounts on macrophages of the spleen, liver, lymph node, bone marrow, colon, and lungs. Also, in patients suffering from rheumatoid arthritis, the protein has been found in great amounts on macrophages of the affected tissues.

Multiple choice

Germinal centers are sites within secondary lymphoid organs where mature B lymphocytes are formed. During the bacterial infection of an eye the tingible bodies inside germinal center macrophages are

  1. DNA fragments

  2. Phagocytosed foreign antigen

  3. A sign of macrophage apoptosis

  4. Bacterial cell wall components are resistant to degradation

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

There is very extensive apoptotic cell death amongst the light zone centrocytes and the resultant DNA fragments are visible as 'tingible bodies' within the macrophages which have phagocytosed the apoptotic lymphocytes.