Let's evaluate each statement regarding metabolic pathways involved in cellular respiration:
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The function of the citric acid cycle is the transfer of electrons from pyruvate to NADH to O2.
- This statement is not accurate. The citric acid cycle (also known as the Krebs cycle) primarily involves the oxidation of acetyl-CoA to produce NADH and FADH2, but it does not directly transfer electrons from pyruvate to NADH to O2. Instead, it takes place after pyruvate has been converted to acetyl-CoA, and oxygen is utilized in the electron transport chain, not directly in the citric acid cycle.
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The function of the bonding of acetic acid to the carrier molecule CoA to form acetyl CoA is the reduction of glucose to acetyl CoA.
- This statement is not accurate. The conversion of glucose to acetyl-CoA involves multiple steps, including glycolysis (which breaks down glucose into pyruvate) followed by the conversion of pyruvate to acetyl-CoA. The formation of acetyl-CoA from pyruvate does not involve the "reduction" of glucose; it is a decarboxylation process where CO2 is released, and NAD+ is reduced to NADH.
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The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.
- This statement is accurate. Glycolysis is the first step in cellular respiration and occurs in the cytoplasm, where one molecule of glucose (a six-carbon compound) is broken down into two molecules of pyruvate (a three-carbon compound). The process results in a net gain of two ATP molecules and two NADH molecules.
In conclusion, the only accurate statement is the third one: The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.
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