Metabolism — MCQs

A 65-year-old male prisoner goes on a hunger strike to protest the conditions of his detainment. After 5 days without food, he suffers a seizure for which he is taken into a medical facility. On physical examination, he looks pale and diaphoretic. His blood glucose level is 50 mg/dL. In order to keep a constant supply of energy to his brain, which of the following molecules is his liver releasing into the bloodstream?

A 17-year-old girl is brought in by her mother due to rapid weight loss over the past month. The patient says she has been having episodes of diarrhea, which she attributes to laxatives she takes regularly to keep her weight down. She also says she has not had her period yet. The patient’s mother adds that the patient has been underperforming at school and acting very strangely at home. Her current BMI is 16.8 kg/m2. On physical examination, the skin on her limbs and around her neck is inflamed and erythematous. Her tongue is bright red and smooth. She states that over the last 2 weeks, she has been eating nothing but small portions of fruit. She is diagnosed with a vitamin deficiency. Which of the following statements is true about the vitamin most likely deficient in this patient?

A 7-month-old boy is brought in to his pediatrician’s office due to concern for recurrent infections. The parents state that over the last 3-4 months, the boy has had multiple viral respiratory infections, along with a fungal pneumonia requiring hospitalization. Currently he is without complaints; however, the parents are concerned that he continues to have loose stools and is falling off of his growth curve. Newborn screening is not recorded in the patient’s chart. On exam, the patient’s temperature is 98.4°F (36.9°C), blood pressure is 108/68 mmHg, pulse is 90/min, and respirations are 12/min. The patient is engaging appropriately and is able to grasp, sit, and is beginning to crawl. However, the patient is at the 20th percentile for length and weight, when he was previously at the 50th percentile at 3 months of age. Further screening suggests that the patient has an autosomal recessive immunodeficiency associated with absent T-cells. Which of the following is also associated with this disease?

A 32-year-old woman is brought to the emergency department after she started convulsing in the office. She has no previous history of seizures and recovers by the time she arrives at the emergency department. She says that over the last 2 days she has also experienced insomnia, abdominal pain, and dark urine. Her past medical history is significant for asthma; however, she says that she has not experienced any of these symptoms previously. She smokes 1 pack of cigarettes per day, drinks a glass of wine with dinner every night, and is currently taking oral contraceptive pills (OCPs). On presentation, her temperature is 99°F (37.2°C), blood pressure is 140/98 mmHg, pulse is 112/min, and respirations are 11/min. Which of the following enzymes is most likely to be defective in this patient?

An 85-year-old woman presents to her physician with complaints of significant weakness and weight loss. She recently has been diagnosed with stage IV breast cancer for which she currently is receiving treatment. She mentions that, despite taking a diet rich in protein and calories, she continues to lose weight. On physical examination, her vital signs are stable, but muscle wasting is clearly evident in her upper limbs, lower limbs, and face. The physician explains to her that her advanced cancer is the most important cause for the weight loss and muscle wasting. This cachexia is mediated by the proteolysis-inducing factor released from cancer cells. Which of the following effects is produced by this factor?

A 32-year-old African American man presents to the office for a routine examination. He has no complaints at this time. Records show that his systolic blood pressure was in the 130–138 range and diastolic blood pressure in the 88–95 range despite counseling on lifestyle modification. He admits that he was not compliant with this advice. He takes no medications and works at home as a web designer. He does not drink alcohol but smokes marijuana on a weekly basis. Temperature is 37°C (98.6°F), blood pressure is 138/90 mm Hg, pulse is 76/min, and respirations are 12/min. BMI is 29.8 kg/m2. Physical examination is normal except for truncal obesity, with a waist circumference of 44 inches. Fasting laboratory results are as follows: Blood glucose 117 mg/dL Total cholesterol 210 mg/dL LDL cholesterol 120 mg/dL HDL cholesterol 38 mg/dL Triglycerides 240 mg/dL Which of the following mechanisms contribute to this patient’s condition?

A 30-year-old woman was found lying down and unresponsive by her parents 2 hours ago. She has no significant medical history. Two years ago, the woman discovered that her husband of 8 years was having an extramarital affair; this revelation subsequently resulted in a drawn-out divorce. After the separation, she moved back in with her parents, who note that she stays in her room, sleeps a lot, and rarely eats. A physical exam shows obtundation. Her temperature is 37.1ºC (98.7ºF), pulse is 110/min, respirations are 24/min, and blood pressure is 126/78 mm Hg. The patient’s admission labs are as follows: TSH 3.2 µU/mL Morning cortisol 8 µg/dL Prolactin 15 ng/mL FSH 7 mIU/mL LH 6 mIU/mL Glucose 22 mg/dL C-peptide not detected Beta-hydroxybutyrate ≤ 2.7 mmol/L Which of the following is most true of the cell type that is likely involved in the production of the molecule causing this patient’s symptoms?

A 4-year-old boy presents to the ophthalmologist for a down- and inward dislocation of the lens in his left eye. On physical exam, the boy has a marfanoid habitus and intellectual disability. Biochemical tests were performed to locate the exact defect in this boy. It was found that there was a significant deficiency in cystathionine beta-synthase activity with elevated homocysteine levels. Which of the following is the diagnosis?

A 3-week-old boy is brought to the physician for the evaluation of poor feeding and recurrent episodes of vomiting. He was delivered at term after an uncomplicated pregnancy. He is at the 5th percentile for length and weight. Physical examination shows generalized hypotonia. Urinalysis shows increased propionic acid concentration. The finding on urinalysis is best explained by the breakdown of which of the following substances?

An investigator is studying the changes that occur in the oxygen-hemoglobin dissociation curve of different types of hemoglobin under various conditions. The blood obtained from a male infant shows decreased affinity for 2,3-bisphosphoglyceric acid. Which of the following is the most likely composition of the hemoglobin molecule in this sample?