NBDHE NBDHE Scientific Basis of Practice 4 — Questions and Answers
Question 1: A patient presents with painless, soft-tissue swelling of the submandibular gland that enlarges during meals. Which condition is most likely?
- Mucocele
- Sialolithiasis (Correct answer)
- Pleomorphic adenoma
- Necrotizing sialometaplasia
Correct answer: Sialolithiasis
Sialolithiasis (salivary duct stones) causes obstruction and swelling during salivary stimulation by meals, most commonly affecting the submandibular gland.
Question 2: Which cell is the primary effector of the innate immune response and is the first to arrive at a site of acute bacterial infection?
- Macrophage
- Natural killer cell
- Neutrophil (Correct answer)
- Dendritic cell
Correct answer: Neutrophil
Neutrophils (PMNs) are the first cells recruited to sites of acute infection, where they phagocytose bacteria and release antimicrobial substances.
Question 3: Which drug class is the first-line pharmacologic treatment for a patient experiencing acute anaphylaxis?
- Corticosteroids
- Antihistamines (H1 blockers)
- Epinephrine (Correct answer)
- Beta-2 agonists
Correct answer: Epinephrine
Intramuscular epinephrine is the first-line treatment for anaphylaxis because it reverses bronchospasm, vasodilation, and angioedema through adrenergic receptor activation.
Question 4: What is the term for the process by which bacteria transfer genetic material via bacteriophages, enabling antibiotic resistance transfer?
- Transformation
- Conjugation
- Transduction (Correct answer)
- Translation
Correct answer: Transduction
Transduction is the transfer of bacterial DNA mediated by bacteriophages (viruses that infect bacteria), enabling horizontal gene transfer of resistance genes.
Question 5: Which type of bone cell is responsible for the resorption of mineralized bone matrix?
- Osteoblast
- Osteocyte
- Osteoclast (Correct answer)
- Cementoblast
Correct answer: Osteoclast
Osteoclasts are multinucleated cells derived from monocyte precursors that resorb bone by secreting acid and lysosomal enzymes into the resorption lacuna.
Question 6: A patient has xerostomia and reduced salivary flow. Which buffer system in saliva is most important for neutralizing plaque acids?
- Protein buffer system
- Phosphate buffer system
- Bicarbonate buffer system (Correct answer)
- Citrate buffer system
Correct answer: Bicarbonate buffer system
The bicarbonate buffer system is the dominant buffer in stimulated saliva, neutralizing plaque acids generated by cariogenic bacteria.
Question 7: Which phase of the cell cycle is characterized by DNA synthesis and chromosome replication?
- G1 phase
- S phase (Correct answer)
- G2 phase
- M phase
Correct answer: S phase
DNA synthesis and replication of chromosomes occur during the S (synthesis) phase of the cell cycle, between G1 and G2.
NBDHE NBDHE Scientific Basis of Practice 4
A patient presents with painless, soft-tissue swelling of the submandibular gland that enlarges during meals.
Which condition is most likely?