USMLE STEP 3 HIGH YIELD
FACTS 2 EXAM 2025 QUESTIONS
AND ANSWERS
What protein is most likely involved in the transport process leading to
disease recurrence of Herpes?
Kinesin
= Anterograde transport of virus
= motor protein that moves intracellular cargo (organelles, viral particles)
away from nucleus, down axon, & toward nerve terminal
- powered by ATP hydrolysis
- guided by microtubule filaments
Microtubular motor protein that participates in retrograde axonal transport
(moving organelles toward nucleus). Establishes latent phase following
primary HSV infection.
Dynein
Intermediate filament expressed in mesenchymal cells.
Vimentin
- secures organelles inside cytosol
- resistance to mechanical stress
,Tendency of study subjects to change their behavior as a result of their
awareness that they are being studied.
Hawthorne effect (observer effect)
Selection bias created by choosing hospitalized patients as control group.
Berkson's bias
Patient homozygous for apolipoprotein E-4 allele likely to suffer from
Alzheimer dementia
Early-onset Alzheimer disease associated with 3 gene mutations
APP = chromosome 21
presenilin 1
presenilin 2
Cells that mediate hypersensitivity reaction of Candida extract skin reaction
T-lymphocytes
Delayed-type HS reaction (DTH)
- contact dermatitis, granulomatous inflammation, tuberculin skin test
- mediated by T-lymphocytes
,= 1-2 days following antigen exposure why you wait 48-72 hours for annual
PPD test to be read!
6-year-old boy evaluated for recurrent infections & failure to thrive. He has
been hospitalized for pneumococcal pneumonia twice & has had 5
episodes of otitis media, requiring placement of tympanosotomy tubes. The
patient also has a history of prolonged diarrhea caused by Cryptosporidium
parvum. Physical exam shows large tonsils, palpable lymph nodes, &
hepatosplenomegaly. Further evaluation shows that the patient has
defective signaling between CD4+ T cells & B lymphocytes. What
immunoglobulins likely has the highest serum concentration in this patient?
IgM
Hyperimmunoglobulin M syndrome
- defect in class switching in B lymphocytes
- defective CD40L on Th cells --> class switching defect
- high IgM
- low IgG, IgA, IgE
- recurrent sinopulmonary, GI, & opportunistic infections (Pneumocystis,
Cryptosporidium)
Bladder functioning of patients with multiple sclerosis
Bladder hypertonia via urodynamic studies
- develop spastic bladder few weeks after developing acute lesion of spinal
, cord
- increased urinary frequency & urge incontinence
Most common cause of Candida vaginitis
Antibiotic use via reduction of lactobacilli population
--> facilitates Candida overgrowth
Key NTs involved in pathophysiology of ADHD
NE & DA
- stimulant drugs (methylphenidate & amphetamineds) = first-line drug
treatments for school-aged children with ADHD
Causes of Right shift in oxygen-Hb dissociation curve
ACE BATs right handed
Acid
CO2
Exercise
2,3-BPG
Altitude
Temperature
Anemia
- can cause lactic acidosis
FACTS 2 EXAM 2025 QUESTIONS
AND ANSWERS
What protein is most likely involved in the transport process leading to
disease recurrence of Herpes?
Kinesin
= Anterograde transport of virus
= motor protein that moves intracellular cargo (organelles, viral particles)
away from nucleus, down axon, & toward nerve terminal
- powered by ATP hydrolysis
- guided by microtubule filaments
Microtubular motor protein that participates in retrograde axonal transport
(moving organelles toward nucleus). Establishes latent phase following
primary HSV infection.
Dynein
Intermediate filament expressed in mesenchymal cells.
Vimentin
- secures organelles inside cytosol
- resistance to mechanical stress
,Tendency of study subjects to change their behavior as a result of their
awareness that they are being studied.
Hawthorne effect (observer effect)
Selection bias created by choosing hospitalized patients as control group.
Berkson's bias
Patient homozygous for apolipoprotein E-4 allele likely to suffer from
Alzheimer dementia
Early-onset Alzheimer disease associated with 3 gene mutations
APP = chromosome 21
presenilin 1
presenilin 2
Cells that mediate hypersensitivity reaction of Candida extract skin reaction
T-lymphocytes
Delayed-type HS reaction (DTH)
- contact dermatitis, granulomatous inflammation, tuberculin skin test
- mediated by T-lymphocytes
,= 1-2 days following antigen exposure why you wait 48-72 hours for annual
PPD test to be read!
6-year-old boy evaluated for recurrent infections & failure to thrive. He has
been hospitalized for pneumococcal pneumonia twice & has had 5
episodes of otitis media, requiring placement of tympanosotomy tubes. The
patient also has a history of prolonged diarrhea caused by Cryptosporidium
parvum. Physical exam shows large tonsils, palpable lymph nodes, &
hepatosplenomegaly. Further evaluation shows that the patient has
defective signaling between CD4+ T cells & B lymphocytes. What
immunoglobulins likely has the highest serum concentration in this patient?
IgM
Hyperimmunoglobulin M syndrome
- defect in class switching in B lymphocytes
- defective CD40L on Th cells --> class switching defect
- high IgM
- low IgG, IgA, IgE
- recurrent sinopulmonary, GI, & opportunistic infections (Pneumocystis,
Cryptosporidium)
Bladder functioning of patients with multiple sclerosis
Bladder hypertonia via urodynamic studies
- develop spastic bladder few weeks after developing acute lesion of spinal
, cord
- increased urinary frequency & urge incontinence
Most common cause of Candida vaginitis
Antibiotic use via reduction of lactobacilli population
--> facilitates Candida overgrowth
Key NTs involved in pathophysiology of ADHD
NE & DA
- stimulant drugs (methylphenidate & amphetamineds) = first-line drug
treatments for school-aged children with ADHD
Causes of Right shift in oxygen-Hb dissociation curve
ACE BATs right handed
Acid
CO2
Exercise
2,3-BPG
Altitude
Temperature
Anemia
- can cause lactic acidosis
