USMLE Exam Questions with 100.pdf

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1. In the synthesis of collagen, the hydroxylation of proline and lysine occurs in which of the following?* (A) Golgi apparatus (B) Secretory vesicles (C) Rough endoplasmic reticulum (D) Smooth e... ndoplasmic reticulum 2. A 12-year-old boy with muscular dystrophy is found to have a mutation of the gene that encodes the protein dystrophin. Genetic alterations in dystrophin lead to progressive muscular weakness because dystrophin provides structural support to the sarcolemma by binding which of the following?* (A) β-Dystroglycan to laminin (B) Actin to β-dystroglycan (C) Actin to the Z lines (D) Z lines to M lines 3. Patients with Cushing syndrome often show osteoporotic changes. Which one of the following is involved in the etiology of osteoporosis induced by Cushing syndrome?* (A) Decreased glucocorticoid levels that result in decreased quality of the bone deposited (B) Excess deposition of osteoid (C) Bone fragility resulting from excess bone resorption (D) Decreased PTH levels 4. A 59-year-old woman is admitted to the hospital because of agitation and aggression. Three years prior to admission her irregular, flinging movements had become so severe that she could not walk or assist in her own care. She is diagnosed with Huntington’s chorea, which is a hereditary disease affecting neurons within which of the following?* (A) Anterior cerebellum (B) Subthalamus (C) Substantial nigra (D) Striatum 5. A 2-day-old infant starts having brief tonic-clonic seizures throughout the day. His neurological function in between seizures is normal, and he has no other medical or neurological problems. The history reveals no readily apparent causes for the seizures though the mother recalled that her first baby also developed seizures shortly after birth that only lasted for 2 weeks, with no subsequent episodes or developmental problems. Genetic analysis revealed a mutation of voltage-gated K + channels consistent with a diagnosis of benign familial neonatal seizures. Which of the following would cause an immediate reduction in the amount of potassium leaking out of a cell?* (A) Increasing the permeability of the membrane to potassium (B) Hyperpolarizing the membrane potential (C) Decreasing the extracellular potassium concentration (D) Reducing the activity of the sodium-potassium pump [Show More]

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