Which process in eukaryotic cells will proceed normally whether oxygen (\(\mathrm{O_2}\)) is present or absent?

• A. Oxidative phosphorylation
• B. Glycolysis
• C. Electron transport chain
• D. Citric acid cycle (Krebs cycle)

Answer: (B)

Verified step by step guidance

1. Understand the context: Cellular respiration in eukaryotic cells involves multiple processes, some of which require oxygen (\(\mathrm{O_2}\)) and others that do not. The goal is to identify the process that can occur regardless of oxygen availability.
2. Review the processes listed: Oxidative phosphorylation, the electron transport chain, and the citric acid cycle (Krebs cycle) are all dependent on oxygen (\(\mathrm{O_2}\)) to function properly. These processes are part of aerobic respiration.
3. Focus on glycolysis: Glycolysis is the first step in cellular respiration and occurs in the cytoplasm. It does not require oxygen (\(\mathrm{O_2}\)) and can proceed under both aerobic and anaerobic conditions.
4. Explain why glycolysis is independent of oxygen: During glycolysis, glucose is broken down into two molecules of pyruvate, producing a small amount of ATP and NADH. If oxygen is absent, the pyruvate can undergo fermentation to regenerate NAD+, allowing glycolysis to continue.
5. Conclude: Glycolysis is the correct answer because it is the only process listed that can proceed normally whether oxygen (\(\mathrm{O_2}\)) is present or absent.