MLS Practice Exam Practice Questions
The McFarland Comparison Card shown in the illustration is used to:
Standardize concentrations of organisms Feedback -The McFarland comparison Card is used to create bacterial suspensions, especially for antimicrobial susceptibility (MIC) testing.
Which genotype is associated with alpha thalassemia minor?
-a/-a Feedback A deletion of two our of the 4 alpha gene loci results in alpha thalassemia minor. The deletion can either be heterozygous or homozygous, but both parents in this case must be missing one gene locus. —/aa is considered heterozygous, -a/aa is a silent carrior missing only one gene loci, —/-a is missing 3 gene loci, and —/— does not have any alpha gene loci present.
Given the following learning activity, "After the demonstration, the student will be able to prepare peripheral blood smears that meet the criteria in the procedure manual". What instructional aids would be the best choice to augment the activity?
video
What D variants has the best likelihood to receive D-positive RBCs without any adverse effects?
C in Trans to RHD -Patients with C in Trans in RHD possess complete D antigen structures. The allele that carries C is in trans from the allele carrying RHD. -Resulting the positive of the C antigen in the relationship to the D antigen interferes with the expression of the D antigen. -This can be a weakened
What organism is the most common cause of acute cystitis?
Escherichia coli -Acute cystitis is a bacterial infection of the bladder. -E. Coliu is a common urinary tract pathogen that is a frequent cause of acute cystitis and usually originate from the patient's own endogenous flora.
When performing the rosette test to screen for Fetal Maternal Hemorrhage, what is considered the correct combination to avoid false positives and/or false negatives?
Fetal cells D positive and mother is D negative Feedback The fetal cells must be D positive, and the mother must be D negative for the rosette test to be valid.
What is the purpose of the iodine that is used the Gram stain procedure?
Fixes the crystal violet to the cellular components of gram-positive bacteria Feedback Iodine is used a mordant to help the crystal violet stick to the cell walls of gram positive organisms.
What characteristic is found within May Hegglin Anomaly?
Giant platelets Feedback May Hegglin Anomaly will present with giant platelets along with inclusions that are similar in appearance to Dohle bodies and thrombocytopenia.
In which age group is Type I Hereditary Hemochromatosis (HH - the most common form) most likely to be initially detected based on clinical symptoms?
Middle aged adults -HH becomes symptomatic during middle age, and it is autosomal recessive gene defect resulting in excessive iron absorption in the GI tract.
Important applications of polymerase chain reaction (PCR) include what?
1. Amplification of DNA -PCR is a method that amplifies low levels of specific DNA sequences in a sample to higher levels of suitable for further analysis. 2. Identification of a target sequence - Qualitative PCR detects the presence or absence of a specific DNA product. 3. Synthesis of an anti-sense probe -Antisense RNA is a single-stranded RNA that is complementary to a messenger RNA (mRNA) strand transcribed within a cell.
What is the lower reference limit for semen volume according to the World Health Organization, WHO Laboratory Manual for the Examination and Processing of Human Semen, 5th edition?
1.5 mL
A sample of cerebrospinal fluid is diluted 1:100; the standard 9 squares of a hemocytometer were counted on each side for a total of 18 large squares. Slide 1 had 186 cells counted, and slide 2 had 184 cells counted.
2.06x10^(4) Feedback Cells/uL = (# of cells counted x dilution)/ (# of large squared counted x 0.1uL) Cells/uL = (370 x 100)/(18 x 0.1) Cells/uL = 2.06x10^(4)
How long does it take for plasma concentrations to reach steady state when a patient's dose is given at intervals of the drug's half-life?
5-7 half-lives Feedback As a patient is given drugs, the patient's plasma concentration reaches a steady state after 5-7 days. After 5-7 days the amount of drugs in the plasma has built up to a therapeutic concentration level.
What is considered an accrediting agency(ies) for quality and safety in the blood industry?
AABB Feedback AABB (American Association of Blood Banks) is an accrediting agency and compliance with their requirements is voluntary and evaluated by peer review.
Which of the following best describes the direct antiglobulin (DAT) test principle?
AHG (anti-human globulin) detects antibody already sensitized to red cells Feedback The principle of the DAT is to detect antibodies that are bound to the patient's red blood cells, this is a test of the red blood cell sensitization has taken place in-vivo.
What analyte should be increased in the presence of pancreatitis?
Amylase Feedback Increased serum amylase levels are associated with pancreatitis.
Hormonal variation throughout the menstrual cycle typically shows:
An abrupt rise in luteinizing hormone (LH) 3-36 hours prior to ovulation Feedback The LH surge is required for ovulation. In fact, 3-36 hours after the LH surge, the follicle releases an ovum, which is called ovulation.
The production of neutral 17-ketosteroids is a measure of what?
Androgen production Feedback 17-ketosteroids are metabolites of male steroid sex hormones or androgens, and other hormones released by a part of the adrenal gland in the males and females.
What is the term used to describe chest pain caused by inadequate supply of oxygen to heart myocardium?
Angina Feedback Angina - chest pain caused by an inadequate supply of oxygen to heart myocardium.
Which of the following substances can cause a false positive result for blood on the urine chemical reagent strip? a. Ascorbic acid b. Bleach in the collecting bottle c. High levels of nitrite d. High specific gravity
Bleach in the collecting bottle Feedback The presence of bleach in the urine collection container can lead to a false positive blood result on the chemical reagent strip. Bleach can trigger the color change normally associated with the presence of red blood cells or hemoglobin.
Where is the main site of action for monocytes after diapedesis?
Body tissues Feedback -Diapedsis is the process where blood cells pass through capillary walls. -Monocytes function in the immune system by responding to inflammation signals and moving to sites of infection in the tissues. -Once the monocytes have arrived, the monocytes divide and differentiate into macrophages and dendritic cells to elicit an immune response.
AIDS patients have an increased susceptibility to infection due to a decrease in which of the following?
CD4+ lymphocytes Feedback CD4+ cells aid in the immune system in attacking foreign antigens that cause infections. HIV mainly targets the CD4+ cells by using the virus glycoprotein to bind to the receptors on the lymphocyte
Central Tolerance in the human immune defense system operates by:
Clonal deletion of T cells and clonal edition of B cells. Feedback Central tolerance is characterized by the elimination of immature lymphocytes in primary lymph organs. It is controlled by a mechanism of clonal deletion of T cells and clonal editing of B cells
When AHG or Coombs serum is used to demonstrate that red blood cells are antibody coated in vivo, the procedure is termed:
Direct technique Feedback DAT is preformed in vivo sensitization of RBC's with IgG or complement molecules (AHG or Coombs cells, in other words). The IAT is performed to detect in vitro sesnitization of RBCs for antibody screening and compatibility testing purposes, but AHG or Coombs is not used.
The technologists in the urinalysis department received a sample for a microscopic examination. The image to the right shows the microscopic urinalysis. Which of the following conditions below would most closely match this patient's microscopic urinalysis morphology?
Glomomerulonephritis Feedback Glomerulonephritis is a type of kidney disease in which the glomerulus is damaged. Damage to the glomeruli causes blood and protein to be lost in the urine glomomerulonephritis.
Which substance acts as a mordant in the Gram stain process?
Gram's iodine Feedback Iodine is used in the primary stain after spraying the slide with alcohol, the iodine acts a a mordant by helping the crystal violet stick to the cell walls of the gram positive organisms.
An alpha thalassemia patient is diagnosed as having three of their four genes deleted which code for alpha hemoglobin chains. What type of hemoglobin is abnormal and would be found in such a patient?
Hb H Feedback Hemoglobin H is composed of tetrad of beta-globin chains instead of the usual 2 alpha and 2 beta-globin chains.
An electrophoretic separation of lactate dehydrogenase isoenzyme that demonstrates elevation in LD-1 greater than LD-2 could be indicative of:
Hemolysis -Hemolysis causes an elevation of LD-1 and LD-2, also both are increased during myocardial infarction since they are both present in the heart muscle. -Normally LD-2>LD-1 and the reverse is true in myocardial infarction and during states of hemolysis.
All of the following diseases are associated with autoantibodies, EXCEPT? a. Wegner's Disease b. Rheumatoid arthritis c. Systemic lupus erythematosus d. Hemolytic disease of the Newborn
Hemolytic disease of the Newborn (HDN) Feedback HDN is a condition related to alloantibodies from the mother's bloodstream directed against the baby's red cell antigens.
Barr body
Identify the neutrophil nuclear projection in this image.
The antibody mediatory associated with Type 1 hypersensitivity Reaction is:
IgE Feedback The mas cells carries receptors for the Fc portion of IgE. The IgE occupying the receptors, induce a mast cell de-granulation immediately after allergens are encountered.
Blood culture bottles utilized in continuous monitoring systems, such as the BacTec, use resins or charcoal to do what?
Inactivate and absorb out antimicrobial agents Feedback Inactivate and absorb out antimicrobial agents is the correct answer because resins and charcoal are able to absorb out and inactivate antimicrobial agents, which will enhance the recovery of microorganisms.
When a patient is suspected of intoxication, what would you expect the osmol gap to be?
Increased Feedback -The osmol gap (the difference in measured vs calculated osmolality) would be increased in patient suspected of intoxication. -Including ethanol, isopropanol, methanol, and ethylene glycol. -Due to the increase in unmeasured substances (alcohols), the gap between the measured and calculated will be larger; and so, the gap will not be normal or decreased.
The glucose result on a urine specimen from an infant is negative on the urine chemical reagent strip, what is the next step?
It must be followed by the copper reduction test (Clinitest) to check for other reducing substances. Feedback -Clinitest is used as a secondary confirmation test to check for other reducing substances. -Clinitest is a tablet that is based on the classic Benedict's copper reduction reaction. *Keep in mind, not an Acetest, an Acetest is used as a confirmatory test for ketones and can be used to test urine, serum, and whole blood.
The immunoglobulin molecule is made up of both heavy and light chains- the light chains can be compromised of which of the following?
Kappa or lambda Feedback Kappa and lambda chains make up the light chains of an immunoglobulin molecule.
In a urinalysis, tests are performed that serve as a method of screening for urinary tract infections. Which of the following tests detects the presence of inflammatory cells?
Leukocyte esterase test Feedback Leukocyte esterase test is the correct answer because this test detects inflammation, which indicates the presence of polymorphonuclear cells. These cells have granules that have leukocyte esterase activity. However, this test is not sensitive enough for determining pyuria in patients with the acute urethral syndrome.
What is the primary target of HBV?
Liver Feedback The liver is the primary target organ for the Hepatits B virus (HBV). The inflammation caused by HBV can result in permanent liver damage, including cirrhosis, liver failure, and hepatocellular carcinoma.
Pericarditis may occur as a complication from endocarditis caused by Staphylococcus aureus. Virulence mechanisms attributed to the spread of this organism include all of the following EXCEPT: a. Hyaluronidase b. Protein A c. Coagulase d. M protein
M protein Feedback M protein is a virulence factor of streptococcus pygoenes, which increases resistance to phagocytosis and faciliates attachment t omucosal cells.
What condition would you expect to find Howell-Jolly bodies?
Megaloblastic anemia Feedback -Howell-Jolly bodies are associated with megaloblastic anemia. They are observed on a Wright-stained peripheral blood smear from a patient who has a hypo-functioning spleen or has had their spleen removed. *Keep in mind splenomegaly does not result in increased Howell-Jolly bodies. The spleen would remove them.
What is the earliest biochemical marker of myocardial infarction?
Myoglobin Feedback In a myocardial infarction, myoglobin is elevated when muscle tissue is damaged (in this case heart muscle) but it lacks specificity. But in this case, since heart muscle is being damaged, it responds very rapidly after a myocardial infarction and rises within 1-3 hours and it returns to normal within 24 hours.
This foot infection, as illustrated in the upper photograph, was the result of a farmer walking barefoot in soil contaminated with filariform larvae. Based on the morphology of the 50 µm ovum (lower image), select the organism that is the probable cause of this infection.
Necator americanus Feedback -Necator americanus -Humans become infected by direct penetration of hookworm filariform larvae into hair follicles, pores, or skin (upper image) that have come in direct contact with contaminated -The 50 µm in diameter ovum as illustrated in the lower photomicrograph has a smooth, thin smooth shell and internal yolk sacks that leave a clear space.
When thinking about anticonvulsant medications, what medication does not rely solely on the liver to metabolize it for excretion?
Phenobarbital Feedback -The Liver hepatocytes mostly metabolize phenobarbital. However the kidney also has significant filtration; both liver and kidney function should be monitored during treatment to reduce toxicity.
Glitter cell is a term used to describe a specific type of:
Neutrophil Feedback -Neutrophils are predominant WBC found in urine sediment. -They exposed to hypotonic urine absorb water and swell, and the granules exhibit Brownian motion resulting in a sparkling appearance referred to as glitter cells.
Phagocytosis by cells of the mononuclear phagocytic system is greatly enhanced by what?
Opsonins Feedback Opsonins bind to antigens and then increase the rate of action which phagocytes destroy invading microorganisms or particles. This is called opsonization.
What might cause a false positive indirect antiglobulin test (IAT)?
Over-centrifugation Feedback The correct answer is over-centrifugation. Over-centrifugation may cause either a false positive result, (if centrifuged clumps cannot be completely dispersed) or a false negative result (if too much agitation is required for resuspension).
Upon centrifugation, a cerebrospinal fluid (CSF) sample supernatant exhibited xanthochromia. The image is a Wright-Giemsa stained smear that was made from that CSF sample. What condition is probably related to these macroscopic and microscopic findings?
Previous subarachnoid hemorrhage Feedback Xanthochromia may be an indication of previous subarachnoid hemorrhage (SAH). The presence of dark, granular, iron-laden hemosiderin deposits, indicated by the blue arrows, and yellow, crystalline, iron-free hemotoidin crystals (red arrows) in macrophages, point to an SAH several hours to days prior to CSF analysis. Macrophages begin to appear in CSF approximately two hours after bleeding occurs into the central nervous system. The macrophages start to phagocytize red blood cells (RBCs). As the RBCs degenerate further, the breakdown products are seen in the phagocytic cells as hemosiderin deposits or hematoidin crystals. The appearance of hemosiderin and hematoidin crystals occurs approximately 18 hours following an SAH and may be present in the CSF for several months.
A technologist is evaluating a blood smear. The technologist notices variability in cell size. What parameter from the automated complete blood count would confirm the anisocytosis observed on the blood smear?
RDW (Coefficient of variation of the MCV or variability in sizes of the erythrocytes. Elevation of the RDW will be indicative of anisocytosis. Feedback -Anisocytosis is the medical term for having RBCs that are unequal in size. -Anisocytosis is usually caused by anemia.
When performing an antibody screen, both the screen cells are 4+ at immediate spin and W+ at AHG. The antibody panel shows 4+ reactions at immediate spin and w+ reactions at AHG and there is no specific match to the reaction pattern. That auto-control is negative. What would be the logical next step?
Repeat testing using warmed patient sample or reagent and just do AHG reading Feedback This is strong cold antibody which is still present after incubation and washing, warming the samples or reagents and eliminating this phase will prevent the antibody from binding.
Which one of the following statements about lead poisoning is false? a. While lead distributes to all tissues, the central nervous system, kidney, and bone marrow are particularly susceptible to lead toxicity. b. Whole blood lead measurements is the best test for detecting lead toxicity. c. Serum lead level is good inexpensive screening test for lead toxicity. d. Lead levels below 5 ug/dL in children do no prompt ongoing monitoring.
Serum lead level is good inexpensive screening test for lead toxicity. Feedback Lead is a metal commonly found in the environment which can be very toxic. The use of lead varies widely in our society and until the 1970s not much attention was given to its toxicity, especially on the growth and development in children.
What test is used to confirm a syphilis infection after another method tests positive for syphilis?
T. pallidum particle agglutination (TP-PA) test -TA-PA is a test used to confirm a previous positive method for syphilis.
What is the most common cause of hyperkalemia in hospitalized patients?
Therapeutic potassium replacement Feedback -Hyperkalemia is a condition with higher than normal levels of potassium in the serum. The most common cause in "hospitalized patients" is due to therapeutic potassium replacement. *Keep in mind hyperkalemia also occurs in cellular injury, chemotherapy, and leukemia through a cellular shift.
The image is a stained smear of cerebrospinal fluid. What can be said about this image?
They line the arachnoid space. -These are ependymal cells which are found in the tissues lining the ventricles, neural canal, and the arachnoid space.#
Following lipid rests would be expected to the FALSELY elevated on a serum specimen from a non-fasting patient?
Triglyceride Feedback Triglyceride blood concentrations change significantly when you eat, and when you eat a meal that contains a lot of fat, your triglyceride levels rise, which is why it's very important to fast before getting a sample.
Following the treatment of an IgG molecule with papain, what will remain?
Two Fab fragments each with a light chain and a partial heavy chain attached with a disulfide bond Feedback -Digestion with papin will cut the disulfide bond that holds the heavy chains together, leaving the two units, each with a partial heavy chain and a light chain held together with a disulfide bond.
A deficiency in what vitamins is associated with "Night Blindness"?
Vitamin A Feedback Vitamin A deficiency can cause night blindness.
Approximately how many out of 1,000,000 Caucasians will have the following phenotype?Group 0, K+, Jk(a+)
30,000 Feedback -Group O blood types comprise about 45% of the Caucasian population. Out of 1,000,000 people, this leaves us with about 450,000 people. -Approximately 9% of Caucasians have the K antigen, leaving us with 40,500 individuals who are group O, K+. -Approximately 77% of Caucasians are positive for the Jka antigen. 77% of 40,500 individuals leaves us with 31,185 or approximately 30,000 individuals that are group O, K+ and Jk(a+).
What is MOST often determined to be the cause of sepsis?
Bacteria Feedback -Bacteria is the most common cause, along with fungal organisms, viruses, and parasites. -Infection by any microorganism could potentially result in sepsis if the immune system overreacts to the invader. However, bacterial organisms account for the majority of sepsis cases.
Which microorganisms is LEAST likely to produce a capsule or slime layer? a. E. Coli b. Klebsiella pneumoniae c. Streptococcus pneumoniae d. Pseudomonas aeruginosa
E. Coli Feedback Escherichia coli is the correct answer because out of all the organisms listed, this organism is least likely to produce a capsule or slime layer.
A quality control program is to be set up for the following tests: Phenylalanine deaminase (PAD) Indole production Voges-Proskauer (V-P) What pair of stock culture organisms would be most suitable to verify the performance of these three tests?
Klebsiella pneumoniae, P. Vulgaris
A variety of additives are used in blood collection tubes. Which of the follwoing additives inhibits glycolysis?
Sodium fluoride Feedback Sodium fluoride is the gray top tube and it is used to inhibit glycolysis (or stop the metabolism of glucose) to determine the correct glucose levels.
The positive square root of the variance of a set of values is called:
Standard deviation Feedback The standard deviation measures the spread of the data about the mean value. It is useful in comparing sets of data that may have the same mean but a different range. The standard deviation is calculated by taking the positive square root of the variance of a set of values.
A thoracentesis specimen was collected and sent to the laboratory for testing. What body area was this specimen collected?
Thorax Feedback Thorax is the correct answer because a thoracentesis is a procedure where a needle is placed through the chest wall into the pleural space (lining between the chest wall and lungs). The fluid collected will be sent to the laboratory for testing, such as cell count, total protein, glucose, and culture. Fluid collected from the thorax can also be called thoracentesis, pleural, or empyema fluid.
Compared to plasma frozen within 8 hours of collection, plasma frozen within 24 hours of collection will likely have reduced levels of Factor:
VIII Feedback Plasma that is frozen within 24 hours of collection, often abbreviated as PF24 or FP24, contains the same clotting factors as plasma frozen within 8 hours of collection, but it often contains reduced levels of Factor V and Factor VIII.
The fastidious Gram-negative bacillus featured here has been recovered from individuals in pandemic outbreaks of diarrhea after ingestion of contaminated stream, lake, or well water. In many cases, life-threatening profuse diarrhea resulting in dehydration and electrolyte loss is experienced. Smooth, entire, convex light gray-yellow colonies are observed on blood agar (left upper image). Note the yellow pigmentation of the colonies growing on TCBS agar (Thiosulfate Citrate Bile Sucrose) on the right of the composite image, indicating strong acid production from sucrose. Cytochrome oxidase is also positive. Small, curved, and S-shaped, gram-negative bacilli are seen on the Gram stain. From these observations, select the correct genus/species identification of this isolate.
Vibrio Cholerae Feedback Vibrio cholerae -Growth: smooth, entire, light gray-yellow colonies on blood agar -Curved gram-negative bacilli -Positive biochemical reactions: cytochrome oxidase, catalase, indole, lysine, ornithine decarboxylase, and fermentation of sucrose. -Negative: Esculin -Additional info: beta-hemolytic on blood agar, Voges Proskauer positive, and resistant to Polymyxin B.
The laboratorian completed the mixing study ordered for John Doe. The results are as follows: Initial aPTT result: 167 seconds Initial 1:1 Mix with Normal Pooled Plasma: 158 seconds Incubated 1:1 Mix with Normal Pooled Plasma: 150 seconds Which of the choices below would most likely explain the results for this patient?
immediate-acting coagulation inhibitor Feedback This patient is most likely suffering from an immediate-acting coagulation inhibitor; most commonly, lupus anticoagulant.