Free National Board Exam Sciences Practice Questions

Sample Practice Questions

Try these 10 sample questions from the National Board Exam Sciences practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1An embalmer's airborne formaldehyde exposure is sampled across an entire 8-hour work shift in the preparation room. Under the OSHA formaldehyde standard, what is the highest 8-hour time-weighted average concentration the embalmer may be exposed to?

   1. A. 0.75 parts formaldehyde per million parts of air
   2. B. 0.50 parts formaldehyde per million parts of air
   3. C. 2.0 parts formaldehyde per million parts of air
   4. D. 0.10 parts formaldehyde per million parts of air

   Answer: A

   Explanation: 29 CFR 1910.1048(c)(1) sets the 8-hour limit: "TWA: The employer shall assure that no employee is exposed to an airborne concentration of formaldehyde which exceeds 0.75 parts formaldehyde per million parts of air (0.75 ppm) as an 8-hour TWA." The other three values are real thresholds in the same standard but govern something else: 0.5 ppm is the action level, 2 ppm is the 15-minute short-term exposure limit, and 0.1 ppm is the airborne concentration below which the standard says symptoms of overexposure occur only in exceptional circumstances.

   Reference: Code of Federal Regulations, Title 29 — 29 CFR 1910.1048(c)(1)

2. 2Restorative work on the head requires knowing how the bones of the skull are grouped. Into which two regions is the skull divided, and what does each contain?

   1. A. The neurocranium, which protects the brain, and the viscerocranium, which forms the face
   2. B. The neurocranium, which forms the face, and the viscerocranium, which protects the brain
   3. C. The calvarium, which protects the brain, and the splanchnocranium, which forms the cranial base
   4. D. The cranial vault, which protects the brain, and the cranial fossae, which form the face

   Answer: A

   Explanation: The article divides the skull into "the neurocranium (which protects the brain) and the viscerocranium (which forms the face)," and states that "The skull consists of 22 bones in most adult specimens, which come together via cranial sutures." Option B swaps the two definitions. The calvarium and the cranial fossae named in the other options are real parts of the skull, but they are subdivisions of the neurocranium rather than the two-part scheme the article uses.

   Reference: Anatomy, Head and Neck, Skull - StatPearls - NCBI Bookshelf — StatPearls, Anatomy, Head and Neck, Skull, 'Introduction' and 'Structure and Function'

3. 3A funeral home will receive unembalmed remains arriving from abroad for burial. Under the federal quarantine regulation on importation of human remains, to whom must those remains be consigned?

   1. A. Directly to a licensed mortuary, cemetery, or crematory for immediate and final preparation
   2. B. Directly to the port health office for inspection before release to a licensed mortuary
   3. C. Directly to an entity authorized to perform medical examination or autopsy in that jurisdiction
   4. D. Directly to the state registrar of vital records for verification of the death certificate

   Answer: A

   Explanation: 42 CFR 71.55(c)(1) provides that human remains imported for burial, entombment, or cremation must "Be consigned directly to a licensed mortuary, cemetery, or crematory for immediate and final preparation prior to burial, entombment, or cremation." Option C states the real consignee, but the next paragraph of the same rule assigns it to a different purpose: remains imported "for medical examination or autopsy" must go to an entity authorized to perform those functions.

   Reference: Code of Federal Regulations, Title 42 — 42 CFR 71.55(c)(1)(i)

4. 4The Gram stain separates bacteria into two groups by a structural difference in the cell envelope. What causes a gram-positive organism to retain the crystal violet dye?

   1. A. Its thick peptidoglycan cell wall
   2. B. Its outer lipid bilayer membrane
   3. C. Its capsule of polysaccharide material
   4. D. Its content of wall teichoic acids

   Answer: A

   Explanation: The article states: "The staining method uses crystal violet dye, which is retained by the thick peptidoglycan cell wall of gram-positive organisms." It contrasts this with gram-negative bacteria, which "classically have an outer membrane" and "a thinner peptidoglycan layer that does not retain the blue dye used in the initial dyeing process." Every distractor names a real bacterial envelope structure that simply does not govern dye retention: the outer lipid bilayer belongs to the group that fails to retain the stain, while polysaccharide capsules and wall teichoic acids are genuine constituents found on organisms of either staining class.

   Reference: Gram-Positive Bacteria - StatPearls - NCBI Bookshelf — StatPearls, Gram-Positive Bacteria, 'Introduction'

5. 5While pouring concentrated arterial fluid into a mixing container, an embalmer generates a brief, intense release of formaldehyde vapor lasting several minutes. Which exposure limit in the OSHA formaldehyde standard governs this kind of brief peak, and what is its value?

   1. A. The short-term exposure limit, 2 ppm measured as a 15-minute average
   2. B. The short-term exposure limit, 2 ppm measured as a 30-minute average
   3. C. The short-term exposure limit, 0.75 ppm measured as a 15-minute average
   4. D. The short-term exposure limit, 0.5 ppm measured as a 15-minute average

   Answer: A

   Explanation: 29 CFR 1910.1048(c)(2) provides: "Short Term Exposure Limit (STEL): The employer shall assure that no employee is exposed to an airborne concentration of formaldehyde which exceeds two parts formaldehyde per million parts of air (2 ppm) as a 15-minute STEL." Both the concentration and the averaging period are fixed by the rule. The distractors substitute a real averaging period from other OSHA substance standards, or substitute the 8-hour TWA value (0.75 ppm) and the action level (0.5 ppm), each of which is measured over 8 hours rather than 15 minutes.

   Reference: Code of Federal Regulations, Title 29 — 29 CFR 1910.1048(c)(2)

6. 6How many facial bones make up the viscerocranium, and how many bones does the adult skull contain in total?

   1. A. 14 facial bones out of 22 skull bones
   2. B. 12 facial bones out of 22 skull bones
   3. C. 14 facial bones out of 28 skull bones
   4. D. 8 facial bones out of 22 skull bones

   Answer: A

   Explanation: The article states that "The skull consists of 22 bones in most adult specimens" and that "There are 14 facial bones with specific anatomical landmarks and embryologic development mechanisms." It enumerates them: "These include the two nasal conchae, two nasal bones, two maxilla bones, two palatine bones, two lacrimal bones, two zygomatic bones, the mandible, and the vomer." The figure 8 in option D is the number of bones conventionally counted in the neurocranium, the complement of the 14.

   Reference: Anatomy, Head and Neck, Skull - StatPearls - NCBI Bookshelf — StatPearls, Anatomy, Head and Neck, Skull, 'Structure and Function'

7. 7Unembalmed remains are being imported for burial and the accompanying death certificate is missing. Under the federal quarantine regulation, what must accompany the remains instead?

   1. A. An importer certification statement confirming that the remains are not known to contain, or stating why they are not reasonably suspected of containing, an infectious biological agent
   2. B. An importer certification statement confirming that the remains have been disinfected in accordance with the practices of the country of origin
   3. C. A consular mortuary certificate issued by the United States mission in the country where the death occurred
   4. D. A permit issued by the Director under the regulation governing importation of etiological agents

   Answer: A

   Explanation: 42 CFR 71.55(c)(1)(ii) requires that remains for burial, "Unless embalmed, be accompanied by a death certificate or, if the death certificate is incomplete or missing, an importer certification statement confirming that the human remains are not known to contain or stating why the human remains are not reasonably suspected of containing an infectious biological agent." The permit in option D is real but it belongs to a different route, since the same rule applies only to remains "Unless accompanied by a permit issued under 42 CFR 71.54."

   Reference: Code of Federal Regulations, Title 42 — 42 CFR 71.55(c) and (c)(1)(ii)

8. 8How thick is the peptidoglycan layer of a gram-positive cell wall compared with that of a gram-negative one?

   1. A. 20 to 80 nm in gram-positive organisms, against 2 to 3 nm in gram-negative organisms
   2. B. 2 to 3 nm in gram-positive organisms, against 20 to 80 nm in gram-negative organisms
   3. C. 20 to 80 nm in gram-positive organisms, against 10 to 15 nm in gram-negative organisms
   4. D. 80 to 200 nm in gram-positive organisms, against 2 to 3 nm in gram-negative organisms

   Answer: A

   Explanation: The article states: "It is a 20 to 80 nm-thick polymer, whereas the peptidoglycan layer of the gram-negative cell wall is 2-3 nm thick and covered by an outer lipid bilayer membrane." The roughly tenfold difference is what makes the Gram stain work. Option B reverses the two values, which is the usual confusion, and the other options alter one figure while leaving the correct relationship intact.

   Reference: Gram-Positive Bacteria - StatPearls - NCBI Bookshelf — StatPearls, Gram-Positive Bacteria, 'Pathophysiology'

9. 9The OSHA formaldehyde standard uses the term "action level" as the trigger for several ongoing obligations toward an exposed embalmer. How is the action level defined?

   1. A. 0.5 ppm calculated as an 8-hour time-weighted average
   2. B. 0.5 ppm measured as a 15-minute short-term average
   3. C. 0.75 ppm calculated as an 8-hour time-weighted average
   4. D. 1.0 ppm calculated as an 8-hour time-weighted average

   Answer: A

   Explanation: The definitions paragraph of the standard states: "Action level means a concentration of 0.5 part formaldehyde per million parts of air (0.5 ppm) calculated as an eight (8)-hour time-weighted average (TWA) concentration." Both halves matter: the action level is half the permissible exposure limit and it is an 8-hour average, not a short-term average. Option C is the permissible exposure limit itself rather than the action level.

   Reference: Code of Federal Regulations, Title 29 — 29 CFR 1910.1048(b), definition of "action level"

10. 10A restorative artist rebuilding the bridge of the nose needs to identify the paired facial bone lying immediately medial to the orbit and below the frontal bone. Which of the following is a paired facial bone?

    1. A. The lacrimal bone
    2. B. The vomer
    3. C. The mandible
    4. D. The ethmoid bone

    Answer: A

    Explanation: The article's enumeration of the 14 facial bones is explicit about which are paired: "the two nasal conchae, two nasal bones, two maxilla bones, two palatine bones, two lacrimal bones, two zygomatic bones, the mandible, and the vomer." The lacrimal bones are among the paired ones, whereas the vomer and the mandible are the two unpaired members of the same list. The ethmoid is a real skull bone but the article assigns it to the neurocranium, noting the skull base "including the sphenoid and ethmoid bones" forms via endochondral ossification.

    Reference: Anatomy, Head and Neck, Skull - StatPearls - NCBI Bookshelf — StatPearls, Anatomy, Head and Neck, Skull, 'Structure and Function'