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* NBME 13 answer key
  jasmin000 - 05/03/12 19:54

Some questions are missing in the download for block 1 and 2. Block 2 q 23..not sure if its A, hence the (). Open for discussion people!

Block 1

21. -HEAA
36. A-DAD
46. DDC-F

Block 2

6. C-BCA
21. BD(A)DD
26. BBCD-
41. CC-AE
46. FD-EB

Block 3


Block 4

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* Re:NBME 13 answer key
  gejorcla - 05/08/12 20:36
  BTW, i appreciate your hard work for posting all of these questions and asnwers on this site. thanks!
question 46 section one should not be D. I dont have all the questions, but i can see the wrong ones. I marked A on question 46 section one and I don't have that question among my incorrect questions, so it gotta be right.
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* Re:NBME 13 answer key
  wolverine99 - 05/08/12 20:44
  agree sec 1 q 46 A  
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* Re:NBME 13 answer key
  gejorcla - 05/08/12 21:37
  i want to say that my test had the same questions in a different order. so the asnwer key jasmin posted is good for the questions she posted in that order only. what i did to check with mine is: i dowloaded her questions and checked one by one with her key. i took my test yesterday so i still remember what i marked when i saw the questions. i bought the extended version which allows me to see the incorrect questions, so i can compare with the pictures i downloaded. i just thought i would point it out because at first i couldnt figure out why the asnwer key was so different from my asnwers. then when i finally got to see the questions i could tell that the order is completely different. they are the same questions though.
thnaks for doing this. it's a great idea!
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* Re:NBME 13 answer key
  gejorcla - 05/08/12 23:30
  i'm wondering about block 4 question 50. the key posted here says the correct asnwer is C . i don't know the correct asnwer but by what i have read to me the asnwer is A. anybody knows the explanation for this question?  
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* Re:NBME 13 answer key
  rani29 - 05/15/12 18:56
  can you please email me the questions, the link wont work for me :(
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* Re:NBME 13 answer key
  onyx88 - 05/18/12 05:28
  1- (D) doesn’t enjoy being with people, prefers individual activities, indifferent to sexual intimacy --> Schizoid
2- (F) Uterosacral Ligament is the only structure that extends posteriorly
3- (D) young female, neurological symptoms, white matter plaques --> Multiple Sclerosis
4- (D) Local IL-1 and TNF effects lead to activation of osteoclasts and bone resorption--> hypercalcemia
5- (E) Ischemia stimulates baroreceptors in afferent arterioles--> increased renin
6- (F) Cocaine works by inhibiting NE reuptake at the presynaptic terminals
7- (D) Post partum hemorrhage, placenta adherent to the uterus, no decidua--> Placenta accrete
8- (D) NE acts on B1 receptors in the SA node, AV node and cardiac myocytes to increase rate and contractility
9- (C) Chronic mal-absorption leading to signs of severe vitamin deficiencies (retinal degeneration, ataxia, motor dysfunction) + acanthocytosis + low cholesterol--> abetalipoproteinemia due to Apo B 100 deficiency
10- (C) Exposure to paint thinner + ophthalmologic and neurologic symptoms + anion gap metabolic acidosis--> probably methanol exposure which is metabolized by Formaldehyde dehydrogenase
11- (F) Parasympathetic innervation to the stomach provided by the vagal trunks increases acid output; other choices are all sympathetic
12- (C) Inheritance passed by female to 100% of offspring--> mitochondrial; variation in symptoms explained by Heteroplasmy
13- (D) CRF in middle age + family history + bilateral abdominal masses--> Polycystic kidney disease
14- (A) Long-term heavy smoker, painless hematuria--> most probably Bladder Cancer
15- (B) Abdominal pain, nausea, vomiting short time after eating pastries + no fever--> Enterotoxin ingestion
16- (C) Chronic transplant rejection carried out by CD8+ T cells is due to Direct cytotoxicity to graft cells
17- (B) Withdrawal symptoms of Heroin include hyper-excitability and increased sympathetic discharge
18- (A) History of hypercoagulability and miscarriage + prolonged PTT--> Antiphospholipid antibody syndrome
19- (B) Interferon-y receptor deficiency leads to defective intracellular killing of mycobacteria by macrophages
20- (F) All symptoms suggestive of scleroderma which leads esophageal fibrosis--> decreased peristalsis and LES tone.
22- (H) HSV becomes protected from immune response by establishing a latent infection in the sensory nerve cells, in case of genital herpes in the dorsal root ganglia of the lumbar or sacral plexus.
23- (E) The most common cardiac tumor in adults, in addition to being a famous source of embolism is myxoma, usually in the left atrium
24- (A) The clinical picture is suggestive of tetanus poisoning due to wound infection by clostridium tetani, the toxin works by inhibiting the release of the inhibitory neurotransmitter glycine in the spinal cord leading to disinhibition of the motor nerve cells
25- (A) The clinical picture is suggestive of Cushing disease due to increased ACTH secretion by pituitary adenoma leading to hyperplasia of the cells in the zona fasciculata of the adrenal glands
26- (A) The antibody worked by blocking the tumor receptor on the surface of hepatocytes, preventing tumor cells from homing to the liver cells
27- (D) Absence of blinding in the study created an observer bias which led to variability in outcome assessment
28- (C) The patient is clearly affected by the severity of his pain, he hasn’t attempted suicide on his own so I think restraining him wouldn’t be of benefit, reevaluating him after controlling the precipitating factor (i.e. the pain) would be the best option
29- (D) The patient’s behavior is strongly related to instances in which she becomes separated from her mother which can be considered normal behavior only between 12-18 months of age, in addition no signs of defiant or criminal behavior to justify oppositional defiant or conduct disorders, respectively.
30- (E) Variation in phenotype between individuals carrying the same genotype defines variable expressivity
31- (E) Acetazolamide acts by inhibiting bicarbonate reabsorption and hydrogen ion secretion in the proximal tubule
32- (E) The photograph shows a collection of blood vessels of abnormal shape in the medial side of the brain, together with the history of seizures this is suggestive of congenital vascular malformation
33- (D) History of amenorrhea and infertility + obesity + hirsutism--> polycystic ovarian syndrome
34- (A) Micafungin, like capsofungin, works by inhibiting carbohydrate synthesis in the fungal cell wall
35- (B) The patient’s diet rules out dietary deficiency as a cause, besides there is a high incidence of other autoimmune disorders in patients who have autoimmune thyroiditis, among those is pernicious anemia
36- (A) Ligaments, like cartilage are avascular and therefore lack of good blood supply would slow down the healing process
38- (D) History and symptoms are suggestive of heart failure, the presence of lowered PO2 indicates respiratory insufficiency which in case of heart failure is commonly caused by pulmonary edema
39- (A) The presence of alveolar hyaline membranes is indicative of ARDS which is the only acute process involving diffuse alveolar damage, the other choices all indicate a chronic process
40- (D) The HSG shows a malformed unicornuate uterus which is caused by the dysgenesis of the paramesonephric ducts
41- (A) The lab findings show hyponatremia and decreased plasma osmolality and increased urine osmolality indicative of hypersecretion of ADH
42- (C) Warfarin causes a decrease in factors II, VII, IX, and X, its toxicity can be treated by vit. K in mild cases and fresh frozen plasma in severe cases
43- (C) The photo shows gram positive bacilli, the only one from the choices that’s fits the description is Listeria
44- (C) Left sided numbness and paralysis that are more severe in the face and upper limb--> middle cerebral artery infarction
45- (D) Since the neurovascular bundle runs in the lower part of the rib all the choices with “below” can be ruled out. The only left choice that’s below 7th rib is (D). In addition thoracentesis should be done between 8th and 10th ribs to avoid lung injury
46- (A) The presence of adhesins (pilli) aids the bacteria in adhering to the urinary tract epithelium and withstanding the urine flow
47- (D) LD= Vd X Css= 8 X 0.35= 2.8 mg/kg X 55 kg = 154 mg
48- (C) The most beneficial drug in hepatic encephalopathy is lactulose, works by trapping ammonium in the intestines.
50- (F) The case indicates nephrogenic DI, the proximal tubule is always isotonic. The ADH works on the distal tubule and collecting ducts, when its action is blocked the osmolality inside these regions will be hypotonic
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* Re:NBME 13 answer key
  lifeformd - 05/18/12 10:30
  onyx88...thank u.
can u pls post rest of the blocks this way ?its a great help for many of us...
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* Re:NBME 13 answer key
  onyx88 - 05/19/12 02:56
  sure, am working on it, but I strongly advice everyone to take the online form first because it's a wonderful way of assessment, and then come back later to check the wrong answers. Taking the offline one would only be like solving some extra questions from any other question bank  
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* Re:NBME 13 answer key
  onyx88 - 05/19/12 13:53
  Block 2:

1- (D) Cephalexin like all other b-lactams works by inhibiting bacterial cell wall synthesis
2- (A) Hypoglycemia triggers glucagon release which activates adenylyl cyclase in the liver leading to glycogen breakdown
3- (B) Hereditary hemochromatosis is caused by increased absorption of iron from the small intestine
4- (A) History indicating a case of pulmonary embolism, in which perfusion is cut while ventilation remains normal
5- (B) Cisplatin works by cross-linking DNA
6- (C) Tachycardia and hypotension + the other symptoms are suggestive of ongoing hemorrhage, the presence of weak pulse in lower limbs makes leaking aortic aneurysm the most probable answer
8- (B) Winging of the scapula after mastectomy--> long thoracic nerve injury
9- (C) Typical case of multiple myeloma
10- (A) Unilateral headache and tearing and rhinorrhea + symptoms occur regularly every day at the same time and at same period over years --> cluster headache
11- (A) The description typically fits apoptosis, the man probably was suffering from acute viral hepatitis
12- (C) The woman’s history is suggestive of atherosclerosis which is a risk factor for ischemic colitis, in addition the splenic flexure is a “watershed area” between the middle and left colic arteries and is most commonly affected in cases of ischemic colitis
13- (C) Homologous pairing is essential for crossing over, in which homologous chromosomes exchange segments with each other during meiosis 1, this is necessary for genetic variation
14- (B) Typical case of Goodpasture’s syndrome in which antibodies attack basement membranes, causing crescentric glomerulonephritis with linear immunoflourescence and alveolar damage
15- (D) Old age, left lower quadrant pain, fever + typical CT scan findings--> diverticulitis
16- (E) Since the antigen was a polysaccharide it generated only a B cell response which led to only IgM production. IgG response requires isotype switching from IgM which depends on T cell stimulation to B cells, T cells in that case were not stimulated because they recognize only protein antigens not polysaccharides.
17- (B) The reason for increased risk of gastric adenocarcinoma in the Japanese population is the carcinogens present in the diet, the patient continued consuming the same diet after his arrival.
18- (C) Overdosage of neostigmine caused desensitization of the nicotinic receptors at the motor end plate. MG is due to autoimmune “deactivation” of nicotinic receptors, so choice A and other choices involving muscarinic receptors can be ruled out.
19- (D) Hand cleansing is generally the most important and effective measure in preventing nosocomial infections, not sure however about choice (B), someone else should confirm
20- (E) Praziquantel is the only choice that works by the way described in the question stem
21- (B) Elbow flexion is done mainly by the biceps and brachialis muscles, both supplied by the musculocutaneous nerve.
22- (D) Imprinting in that case caused Prader-Willi syndrome because he inherited the defective chromosome from his father, while his cousin has Angelman syndrome because she inherited that chromosome from her mother.
23- (E) As the stimulation frequency increases the amount of calcium released from the sarcoplasmic reticulum increases, and so the amount of calcium sequestered in order to be able to release a greater amount of calcium with each successive contraction.
24- (D) The results show that those who have a high selenium diet have 0.3 the risk of those who have a diet low in selenium (i.e. a lower risk), and since the CI doesn’t contain 1 the result can be considered significant.
25- (D) Premature baby with respiratory distress + typical findings on CXR--> neonatal RDS due to surfactant deficiency.
26- (E) That’s the function of myeloperoxidase; converting hydrogen peroxide into hyalide radicals
27- (B) Using compression sleeves is one of the recommended treatments for lymphedema
28- (C) The lab results show severe anemia with normal MCV (so it’s neither iron nor B12 deficiency), they also show high creatinine and BUN (consistent with Hx of DM) so the most probable cause of the anemia is chronic renal failure
29- (D) The history suggests minimal change nephropathy, a disease characterized by heavy selective proteinuria due to loss of negative charge in the glomerular basement membrane
31- (F) Slow nerve conduction indicates a problem in the myelin sheath, leading to slowing down of action potential propagation; the latter depends on voltage gated Na channels. Neurotransmitter gated channels serve to make the initial excitation to the nerve, so their impairment would lead to absent impulse not slowed conduction.
32- (B) Tough one! Quote: “The first step in population sampling is identifying the population which the researchers wish to learn more about. If, for example, someone wants to find out how many African Americans have cats, the researchers know that the population under scrutiny is the African American community. Population sampling is used to select representative individuals from this vast community so that an estimate about cat ownership among other members of this community can be extrapolated. On the other hand “convenience sampling “ is the one in which a sample of readily accessible individuals is used, rather than a diverse sample of larger population.” This link explains it all
33- (D) Classical example and photo of subarachnoid hemorrhage
34- (B) Tachycardia, hypertension, papillary dilatation and diaphoresis all point out to increased sympathetic discharge typical of amphetamine and cocaine intoxication
35- (D) Hemidesmosomes anchor basal cells of the epidermis to the basement membrane; the case described is a case of bullous pemphigoid. Desmosomes on the other hand serve to attach the cells of the epidermis to each other not to BM, and they are destroyed in pemphigus vulgaris.
36- (E) The man most probably has immotile cilia syndrome which is characterized by sinusitis, bronchiectasis, immotile sperms, and usually situs inversus totalis.
37- (D) The description typically fits pheochromocytoma, when such a tumor occurs outside the adrenal gland, it is called paraganglioma.
38- (B) The organism described is pseudomonas aeroginosa, normally it is not encapsulated, but in cystic fibrosis the organism produces a capsule of sodium alginate that forms a biofilm around the organism and makes it difficult for antibiotics to penetrate.
39- (E) Typical description of pneumocytes type II that produce surfactant.
40- (E) History of hypovolemia and urine analysis shows: granular cast, oliguria, increased sodium excretion (>1%), and fixed osmolality. All points to acute tubular necrosis which is a reversible condition; upon restoration of normal blood volume, the tubular cells regenerate.
41- (C) The pulmonary circulation originates from the right ventricle and receives all of the cardiac output; the bronchial circulation on the other hand originates from left ventricle and is part of the systemic circulation and so receives only a part of the cardiac output.
42- (C) History of amenorrhea for two months without any associated symptom or sign puts pregnancy on top of the list; best thing to rule it out is doing serum B-HCG.
43- (A) The only open-ended question, the others jump to assumptions and in addition all contain closed-ended questions.
45- (E) Ubiquitination of the misfolded proteins (tagging them with ubiquitin protein) is the signal for the proteasome to attack these misfolded proteins.
46- (F) Testosterone is the only choice of which decreased concentration would lead to erectile dysfunction.
47- (D) A case of disuse atrophy in which there is increased protein degradation in the muscle cells leading to decrease in their size, but they don’t die, it is a reversible a condition.
49- (E) Induction of cytochrome P450 by alcohol leads to increased metabolism of acetaminophen by this enzyme, which leads to increased production of hepatotoxic metabolites. This is how alcohol lowers the threshold for acetaminophen toxicity.
50- (B) Treatment of infertility of unapparent cause often starts with a trial to increase the ovulation in order to increase the probability of fertilization; the drug most commonly used to induce ovulation is clomiphine citrate.
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* Re:NBME 13 answer key
  waseem_khedr - 05/19/12 17:18
great efforts i really appreciate yr efforts and i am really benifit of your explanations >>>>>>>>>>>>>please cotinue the remaining 2 blocks as such
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