NBME 28 Guaranateed Success
Question 1:
A 25-year-old man presents with severe abdominal pain, nausea, and vomiting. The pain radiates from
the left flank to the groin, and examination reveals tenderness in these areas. The negative stool occult
blood test and pain characteristics indicate a high likelihood of a urinary stone.
Answer:
F) Ureteral calculus ✅
Explanation: Ureteral calculus commonly results in colicky flank pain that radiates to the groin, often
accompanied by nausea. This presentation aligns with the symptoms described.
Question 2:
The question pertains to sensory information compromised by a lesion in the anterior lobe of the
cerebellum.
Answer:
D) Unconscious proprioception ✅
Explanation: The anterior lobe of the cerebellum is involved in processing unconscious proprioception.
Damage here affects balance and coordinated movement but does not impact conscious proprioception
or other sensory modalities listed in the incorrect answers.
Question 3:
The muscle required for the action of moving the forearm from a palm-down to a palm-up position
(supination) is asked.
Answer:
A) Biceps brachii ✅
Explanation: The biceps brachii muscle is primarily responsible for supination of the forearm, as well as
flexing the elbow. Other options listed do not provide the required action for supination.
,Question 4:
Following a bone marrow transplant, a patient's biopsy indicates cytomegalovirus infection. The
question seeks to identify the enzyme that ganciclovir interferes with.
Answer:
A) DNA polymerase ✅
Explanation: Ganciclovir is a guanosine analog that inhibits viral DNA polymerase, thus interfering with
viral replication. Other choices involve enzymes related to different viral or cellular functions rather than
the action of ganciclovir.
Question 5:
The question focuses on the ovarian cells responsible for aromatizing androstenedione to estradiol
during the menstrual cycle.
Answer:
A) Granulosa ✅
Explanation: Granulosa cells are responsible for the conversion of androstenedione to estradiol via the
action of aromatase during the follicular phase of the menstrual cycle. Other cell types mentioned have
different roles in ovarian function.
If you have additional questions or need further elaboration on any topic, feel free to ask!Theca interna
cells (Choice E) are cells of the follicle that are responsible for generating androstenedione from
cholesterol, after which the androstenedione is transported to the granulosa cell to be converted to
estradiol.
Educational Objective: G
6
Exam Section 1: Item 6 of 50
National Board of Medical Examiners'
Comprehensive Basic Science Self-Assessment
,6. A 14-year-old girl is brought to the physician by her parents because of a 1-month history of a rash
that appears with sun exposure. Her parents tell the physician that she has been eating little food.
Physical examination shows a pruritic rash on the exposed
areas of the body. Her serum tryptophan concentration is decreased. Urine studies show increased
excretion of amino acids, predominantly alanine, isoleucine, leucine, phenylalanine, tryptophan, and
valine. Production of which of the following vitamins is
most likely impaired in this patient?
A) Niacin
B) Vitamin B, (thiamine)
C) Vitamin B2 (riboflavin)
D) Vitamin B5 (pantothenic acid)
E) Vitamin C ✅A.
Hartnup disease is an autosomal recessive disorder involving a defect in a kidney and intestinal neutral
amino acid transporter protein. This defect leads to aminoaciduria and a decreased absorption of
neutral amino acids from the gastrointestinal tract, resulting in
deficiencies of neutral amino acids. Neutral amino acids include tryptophan, phenylalanine, glycine,
alanine, valine, isoleucine, leucine, methionine, and proline. Tryptophan is converted to niacin, so a
deficiency in tryptophan can result in niacin deficiency. Niacin
deficiency is characterized by rash, glossitis, diarrhea, and neuropsychological disturbances such as
dementia and hallucinations.
Incorrect Answers: B, C, D, and E.
Vitamin B1 (thiamine) (Choice B) is a cofactor for several enzymes in glucose metabolism and adenosine
triphosphate production, including pyruvate dehydrogenase and a-ketoglutarate dehydrogenase.
Deficiency is characterized by Wernicke encephalopathy, a
triad of confusion, ophthalmoplegia, and ataxia. Wernicke encephalopathy is theoretically reversible
with administration of high-dose thiamine; if untreated, it can progress to Korsakoff syndrome which is
characterized by dementia, confabulation, hallucinations, and
psychosis.
Vitamin B2 (riboflavin) (Choice C) deficiency is characterized by inflammation and cracking of skin
around the lips, mouth, and tongue. It is not associated with aminoaciduria or Hartnup disease.
Vitamin B5 (pantothenic acid) (Choice D) deficiency is characterized by dermatitis, enteritis, alopecia,
and adrenal insufficiency. It is not associated with aminoaciduria or Hartnup disease.
Vitamin C (Choice E) is found in fruits and vegetables and is necessary for collagen synthesis, iron
absorption, immune function, and conversion of dopamine to norepinephrine. Deficiency causes scurvy,
which is characterized
, 7
Exam Section 1: Item 7 of 50
National Board of Medical Examiners'
Comprehensive Basic Science Self-Assessment
7. Aminoglycoside antibiotics are used for their synergistic action against bacteria, in combination with
other agents. These antibiotics demonstrate in vitro synergy for several bacterial species when
combined with which of the following classes of antibiotics?
A) Fluoroquinolones
B) Macrolides
C) Penicillins
D) Rifamycins
O E) Tetracyclines ✅C.
Aminoglycosides include gentamicin, neomycin, amikacin, tobramycin, and streptomycin. Their
bactericidal function comes from the inhibition of the 30S subunit of the bacterial ribosome, which
precludes protein synthesis by causing misreading of mRNA.
Aminoglycosides work synergistically with penicillins, meaning that the combined effect of the two
classes is stronger than the effect of either class alone. The penicillin group of antibiotics includes
penicillinase-sensitive penicillins (penicillin G, ampicillin, amoxicillin),
penicillinase-resistant penicillins (oxacillin, nafcillin, dicloxacillin), and anti-pseudomonal penicillins
(ticarcillin, piperacillin). These all inhibit peptidoglycan cross-linking of the bacterial wall.
Aminoglycosides also demonstrate synergistic activity with monobactams
such as aztreonam, which also target peptidoglycan cross-linking function. However, they do require
oxygen for their uptake into the bacterial cell so are ineffective against anaerobes. Bacteria may also
develop resistance to this class of antibiotics due to the
inactivation of the drug by bacterial transferase enzymes, which slightly modify the aminoglycoside
structure through acetylation or phosphorylation. Aminoglycoside usage may be complicated by
nephrotoxicity, ototoxicity, or neuromuscular damage. They should
not be used during pregnancy as they are also a teratogen.
Incorrect Answers: A, B, D, and E.
Fluoroquinolones (Choice A) include ciprofloxacin, levofloxacin, and moxifloxacin. They inhibit
prokaryotic DNA gyrase (also known as topoisomerase). Potential side effects include vascular damage,
cartilage damage, tendonitis, or tendon rupture. They do not work
synergistically with aminoglycosides.
