32. During DNA replication of an eukaryotic cell, a guanine (G) is mistakenly paired with a thymine (T) and escapes the initial proofreading by DNA polymerase. This G-T pair becomes fully incorporated into the double helix. Which of the following best describes how the cell corrects this mismatch/error? (A) The cell utilizes DNA photolyase to break the hydrogen bonds between the mismatched bases and flip them into the correct orientation. (B) The cell utilizes specific endonucleases to recognize the helical distortion and identify the newly synthesized strand to cut out the segment containing the incorrect nucleotide. (C) The cell utilizes RNA primase to recognize the mismatched sites, where it initiates reverse transcription to replace the DNA segment with a temporary RNA patch. (D) The cell utilizes DNA ligase to identify the incorrect hydrogen bonding site and uses its 5' to 3' exonuclease activity to chew back the faulty nucleotide. (E) The cell utilizes a multi-protein complex to scan the DNA for bulky lesions and remove a 12-30 nucleotide oligomer of the damaged strand.

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.

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