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Multiple Choice
Which of the following processes occurs first during cellular respiration in eukaryotic cells?
A
Oxidative phosphorylation
B
Glycolysis
C
Electron transport chain
D
Krebs cycle (Citric Acid Cycle)
Verified step by step guidance
1
Understand the concept of cellular respiration: Cellular respiration is the process by which cells convert glucose into energy (ATP). It consists of several stages: glycolysis, the Krebs cycle (citric acid cycle), and oxidative phosphorylation (which includes the electron transport chain).
Identify the sequence of events: Glycolysis is the first step in cellular respiration. It occurs in the cytoplasm and does not require oxygen. The other processes, such as the Krebs cycle and oxidative phosphorylation, occur later and require the presence of oxygen.
Explain glycolysis: Glycolysis is the breakdown of glucose into two molecules of pyruvate. This process generates a small amount of ATP and NADH, which are used in later stages of cellular respiration.
Clarify the role of the Krebs cycle and oxidative phosphorylation: The Krebs cycle occurs in the mitochondria and processes pyruvate to produce more NADH and FADH2. Oxidative phosphorylation, which includes the electron transport chain, uses these molecules to generate a large amount of ATP.
Conclude the sequence: Since glycolysis is the initial step in cellular respiration, it occurs first before the Krebs cycle, electron transport chain, or oxidative phosphorylation.