The following test results were obtained: urine flow rate = 2.0 ml/min; urine inulin concentration = 60 mg/ml; plasma inulin concentration = 2 mg/ml; urine potassium concentration = 20 μmol/ml; plasma potassium concentration = 4.0 μmol/ml; urine osmolarity = 150 mOsm/L; and plasma osmolarity = 300 mOsm/L. What is the free water clearance rate?

#Question id: 527

#Unit 1. Molecules and their Interaction Relevant to Biology

What chemical species activates the GLUT4 protein to transport glucose into cells?

#Question id: 528

#Unit 1. Molecules and their Interaction Relevant to Biology

Once inside a cell, glucose is rapidly phosphorylated to glucose-6-phosphate. What is the main purpose of this phosphorylation?

#Question id: 529

#Unit 1. Molecules and their Interaction Relevant to Biology

When a muscle is stimulated to contract aerobically, less lactic acid is formed than when it contracts anaerobically because:

#Question id: 531

#Unit 1. Molecules and their Interaction Relevant to Biology

Glucose labeled with ¹⁴C in C-1 and C-6 gives rise in glycolysis to pyruvate labeled in:

#Question id: 532

#Unit 1. Molecules and their Interaction Relevant to Biology

In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard free-energy change (DG'°) of 23.8 kJ/mol.  Under what conditions (encountered in a normal cell) will the free-energy change (DG) be negative, enabling the reaction to proceed to the right?

#Question id: 533

#Unit 1. Molecules and their Interaction Relevant to Biology

Glucose, labeled with 14C in different carbon atoms, is added to a crude extract of a tissue rich in the enzymes of the pentose phosphate pathway.  The most rapid production of 14CO2 will occur when the glucose is labeled in: