HUMAN PHYSIOLOGY
BREATHING AND RESPIRATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Because it happens right before the ETC which does require O2.
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Because without O2 glycolysis begins producing lactic acid and not pyruvate which is necassary for Krebs
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Because without O2 glycolysis shuts down
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Because the ETC will not produce enough NAD+ to be used in the krebs cycle if oxygen is not present.
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Detailed explanation-1: -In addition, the respiratory cycle converts NADH and FADH2 into reactants that the Krebs cycle requires to function. Thus, if oxygen is not present, the respiratory cycle cannot function, which shuts down the Krebs cycle. For this reason, the Krebs cycle is considered an aerobic pathway for energy production.
Detailed explanation-2: -Without oxygen, the electron transport chain becomes jammed with electrons. Consequently, NAD cannot be produced, thereby causing glycolysis to produce lactic acid instead of pyruvate, which is a necessary component of the Krebs Cycle. Thus, the Krebs cycle is heavily dependent on oxygen, deeming it an aerobic process.
Detailed explanation-3: -Nonavailability of these reducing powers results in entry of pyruvate in anaerobic respiration pathway. So, to maintain continuity of Kreb cycle, oxidation of NADH and FADH2 by oxygen is prerequisite and the cycle is considered aerobic.
Detailed explanation-4: -The Presence of Oxygen Glycolysis is an anaerobic process-it does not need oxygen to proceed. This process produces a minimal amount of ATP. The Krebs cycle and electron transport do need oxygen to proceed, and in the presence of oxygen, these processes produce much more ATP than glycolysis alone.
Detailed explanation-5: -The Krebs cycle, by itself, does not require the presence of oxygen; this element is necessary for the last stage of aerobic cellular respiration, i.e., oxidative phosphorylation. Organic molecules endowed with energy (carbohydrates, lipids, proteins) are split in previous reactions.