87. A researcher is purifying a 150 kDa protein complex using size-exclusion chromatography. The column is calibrated with standard proteins: thyroglobulin (669 kDa), ferritin (440 kDa), aldolase (158 kDa), and ovalbumin (44 kDa). The void volume (Vo) is 8 mL and the total column volume (Vt) is 24 mL. If the target complex elutes at 14 mL, which statement is correct? (A) The complex is eluted near the Vo, indicating it is larger than 669 kDa. (B) The complex elutes at a volume consistent with its 150 kDa mass, confirming it is in its monomeric/native form. (C) The complex elutes later than ovalbumin (44 kDa), suggesting it is a small peptide. (D) The complex is completely excluded, meaning it is larger than the pore size of the gel. (E) The elution at 14 mL indicates the column is packed incorrectly.

13. Suppose a person begins breathing very rapidly while resting (hyperventilating), which of the following best describes how homeostasis is restored? (A) Rapid breathing decreases blood CO2 levels, thereby raising blood pH. The frontal cortex detects the change and reduces stimulation of the rib muscles and the diaphragm, thereby decreasing the breathing rate. (B) Rapid breathing increases blood CO2 levels, thereby causing the blood pH to drop. The hypothalamus detects the change and decreases stimulation of the rib muscles and the diaphragm, thereby reducing the breathing rate. (C) Rapid breathing decreases blood CO2 levels, thereby raising blood pH. The hypothalamus detects the change and reduces stimulation of the rib muscles and the diaphragm, thereby decreasing the breathing rate. (D) Rapid breathing increases blood CO2 levels, thereby causing the blood pH to drop. The medulla oblongata detects the change and reduces stimulation of the rib muscles and the diaphragm, thereby decreasing the breathing rate. (E) Rapid breathing decreases blood CO2 levels, thereby raising blood pH. The medulla oblongata detects the change and reduces stimulation of the rib muscles and the diaphragm, thereby decreasing the breathing rate.

相關試題

相關試卷