Answers with Rationales latest update 2025
1. Which of the following organisms is a Gram-positive coccus that forms clusters?
A. Streptococcus pyogenes
B. Escherichia coli
C. Staphylococcus aureus
D. Neisseria gonorrhoeae
Answer: C. Staphylococcus aureus
Rationale: Gram-positive cocci in clusters typically suggest
Staphylococcus species.
2. What color top tube is typically used for coagulation studies?
A. Red
B. Green
C. Lavender
D. Light Blue
,Answer: D. Light Blue
Rationale: Light blue top tubes contain sodium citrate and are used for
PT, PTT, and other coagulation studies.
3. A urine specimen with a positive nitrite and leukocyte esterase result is
indicative of:
A. Renal failure
B. Hepatitis
C. Urinary tract infection
D. Diabetes mellitus
Answer: C. Urinary tract infection
Rationale: Both findings suggest the presence of bacteria and white
blood cells.
4. Which of the following blood components is increased in polycythemia vera?
A. Platelets
B. Leukocytes
C. Hemoglobin
D. All of the above
Answer: D. All of the above
,Rationale: Polycythemia vera increases red cells, white cells, and
platelets.
5. What is the normal range for adult hematocrit?
A. 20–25%
B. 37–52%
C. 55–70%
D. 10–15%
Answer: B. 37–52%
Rationale: Normal hematocrit levels vary slightly by gender but
generally fall within this range.
6. Which hormone regulates sodium and potassium balance?
A. Cortisol
B. Aldosterone
C. Insulin
D. Calcitonin
Answer: B. Aldosterone
Rationale: Aldosterone, secreted by the adrenal cortex, promotes
sodium retention and potassium excretion.
7. Which test is used to monitor a patient on warfarin therapy?
, A. aPTT
B. Fibrinogen
C. PT/INR
D. Bleeding time
Answer: C. PT/INR
Rationale: PT/INR is used to monitor the therapeutic range of warfarin
(Coumadin).
8. What media is selective for Neisseria gonorrhoeae?
A. Blood agar
B. MacConkey agar
C. Thayer-Martin agar
D. Chocolate agar
Answer: C. Thayer-Martin agar
Rationale: This selective medium inhibits normal flora while supporting
growth of Neisseria spp.
9. A shift to the left in a WBC differential indicates:
A. Viral infection