USMLE EXAM zm
Exam Solution
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USMLE Step 1 uWorld High Yield Notes 2026 A+ GRAD
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E ASSURED COMPLETE SOLUTIONS AND VERIFIED ANS
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WERS (54FE3) zm
QUESTION 1 zm
What are the two major microtubular motor proteins? Which does anterograde axonal
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transport, which does retrograde axonal transport?
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ANSWER
Kinesin, Dynein Kinesin: Anterograde Dynein: Retrograde`
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QUESTION 2 zm
What do you think, immunologically speaking, when you see someone with recurrent
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Neisseria infections? zm
ANSWER
Inability to form the membrane attack (MAC) complex this is a common complement deficiency
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QUESTION 3 zm
What is the defect in Chronic Granulomatous disease? What is the pathophysiology?
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ANSWER
NADPH Oxidase deficiency leads to the inability to kill intracellular organisms
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QUESTION 4 zm
Characteristic triad of ataxia telangiectasia? zm zm zm zm
ANSWER
cerebellar ataxia, telangiectasias, increased risk of sinopulmonary infections
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,QUESTION 5 zm
What is the major immune deficiency of ataxia telangiectasia?
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ANSWER
IgA deficiency, which predisposes to infections of the upper and lower airways (and other mucous
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membranes)
QUESTION 6 zm
There's a useful mnemonic for Ataxia Telangiectasia and the gene that's mutated. Wha
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t is it?
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ANSWER
ATM Ataxia Telangiectasia Mutated ATM gene is responsible for DNA break repair
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QUESTION 7 zm
What is one reason that lead intoxication causes hypochromic anemia?
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ANSWER
Mitochondrial iron transport is important for Heme synthesis! It's inhibited by lead. So you don't ma
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ke heme in your mitochondria and you get hypochromic anemia.
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QUESTION 8 zm
What is the biochemical problem in Lesch-
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Nyhan syndrome? (And, only if you got that right, what are the really cool symptoms
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of it?)
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ANSWER
Defective purine catabolism, so buildup of purines. It's an X-
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linked recessive disorder with mutated HGPRT gene (hypoxanthine-
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guanine phosphoribosyltransferase, if you want to impress people). Now, if you got HGPRT and puri
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ne catabolism right, you can say: self-
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mutilating behavior on top of mental retardation, choreoathetoid (think Chorea) movements and spa
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sticity.
QUESTION 9 zm
What is the defect in Niemann-
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Pick disease? What causes that? What is the common macular finding?
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ANSWER
,Sphingolipid degradation is defective Caused by an autosomal recessive defect in sphingomyelinase C
zm zm zm zm zm zm zm zm zm zm zm zm
herry Spot on the macula? Niemann Pick's or Tay Sach's.
zm zm zm zm zm zm zm zm zm
QUESTION 10 zm
If a baby gets exposed to an unclean knife (...) and subsequently develops rigid paraly
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sis, what is the diagnosis, where do we think this might happen, and how do we prev
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ent it?zm
ANSWER
Neonatal Tetanus Developing Countries Maternal immunization with tetanus toxoid is the best way t
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o prevent it an adeuately immunized mom will transfer IgG's across the placenta to the neonate
zm zm zm zm zm zm zm zm zm zm zm zm zm zm zm
QUESTION 11 zm
Which microtubule associated protein aids in anterograde transport of intracellular ve
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sicles and organelles? Which end of the microtubule do they go towards?
zm zm zm zm zm zm zm zm zm zm zm
ANSWER
Kinesin. Towards the (+) rapidly growing end.
zm zm zm zm zm zm
QUESTION 12 zm
What is an early BRAIN finding of Ataxia-
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Telangiectasia and how does it manifest itself? zm zm zm zm zm zm
ANSWER
Cerebellar atrophy manifests as ataxia in the first years of life.
zm zm zm zm zm zm zm zm zm zm
QUESTION 13 zm
High yield path association for Alzheimer's disease?
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ANSWER
Neurofibrillary tangles in the neocortex zm zm zm zm
QUESTION 14 zm
High yield path association for Parkinson's disease?
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ANSWER
Loss of neurons in the substantia nigra
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, QUESTION 15 zm
High yield path association for Huntington disease?
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ANSWER
Atrophy of caudate nucleus
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QUESTION 16 zm
What are the major manifestations of Ataxia-telangiectasia?
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ANSWER
cerebellar ataxia, oculocutaneous tenlangiectasias, repeated sinopulmonary infections, and an increas
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ed incidence of malignancy
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QUESTION 17 zm
If you heard: amenorrhea, bitemporal hemianopsia, and enlargement of the pituitary g
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land on brain imaging, what would you be thinking?
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ANSWER
Prolactinoma, the most common pituitary adenoma.
zm zm zm zm zm
QUESTION 18 zm
What embryological layer is the anterior pituitary derived from?
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ANSWER
Surface ectoderm zm
QUESTION 19 zm
What is the most common congenital abnormality associated with the use of Sodium V
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alproate during pregnancy? zm zm
ANSWER
neural tube defects, e.g., meningocele because valproate inhibits intestinal folic acid absorption result
zm zm zm zm zm zm zm zm zm zm zm zm
ing in teratogenicity
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QUESTION 20 zm
What is the characteristic histology of a craniopharyngioma?
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Exam Solution
zm
USMLE Step 1 uWorld High Yield Notes 2026 A+ GRAD
zm zm zm zm zm zm zm zm zm
E ASSURED COMPLETE SOLUTIONS AND VERIFIED ANS
zm zm zm zm zm zm
WERS (54FE3) zm
QUESTION 1 zm
What are the two major microtubular motor proteins? Which does anterograde axonal
zm zm zm zm zm zm zm zm zm zm zm
transport, which does retrograde axonal transport?
zm zm zm zm zm zm
ANSWER
Kinesin, Dynein Kinesin: Anterograde Dynein: Retrograde`
zm zm zm zm zm
QUESTION 2 zm
What do you think, immunologically speaking, when you see someone with recurrent
zm zm zm zm zm zm zm zm zm zm zm zm
Neisseria infections? zm
ANSWER
Inability to form the membrane attack (MAC) complex this is a common complement deficiency
zm zm zm zm zm zm zm zm zm zm zm zm zm
QUESTION 3 zm
What is the defect in Chronic Granulomatous disease? What is the pathophysiology?
zm zm zm zm zm zm zm zm zm zm zm
ANSWER
NADPH Oxidase deficiency leads to the inability to kill intracellular organisms
zm zm zm zm zm zm zm zm zm zm
QUESTION 4 zm
Characteristic triad of ataxia telangiectasia? zm zm zm zm
ANSWER
cerebellar ataxia, telangiectasias, increased risk of sinopulmonary infections
zm zm zm zm zm zm zm
,QUESTION 5 zm
What is the major immune deficiency of ataxia telangiectasia?
zm zm zm zm zm zm zm zm
ANSWER
IgA deficiency, which predisposes to infections of the upper and lower airways (and other mucous
zm zm zm zm zm zm zm zm zm zm zm zm zm zm zm
membranes)
QUESTION 6 zm
There's a useful mnemonic for Ataxia Telangiectasia and the gene that's mutated. Wha
zm zm zm zm zm zm zm zm zm zm zm zm
t is it?
zm zm
ANSWER
ATM Ataxia Telangiectasia Mutated ATM gene is responsible for DNA break repair
zm zm zm zm zm zm zm zm zm zm zm
QUESTION 7 zm
What is one reason that lead intoxication causes hypochromic anemia?
zm zm zm zm zm zm zm zm zm
ANSWER
Mitochondrial iron transport is important for Heme synthesis! It's inhibited by lead. So you don't ma
zm zm zm zm zm zm zm zm zm zm zm zm zm zm zm
ke heme in your mitochondria and you get hypochromic anemia.
zm zm zm zm zm zm zm zm zm
QUESTION 8 zm
What is the biochemical problem in Lesch-
zm zm zm zm zm zm
Nyhan syndrome? (And, only if you got that right, what are the really cool symptoms
zm zm zm zm zm zm zm zm zm zm zm zm zm zm zm
of it?)
zm
ANSWER
Defective purine catabolism, so buildup of purines. It's an X-
zm zm zm zm zm zm zm zm zm
linked recessive disorder with mutated HGPRT gene (hypoxanthine-
zm zm zm zm zm zm zm
guanine phosphoribosyltransferase, if you want to impress people). Now, if you got HGPRT and puri
zm zm zm zm zm zm zm zm zm zm zm zm zm zm
ne catabolism right, you can say: self-
zm zm zm zm zm zm
mutilating behavior on top of mental retardation, choreoathetoid (think Chorea) movements and spa
zm zm zm zm zm zm zm zm zm zm zm zm
sticity.
QUESTION 9 zm
What is the defect in Niemann-
zm zm zm zm zm
Pick disease? What causes that? What is the common macular finding?
zm zm zm zm zm zm zm zm zm zm
ANSWER
,Sphingolipid degradation is defective Caused by an autosomal recessive defect in sphingomyelinase C
zm zm zm zm zm zm zm zm zm zm zm zm
herry Spot on the macula? Niemann Pick's or Tay Sach's.
zm zm zm zm zm zm zm zm zm
QUESTION 10 zm
If a baby gets exposed to an unclean knife (...) and subsequently develops rigid paraly
zm zm zm zm zm zm zm zm zm zm zm zm zm zm
sis, what is the diagnosis, where do we think this might happen, and how do we prev
zm zm zm zm zm zm zm zm zm zm zm zm zm zm zm zm
ent it?zm
ANSWER
Neonatal Tetanus Developing Countries Maternal immunization with tetanus toxoid is the best way t
zm zm zm zm zm zm zm zm zm zm zm zm zm
o prevent it an adeuately immunized mom will transfer IgG's across the placenta to the neonate
zm zm zm zm zm zm zm zm zm zm zm zm zm zm zm
QUESTION 11 zm
Which microtubule associated protein aids in anterograde transport of intracellular ve
zm zm zm zm zm zm zm zm zm zm
sicles and organelles? Which end of the microtubule do they go towards?
zm zm zm zm zm zm zm zm zm zm zm
ANSWER
Kinesin. Towards the (+) rapidly growing end.
zm zm zm zm zm zm
QUESTION 12 zm
What is an early BRAIN finding of Ataxia-
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Telangiectasia and how does it manifest itself? zm zm zm zm zm zm
ANSWER
Cerebellar atrophy manifests as ataxia in the first years of life.
zm zm zm zm zm zm zm zm zm zm
QUESTION 13 zm
High yield path association for Alzheimer's disease?
zm zm zm zm zm zm
ANSWER
Neurofibrillary tangles in the neocortex zm zm zm zm
QUESTION 14 zm
High yield path association for Parkinson's disease?
zm zm zm zm zm zm
ANSWER
Loss of neurons in the substantia nigra
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, QUESTION 15 zm
High yield path association for Huntington disease?
zm zm zm zm zm zm
ANSWER
Atrophy of caudate nucleus
zm zm zm
QUESTION 16 zm
What are the major manifestations of Ataxia-telangiectasia?
zm zm zm zm zm zm
ANSWER
cerebellar ataxia, oculocutaneous tenlangiectasias, repeated sinopulmonary infections, and an increas
zm zm zm zm zm zm zm zm zm
ed incidence of malignancy
zm zm zm
QUESTION 17 zm
If you heard: amenorrhea, bitemporal hemianopsia, and enlargement of the pituitary g
zm zm zm zm zm zm zm zm zm zm zm
land on brain imaging, what would you be thinking?
zm zm zm zm zm zm zm zm
ANSWER
Prolactinoma, the most common pituitary adenoma.
zm zm zm zm zm
QUESTION 18 zm
What embryological layer is the anterior pituitary derived from?
zm zm zm zm zm zm zm zm
ANSWER
Surface ectoderm zm
QUESTION 19 zm
What is the most common congenital abnormality associated with the use of Sodium V
zm zm zm zm zm zm zm zm zm zm zm zm zm
alproate during pregnancy? zm zm
ANSWER
neural tube defects, e.g., meningocele because valproate inhibits intestinal folic acid absorption result
zm zm zm zm zm zm zm zm zm zm zm zm
ing in teratogenicity
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QUESTION 20 zm
What is the characteristic histology of a craniopharyngioma?
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