A 6-month-old infant is brought to the pediatric clinic for a routine check-up. The parents report that the child has a musty body odor and feeding difficulties. A newborn screening test revealed elevated levels of a specific amino acid in the blood. The physician diagnoses an inborn error of metabolism and recommends dietary modifications to prevent cognitive impairment. Which of the following amino acids should be restricted in this patient’s diet?
A 30-year-old male athlete presents to the clinic complaining of fatigue and muscle weakness despite following an intense weightlifting routine and consuming a high-protein diet supplemented with branched-chain amino acids (BCAAs). His blood tests reveal elevated insulin resistance and mildly increased fasting blood glucose levels. Which of the following amino acids is most likely contributing to his metabolic disturbance?
Which of the following correctly describes the role of D-amino acids and L-α-amino acids in biological systems?
A researcher is studying a reaction in which a water molecule is released during the formation of a new covalent bond between two amino acids. This reaction is crucial for the synthesis of all proteins in living organisms. Which bond is formed during this reaction?
Which of the following statements correctly describes the relationship between pH and hydrogen ion concentration [H+]?
Which of the following mechanisms primarily helps maintain the pH of extracellular fluid within the normal range of 7.35 to 7.45?
A 58-year-old man with chronic obstructive pulmonary disease (COPD) presents with shortness of breath, confusion, and drowsiness. Arterial blood gas (ABG) analysis reveals: pH = 7.28 (acidic) PaCO₂ = 55 mmHg (elevated) HCO₃⁻ = 24 mEq/L (normal) The physician explains that water is critical for acid-base homeostasis, as it participates in buffering systems that regulate blood pH. Which of the following best describes water’s role in acid-base balance?
A 67-year-old woman with chronic kidney disease presents with confusion, nausea, and muscle weakness. Lab tests reveal severe hyperkalemia (K⁺ = 7.2 mEq/L). The doctor explains that water is a universal solvent, allowing for the transport and distribution of electrolytes, but in kidney disease, electrolyte imbalances can occur due to impaired filtration. Which property of water makes it an excellent solvent for electrolytes like potassium (K⁺) and sodium (Na⁺)?
A 25-year-old marathon runner collapses at the finish line after completing a race in hot and humid weather. He is disoriented, has dry skin, and a body temperature of 40°C (104°F). His pulse is rapid, and his blood pressure is low. His lab results show elevated serum sodium levels, suggesting dehydration. The physician explains that water plays a critical role in body temperature regulation, but in this case, the body’s ability to dissipate heat has been overwhelmed. Which of the following properties of water is most important for thermoregulation through sweating?
