Med Lab Science Review #23: Protozoa, PCR, & Lab Practices

MEDICAL LABORATORY SCIENCE 9. SUMMATIVE EXAM REVIEW QUESTIONS #23 + ANSWERS & RATIONALIZATIONS 1. 2. 3. 4. 5. 6. 7. 8. East African sleeping sickness: The two primary species of fly vectors responsible for transmitting are Glossina morsitans and Glossina pallidipes: a. Leishmania donovani b. Leishmania tropica c. Trypanosoma brucei gambiense d. Trypanosoma brucei rhodesiense One of the following protozoan organisms has been implicated in waterborne and foodborne outbreaks. The suspect organism is: a. Pentatrichomonas hominis b. Dientamoeba fragilis c. Giardia lamblia → Traveler’s diarrhea d. Balantidium coli Organisms that should be considered in a waterborne outbreak of diarrheal disease include: a. Giardia lamblia and Cryptosporidium spp. b. Endolimax nana and Entamoeba histolytica c. Blastocystis hominis and Trichomonas vaginalis d. Toxoplasma gondii and Schistosoma mansoni For most histochemical and histological techniques, it is necessary to bring the pH of any formalin solution used to neutral because: a. Acidic formalin solutions swell tissues b. Formic acid is formed in formaldehyde solutions c. Acidic formalin removes lipids from the tissue d. Basic formalin solutions tend to polymerize Which species of Plasmodium may readily be identified when crescent-shaped gametocytes are found in stained blood films? a. P. falciparum b. P. malariae c. P. ovale d. P. vivax Reddish brown, dorsoventrally flattened, wingless insects that attack most any mammal, feeding primarily at night; during daylight hours, they hide under mattresses, loose wallpaper, and floorboards: a. Bed bugs b. Fleas c. Mites d. Ticks Cause of inflammation and itchiness of bed bug bites: a. Antenna b. Saliva c. Wings d. Any of these The enzyme ligase joins the Okazaki fragments of the: a. Template strand b. Lagging strand c. Leading strand d. Primer fragments → Okazaki fragments are short sections of DNA formed at the time of discontinuous synthesis of the lagging strand during replication of DNA. 10. 11. 12. 13. 14. 15. Identify the correct sequence of events for a polymerase chain reaction (PCR) cycle. a. Anneal, extend, and denature b. Denature, anneal, and extend c. Extend, anneal, and denature d. Extend, denature, and anneal → PCR Components ▪ Template DNA - Includes target sequence Target DNA must be denatured to SingleStranded DNA before it can serve as a template for PCR ▪ Oligonucleotide Primers - Short segments of DNA that are between 20 and 30 nucleotides long, that are complimentary to opposite strands that flank the sequence of interest to be amplified and detected ▪ Magnesium chloride - Enzyme cofactor ▪ Deoxynucleotides of each base (dNTP) Nucleotides being added (A, G, T, C) ▪ Polymerase (Thermus aquaticus, thus “Taq” polymerase) - Allows for addition of dNTPs at 50 end during extension Which enzyme catalyzes DNA replication? a. Endonuclease b. Ligase c. Polymerase d. Reverse transcriptase What is the unique characteristic of the DNA polymerase, Taq DNA polymerase, used in PCR? a. It can be enzyme labeled b. It is more efficient than eukaryotic polymerases c. It is heat stable d. It works with DNA of any species In the PCR cycle, how is denaturation accomplished? a. Heat → 94°C b. Alkali treatment c. Addition of sulfonylurea d. Formamide In the PCR, a ______ initiates extension of the sequence of interest by allowing Taq polymerase to begin adding nucleotides to single-stranded DNA. a. Probe b. Ligase c. Promoter d. Primer What is the composition of the primer used in PCR? a. A cocktail of enzymes and nucleotide triphosphates that bind to the target b. An oligonucleotide complementary to bases at the 3 ́ end of the target c. A small piece of dsDNA that attaches to the template d. A probe made of mRNA that binds downstream from the target The master mix solution used for PCR contains: which of the following reagents? a. Deoxyribonucleotide triphosphates b. Deoxyribonucleotide monophosphates c. Deoxyribonucleosides d. Ribonucleotide monophosphates 1 16. In PCR testing, the initial step involves adding the DNA in question to a mixture of Taq polymerase, excess nucleotides, MgCl2, and primers. This mixture is placed in which of the following instruments to allow the amplification to take place? a. Flow cytometer b. Capillary array sequencer c. Thermal cycler d. Electrophoresis chamber → The PCR reactions uses a Thermocycler, which allows for the rapid change in temperature needed for each step. 17. How can PCR be applied to the detection of human immunodeficiency and other RNA viruses? a. The virus must be inserted into human DNA by viral integrase prior to PCR b. Substitute deoxyuridine triphosphate in place of deoxythymidine triphosphate in the master mix c. Add a heat-stable reverse transcriptase enzyme to the master mix d. Substitute ribonucleotide triphosphates for deoxyribonucleotide triphosphates in the master mix 18. PCR involving the sequential use of two primer sets: a. Multiplex PCR b. Nested PCR c. Arbitrary primed PCR d. RT-PCR 19. Monitoring the load of HIV circulating in a patient’s plasma would be best accomplished using which method? a. ELISA b. DNA sequencing c. Northern blot d. Real-time nucleic acid amplification 20. Isothermal amplification: Loop-mediated isothermal amplification (LAMP) uses ___ primers and proceeds using a constant temperature coupled to a strand displacement reaction. a. 2 primers b. 3 primers c. 4 primers d. 5 primers 21. Signal amplification differs from target amplification when designing protocols for identification of nucleic acids. Which of the following is an example of a signal amplification technique? a. Branched-chain DNA detection b. Ligase chain reaction c. Polymerase chain reaction d. Reverse-transcriptase PCR 22. The detection of the DNA from cytomegalovirus (CMV) and human papillomavirus (HPV) is typically performed using the Hybrid Capture assay. What type of assay is Hybrid Capture? a. Target amplification assay b. Signal amplification assay c. Reverse transcriptase assay d. Viral load assay 23. The technique that uses fluorescent DNA probes to detect chromosomal abnormalities within cells in cytogenetic studies is referred to as: a. Fluorescence in situ hybridization (FISH) b. Karyotype in situ hybridization (KISH) c. Fluorescence in situ PCR d. Microarray 24. Preanalytical (preexamination) variables in laboratory testing include: a. Result accuracy b. Report delivery to the ordering physician c. Test turnaround time d. Specimen acceptability 25. A preanalytical error can be introduced by: a. Drawing a coagulation tube before an EDTA tube b. Mixing an EDTA tube 8-10 times c. Transporting the specimen in a biohazard bag d. Vigorously shaking of blood tube to prevent clotting 26. Which of the following is not a potential source of postanalytical (postexamination) errors? a. Excessive delay in reporting or retrieving a test result b. Interpretation of result c. Verbal notification of test result d. Labeling the specimen at the nurses' station 27. The most important diagnosis and therapeutic management decision tool used to interpret test results is: a. Statistical analysis b. Reference intervals c. Specimen acceptability d. The age of a patient 28. Delta check is a method that: a. Determines the mean and variance of the instrument b. Monitors the testing system for precision c. Monitors patient samples day to day d. Is determined in each laboratory facility 29. A new reference interval is established when there is no existing analyte or methodology in the clinical or reference laboratory with which to conduct comparative studies. It is a costly and labor-intensive study that will involve laboratory resources at all levels and may require from ___ to as many as ≈700 study individuals. → establishing a reference interval a. 20 study individuals b. 50 study individuals c. 100 study individuals d. 120 study individuals 30. This is done to confirm the validity of an existing reference interval for an analyte using the same (identical) type of analytic system (method and/or instrument). These are the most common reference interval studies performed in the clinical laboratory and can require as few as ___ study individuals. a. 20 study individuals b. 50 study individuals c. 100 study individuals d. 120 study individuals → Transference - verifying a reference interval 2 31. What does the preparation of a Levey-Jennings quality control chart for any single constituent of serum require? a. Analysis of control serum over a period of 20 consecutive days b. 20 to 30 analyses of the control serum on 1 day, in one batch c. Analyses consistently performed by one person d. Weekly analyses of the control serum for 1 month → Analyses of aliquots of the pools are done in duplicate over a period of 20 days, preferably by all workers who will subsequently be using the controls. → Acceptable range is assigned is usually the mean ±2 SD 32. The acceptable limit of error in the chemistry laboratory is 2 standard deviations. If you run the normal control 100 times, how many of the values would be out of the control range due to random error? a. 1 b. 5 c. 10 d. 20 33. Which of the following describes the ability of an analytical method to maintain both accuracy and precision over an extended period of time? a. Reliability b. Validity c. Probability d. Sensitivity 34. Amount of light absorbed by a solution is ______ proportional to the concentration of the solution. a. Directly b. Inversely c. Variable d. Cannot be determined 35. Logarithm of the transmitted light is ______ proportional to its concentration. a. Directly b. Inversely c. Variable d. Cannot be determined 36. In the visible light spectrum, the color red is in what nanometer range? a. 380-440 nm b. 500-580 nm c. 600-620 nm d. 620-750 nm 37. Osmometry is a technique for measuring the concentration of solute particles that contribute to the osmotic pressure of a solution. The most common method used in a clinical laboratory to measure osmolality is: a. Dew point pressure b. Boiling point c. Freezing point depression d. Osmotic pressure 38. One of the major hormones that controls high glucose levels after a meal is: a. Insulin b. Thyroxine c. Glucagon d. Lipase 39. In a person with normal glucose metabolism, the blood glucose level usually increases rapidly after carbohydrates are ingested but returns to a normal level after: a. 30 minutes b. 45 minutes c. 60 minutes d. 120 minutes 40. Which of the following organs uses glucose from digested carbohydrates and stores it as glycogen for later use as a source of immediate energy by the muscles? a. Kidneys b. Liver c. Pancreas d. Thyroid 41. Which of the following electrolytes is the chief cation in the plasma, is found in the highest concentration in the extravascular fluid, and has the main function of maintaining osmotic pressure? a. Potassium b. Sodium c. Calcium d. Magnesium 42. Ninety percent of the carbon dioxide present in the blood is in the form of: a. Bicarbonate ions b. Carbonate c. Dissolved CO2 d. Carbonic acid 43. Creatinine clearance is used to assess the: a. Glomerular filtration capabilities of the kidneys b. Tubular secretion of creatinine c. Dietary intake of protein d. Glomerular and tubular mass 44. Expected creatinine clearance for a patient with chronic renal disease would be: a. Very low; renal glomerular filtration is functioning normally b. Normal; renal glomerular filtration is functioning normally c. Very high; renal glomerular filtration is not functioning normally d. Very low; renal glomerular filtration is not functioning normally 45. Blood is collected from a patient who has been fasting since midnight; the collection time is 7 am. Which of the following tests would not give a valid test result? a. Cholesterol b. Triglycerides c. Total bilirubin d. Potassium 46. In what major organ of the body is the majority of the body’s cholesterol synthesized? a. Heart b. Pancreas c. Gallbladder d. Liver 3 47. Which of the following laboratory values is considered a positive risk factor for the occurrence of coronary heart disease? a. HDL cholesterol >60 mg/dL b. HDL cholesterol <35 mg/dL c. LDL cholesterol <30 mg/dL d. Total cholesterol <200 mg/dL 48. The National Cholesterol Education Program (NCEP) has established cutoffs for total cholesterol and LDL cholesterol to define persons at high risk for coronary heart disease later in life. What is the cutoff for a desirable LDL cholesterol concentration? a. <130 mg/dL b. <160 mg/dL c. <200 mg/dL d. >130 mg/dL 49. Skeletal muscle markers: a. CK-MM b. CK-MM, AST c. CK-MM, AST, Aldolase d. CK-MM, AST, Aldolase, LD-4 and LD-5 50. Increased ADH: a. Fluid loss, low serum sodium b. Fluid loss, high serum sodium c. Fluid retention, low serum sodium d. Fluid retention, high serum sodium → Hormones related to fluids and sodium ▪ Increased ADH = Fluid retention, low serum Na+ ▪ Decreased ADH = Fluid loss, high serum Na+ ▪ Increased Aldosterone = Hypertension, low serum K+ ▪ Decreased Aldosterone = Low serum Na+, high serum K+ ▪ Increased Renin = Hypertension 4