MLT GlobeDOH exam preparation (Abu Dhabi) – page 10
700 practice MCQs for the DOH medical laboratory exam. Level: Basic to intermediate.
The lymphedema of elephantiasis in lymphatic filariasis is due mainly to:
Adult worms and inflammatory reactions damage and block lymphatics, causing lymph stasis, fibrosis and swelling. Circulating microfilariae alone cause little disease.
For which parasite is an animal (the domestic cat and other felids) the definitive host?
Sexual reproduction of T. gondii occurs only in the intestine of felids, which shed oocysts. The Entamoeba species and Giardia have direct life cycles in humans.
When a bone marrow aspirate from kala-azar is cultured on NNN medium, which form grows?
At 22 to 26 C in culture, amastigotes transform into flagellated promastigotes, the same form seen in the sandfly. Amastigotes are seen in tissue smears.
In the life cycle of Toxoplasma gondii, humans act as:
Humans harbor tachyzoites and tissue cysts only; the sexual cycle and oocyst shedding occur in cats (the definitive host).
The normal habitat of adult Ascaris lumbricoides is the:
Adults live free in the lumen of the jejunum and ileum. They may migrate to the appendix or bile duct, but this is abnormal.
Protozoa formerly grouped in the class Mastigophora move by means of:
Mastigophora are the flagellates, such as Giardia, Trichomonas and trypanosomes. Cilia are found in ciliates and pseudopodia in amoebae.
A non-pathogenic amoeba found in the human mouth, especially in gum disease, is:
E. gingivalis lives in the oral cavity and has no cyst stage. E. coli and E. hartmanni are non-pathogenic intestinal amoebae.
The most common form of extraintestinal amoebiasis is:
Trophozoites reach the liver through the portal vein, often forming a right-lobe abscess with anchovy-sauce pus. Lung and brain involvement is much less common.
Taenia saginata is best classified as a(n):
The adult beef tapeworm lives in the human small intestine; humans do not develop tissue larvae of T. saginata. Trematodes are flukes.
The most common form of asexual reproduction in protozoa is:
Most protozoa, such as amoebae and flagellates, divide into two daughter cells. Schizogony occurs in Apicomplexa, and conjugation is a sexual process in ciliates.
Breast-fed infants gain protection of the gut from which antibody in colostrum and milk?
Secretory IgA is the main antibody in milk and other secretions, protecting the infant's gut mucosa.
Which statement best describes an antibody?
Antibodies are glycoproteins that migrate mainly in the gamma-globulin region and are formed after exposure to immunogens.
After booster vaccination, a switch in immunoglobulin class usually changes antibody from:
In class switching, the variable region is kept but the heavy-chain constant region changes, typically from IgM to IgG.
Which antibody class triggers immediate allergic reactions?
IgE binds mast cells and basophils; allergen cross-linking releases histamine and other mediators.
The first physical barrier against invading microbes is the:
Intact skin and mucous membranes are the first line of innate defence.
Which is NOT part of innate defence?
Memory B-cell antibody responses are adaptive. Skin, interferons and phagocytes are innate.
Phagocytes destroy ingested microbes mainly through:
Lysosomes fuse with phagosomes, delivering enzymes and reactive oxygen species that destroy microbes.
Which cytokine is a classic endogenous pyrogen?
IL-1, with IL-6 and TNF, acts on the hypothalamus to cause fever. IL-2 promotes T-cell growth and IL-10 is anti-inflammatory.
Which statement about IgM is correct?
Pentameric IgM is a strong complement activator. IgG dominates secondary responses and crosses the placenta.
Which statement about IgA is correct?
Secretory IgA is abundant in milk, tears and saliva. IgE triggers anaphylaxis.