MLT GlobeQCHP exam preparation (Qatar)
749 practice MCQs for the QCHP medical laboratory exam. Level: Intermediate.
Subject mix: Blood Banking 20%, Hematology 20%, Chemistry 20%, Immunology & Serology 15%, Bacteriology 13%, Parasitology 3%, Histo & Cyto Techniques 3%, Histopathology 2%, Mycology 2%, Virology 2%
The immune system is broadly divided into which two arms?
The primary division is innate versus adaptive immunity. Humoral and cell-mediated responses are subdivisions of the adaptive arm.
A single IgG molecule is made of how many polypeptide chains?
The basic immunoglobulin unit has two identical heavy and two identical light chains linked by disulfide bonds. Five refers to the number of units in pentameric IgM.
What needle size is standard for whole-blood donor collection?
A wide 16–17 gauge needle allows rapid flow into the bag and minimizes shear damage to red cells. Higher gauge numbers are narrower needles.
Which immunoglobulin class crosses the placenta and gives passive immunity to the newborn?
IgG is the only class transported across the placenta via neonatal Fc receptors. It also has four subclasses and is the most abundant serum immunoglobulin.
Giving a patient stored blood equal to or exceeding their whole blood volume within 24 hours is termed:
Massive transfusion is classically replacement of one blood volume (about 10 units in an adult) in 24 hours, bringing risks of dilutional coagulopathy, hypothermia and citrate toxicity.
Which test is NOT a universal mandatory screen for donated blood?
Every donated unit is screened for HIV, HBV (HBsAg) and HCV, plus syphilis. Schistosomiasis serology is not part of routine mandatory donor screening.
Why do antibodies and T-cell receptors bind antigens specifically?
Binding depends on the complementary fit of the binding site to the epitope through non-covalent forces. TCRs lack immunoglobulin light and heavy chains.
In a healthy adult, which immunoglobulin class has the highest serum concentration?
IgG makes up about 75–80% of serum immunoglobulin. IgA is second and IgE the lowest.
Which immunoglobulin class is present at the lowest serum concentration in normal adults?
IgE is present in trace amounts, much lower than IgD. Most IgE is bound to mast cells and basophils.
Failure of the immune system to distinguish self from non-self leads to:
Loss of self-tolerance produces autoimmune diseases.
Inherited defects in innate or adaptive immune components cause:
Primary immunodeficiency results from genetic defects in immune components, causing recurrent infections.
Which gastric factor kills most swallowed microorganisms?
Low pH from HCl destroys most ingested microbes. Hyaluronidase and haemolysin are bacterial virulence factors.
After migrating into tissue, a monocyte becomes a:
Monocytes enter tissues and mature into macrophages, e.g. Kupffer cells.
What is the main role of C5a in inflammation?
C5a is a strong chemoattractant for phagocytes.
Which is a feature of active acquired immunity?
Active immunity generates memory cells and lasts long. Maternal transfer and antibody injection are passive.
Giving diphtheria antitoxin to a patient provides:
Antitoxin provides preformed antibodies, giving immediate but temporary passive protection.
Which cytokine is secreted by T cells and activates macrophages and NK cells?
Interferon-gamma is produced by Th1 and NK cells and activates macrophages.
A patient develops an itchy vesicular rash 48 hours after wearing a nickel bracelet. Which arm of immunity mediates this reaction?
Allergic contact dermatitis is a delayed (type IV) reaction; hapten-modified proteins activate memory T cells, which peak at 48-72 h. Antibodies are not required.
Most clinical organ transplants, e.g. a kidney from an unrelated human donor, are classified as:
An allograft passes between genetically different members of the same species, so HLA mismatches can provoke rejection.
After an allogeneic stem-cell transplant, a patient develops rash, diarrhoea and raised liver enzymes. Graft-versus-host disease means:
In GVHD, immunocompetent donor T cells recognise host antigens as foreign, typically damaging skin, gut and liver. Recipient attack on the graft is rejection.