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* Need Explanations to NBME 19(Step 1)!Please help.
 #854332  
  blessedalways - 09/08/18 19:49
 
  Hello Everyone,

I know this is Step 2 Forum, but I cam on here because really would like if any of you bright minds can help answer these questions with clear explanations. Please help and it will mean so much to me.Thanks in advance!

1) A 5-year-old boy is brought to the physician because of pain in the right eye at night for the past week. There is no family history of neoplasia. Examination shows strabismus and tenderness in the eye. The left eye is normal. Examination of the retina shows the presence of a mass. The physician explains to the parents that the boy is unlikely to develop any other neoplasms. The first mutation leading to this neoplasm most likely occurred in which of the following?

A) Germ cells
B) Retinal cells
C) Somatic cells of the child
D) Somatic cells of the parents
E) Zygote


2) An 18-year-old woman comes to the physician to request screening for colon cancer. Her father and grandfather died of colon cancer at the ages of 36 and 45 years, respectively. Physical examination shows no abnormalities. Colonoscopy shows approximately 200 lesions throughout the colon. A colectomy is done, and a section of the colon removed is shown in the photograph. Which of the following is the chance that this patient's offspring will eventually develop adenocarcinoma of the colon?

A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

3) A 27-year-old woman has an episode of pneumococcal pneumonia that is treated with penicillin. After 2 days of therapy, she is afebrile and has improved pulmonary function. Four days later, she becomes jaundiced and has anemia characterized by an increased reticulocyte count and an increased serum unconjugated bilirubin concentration. Which of the following tests most likely explain her present findings?

A) Direct antiglobulin (Coombs) test
B) Serum antinuclear antibody assay
C) Serum ferritin measurement
D) Serum lactate dehydrogenase assay
E) Urinary protoporphyrin measurement

4) A 30- year-old woman undergoes a cervical biopsy because of a Pap smear showing a high-grade intraepithelial lesion. Which of the following locations of the neoplastic cells in the tissue sample is most consistent with in situ cervical carcinoma?

A) In the cervical stroma
B) In the cervical venules
C) In the iliac lymph nodes
D) In the myometrium
E) Superficial to the basement membrane

5) A 35- year-old man comes to the physician to discuss donating a kidney to his 39-year-old sister who has type 1 diabetes mellitus and chronic renal failure. He has no history pf major medical illness, and physical examination shows no abnormalities. Which of the following best decribes the likelihood that this donor's human leukocyte antigen tyoe will match that of his sister?

A) 1.1
B) 1.2
C) 1.4
D) 1.6
E) 1.8

6) A 23-year-old woman comes to the student health center because of a 2-week history of a vaginal sore. She has been sexually active with a new partner, and they use condoms inconsistently. Pelvic examination shows a nontender ulcer on the vulva. Dark-field examination of scraping of the lesion is positive for spirochetes. Which of the following histologic changes is most likely to b seen on a biopsy specimen of this lesion?

A) Acute inflammation with abscess formation
B) Granulomas with caseation and plasma cell infiltration
C) Granulomas with suppuration
D) Obliterative endarteritis with lymphocytes and plasma cells
E) Pyogranulomatous inflammation with edema

7) A 17-year -old boy is brought to the emergency department on a hot summer day after he collapses while working as a traffic controller for a road construction crew. When he was 4 years old, he was treated with numerous skin grafts after sustaining full-thickness burns involving 30% of his body surface area. Examination shows hyperthermia. Which of the following is the most likely explanation for this occurence?

A) The burn scars and skin grafts lack eccrine glands, limiting his ability to sweat
B) Central thermoregulation is inadequate
C) Injured skin is more likely to release endogenous pyrogens increasing core temperature
D) Skin grafts and scars are more sensitive to heat and sun light

8) A 60-year- old man with a 20-year history of hypertension comes to the physician because of shortness of breath and fatigue for 3 months. The shortness of breath is exacerbated by climbing stairs. His pulse is 80min, and blood pressure is 100/70 mm Hg. Physical examination shows peripheral cyanosis. Crackles are heard bilaterally on auscultation of the findings in this patient?

Cardiac Output CVP

A) Decreased decreased
B) Decreased increased
C) Decreased no change
D) Increased decreased
E) Increased increased
F) Increased no change
G) No change decreased
H) No change increased
I) No change no change

9) A healthy 23- year-old woman engages in strenuous aerobic exercise for 30 minutes. Which of the following best describes the total cross-sectional area of the pulmonary microcirculation in this woman during exercise?

A) Decreased, as a result of increased carbon dioxide levels in blood
B) Decreased , in proportion to the increased resisitance
C) Increased, as a result of distension and recruitment of microvessels
D) Increased, as a result of myogenic reflexes
E) Unchanged

10) During an experiment, an isolated skeletal muscle is placed in a bath with a high concentration of glucose for 2 hours. The muscle is then contracted with electrical stimulation. An intracellular decrease in which of the following most likely indicates the onset of muscle fatigue?

A) ADP
B) Inorganic phosphate
C) Inosine monophosphate
D) Lactate
E) pH

11) A 13-year- old girl grew 7.5 cm (3in) over the summer. Which of the following most likely accounts for increased intestinal absorption of calcium during this period?

A) Calcitonin-mediated hypercalcemia
B) Calcium-binding proteins in goblet cells
C) Cortisol-induced transcription of calcium transporters
D) Cyclic AMP generated in the enterocytes in response to parathyroid hormone
E) Hormones derived from 7-dehydrocholestrol

12) A 40-year-old man comes to the physician because of a 1-month history of increasing malaise, nausea, and abdominal pain and a 1-week history of light-colored stools. Abdominal examination shows tenderness of the right upper quadrant. Laboratory studies show:

Leukocyte count 10,000/mm3
Serum
Bilirubin, total 4 mg/dL
Alkaline phosphate 180 U/L
AST 1500 U/L
Serology
Hepatitis B e antigen (HBeAg) positive
Hepatitis B surface antigen (HBsAg) positive
Hepatitis B virus-DNA positive
IgG anti-HBsAg negatve
IgM anti-hepatitis B core antigen positive
IgM ant-HBeAg negative

Further observation shows that CD8+ T lymphocytes bind to antigens, resulting in liver injury. These antigens are most likely to occur in which of the following locations?

A) Bile duct epithelium
B) Hepatocytes
C) Ito cells
D) Kupffer cells
E) Stellate cells

14) The graph shows the rate of breakdown of skeletal muscle glycogen by phosphorylase in the presence and absence of AMP. Based on the data, which of the following best describes the action of AMP?

A) Allosteric activator
B) Allosteric inhibitor
C) Catabolite activator
D) Catabolite repressor
E) Covalent modifier of the enzyme
F) Covalent modifier of phosphorylase kinase

15) One year ago, a 15-year-old girl received a bone marrow transplant following a relapse of acute myelogenous leukemia. She now has a karyotype of 46 XY. The results of the karyotyping are most likely due to which of the following?

A) Male pseudohermaphroditism'
B) Nonautologous donor
C) Relapse of acute myelogenous leukemia
D) Total body irradiation-induced aberration
E) Underlying myelodysplasia

16) A 52-year-old is brought to the emergency department because of a 4-hour history of severe headache, anxiety, sweating, and palpitations. He has a 2-year history of hypertension well controlled with clonidine and hydrochlorothiazide, but he ran out of his prescriptions 3 days ago. His pulse is 120?min, and blood pressure is 170/110 mm Hg. Physical examination shows diaphoresis. Which of the following effects is most likely an injection of propranolol in this patient?

A) Decreased total peripheral resistance and decreased cardiac output
B) Decreased total peripheral resistance and increased cardiac output
C) Increased total peripheral resistance and decreased cardiac output
D) Increased total peripheral resistance and increased cardiac output
E) No change in total peripheral resistance or cardiac output

17) A 24-year-old man is evaluated because of sharp left-sided chest pain and dyspnea that occurred suddenly 4 hours ago. An x-ray of the chest is shown. Which of the following is the most likely cause of the x-ray findings?

A) Bronchoconstriction
B) Diaphragmatic paralysis
C) Loss of negative intrapleural pressure
D) Mucus obstruction of the left main bronchus
E) Respiratory muscle fatigue

18) A previously healthy 25-year-old man is brought to the emergency because of severe pain on the left side of his chest after falling from a ladder. The pain is sharp and stabbing and becomes more intense when the patient coughs or takes a deep breath. An x-ray of the chest shows fractures of four consecutive ribs on the left. There is no pneumothorax. Which of the following patterns represents the most likely changes in respiratory status caused by his injury?

Respiratory Rate Tidal Volume Airway Resistance (1 sec)

A) increase increase increase

B) increase no change increase

C) increase decrease no change

D) no change no change no change

E) decrease increase decrease

F) decrease decrease no change

G) decrease no change decrease

19) A 45-year-old patient with chronic alcohol dependence comes to the emergency department because of foul-smelling brownish sputum for the past 3 days. The patient has had several episodes of unconsciousness following bouts of heavy drinking over the past month. Which of the following x-rays of the chest shown most likely represents this patient?
There are pictures that I was not able to copy and paste on here, but please (anyone that knows) tell me how to be able to identify the X-ray for this type of diagnoses.
20) A 30-year-old man and a 24-year-old woman (indicated by the arrows) request preconceptional counseling because the man’s brother has type I oculocutaneous albinism. This is an autosomal recessive, single gene disorder thought to occur about once in every 40,000 persons in the general population. Assume that the alleles are in equilibrium in the population, that the woman’s family history is negative for this disorder, and that the two probands have neither shared relatives nor common ethnicity. A pedigree is shown. Which of the following is the best estimate that their child will be affected with oculocutaneous albinism?
A) 1 in 4
B) 1 in 100
C) 1 in 200
D) 1 in 600
E) 1 in 40,000

21) A newborn is delivered at term to a 40-year-old primigravid woman. Chorionic villus sampling at 15 weeks’ gestation was done, and results of chromosomal analysis showed a male fetus. Physical examination shows female external genitalia and absent internal genitalia. Further tests are most likely to determine that this child has a mutation preventing responses to which of the following hormones?

A) Estrogen
B) Follicle-stimulating hormone
C) Luteinizing hormone
D) Mullerian-inhibiting hormone
E) Testosterone

22) Serum cholesterol concentrations are measured as part of a community study. The mean and standard deviation are given for women by age group:
Age (years) Cholesterol (mg/dL)
45-49 229 + or – 47
50-54 246 + or – 50
55-59 255 + or – 48
60- 62 244 + or – 36

Assuming serum cholesterol concentrations follow a normal (Gaussian) distribution, which of the following is the probability that a woman between the ages of 50 and 54 years has a serum cholesterol concentration greater than 296 mg/dL?

A) 1%
B) 2.5%
C) 5%
D) 16%
E) 95%

23) In the diagram of proximal renal tubular epithelium, the labeled arrows denote pathways and mechanisms of net movement of water or solutes. Which of the following letters of the pathway best describes the transcriptional transport of water?

I was not able to copy and paste this picture on here, but can anybody please explain or where can I search for a pic that can identify this that is the same or similar to the pic on NBME 19?

24) During an experiment, it is found that instillation of lipid into the duodenum leads to the release of a hormonal substance from endocrine cells in the duodenal mucosa. Which of the following best describes the major physiologic action of this substance?

A) Gallbladder contraction
B) Increased gastric contractility
C) Pancreatic endocrine stimulation
D) Salivary gland stimulation
E) Splanchnic vasoconstriction

25) A 24-year-old man is brought to the emergency department 1 hour after a motor vehicle collision. He has lost an estimated 2 L of blood from the trauma associated with a left femoral fracture. His blood pressure is 70/40 mm Hg. Following immediate operative repair, physical examination shows multiple ecchymoses over the medial aspects of the upper arms. There is bleeding from venipuncture sited. Laboratory studies show:

Platelet count 75,000/mm3
Prothrombin time 21 sec (INR=1.7)
Partial thromboplastin time 56 sec
Plasma fibrinogen < 100 mg/dL (N= 200-400)

Which of the following coagulation abnormalities is most likely in this patient?

A) Consumption coagulopathy
B) Hemophilia A
C) Hemophilia B
D) Henoch-Schonlein purpura
E) Vitamin K deficiency
 
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