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Multiple Choice
Which of the following best explains why the four stages of cellular respiration do not function independently?
A
Each stage relies on the products of the previous stage to proceed.
B
Each stage uses completely different enzymes and substrates.
C
All stages occur simultaneously in the same cellular compartment.
D
The stages are regulated by unrelated signaling pathways.
Verified step by step guidance
1
Understand the context of cellular respiration: Cellular respiration is a multi-step process that cells use to convert glucose into energy in the form of ATP. The four stages are glycolysis, pyruvate oxidation, the citric acid cycle (Krebs cycle), and oxidative phosphorylation.
Recognize the interdependence of the stages: Each stage produces specific molecules (e.g., NADH, FADH2, ATP, or intermediates) that are required for the subsequent stage to proceed. For example, glycolysis produces pyruvate, which is essential for pyruvate oxidation.
Analyze the role of products in each stage: Glycolysis generates NADH and ATP, which are used in later stages. Pyruvate oxidation produces acetyl-CoA, which enters the citric acid cycle. The citric acid cycle generates NADH and FADH2, which are crucial for oxidative phosphorylation.
Eliminate incorrect options: The stages do not use completely unrelated enzymes and substrates, as many are interconnected. Not all stages occur in the same cellular compartment (e.g., glycolysis occurs in the cytoplasm, while the citric acid cycle and oxidative phosphorylation occur in the mitochondria). The stages are not regulated by unrelated signaling pathways but are instead tightly coordinated.
Conclude that the correct explanation is that each stage relies on the products of the previous stage to proceed, highlighting the sequential and interdependent nature of cellular respiration.