Question

which correctly shows the order of steps in aerobic cellular respiration? image of three different flowcharts showing different orders of glycolysis, citric acid cycle, pyruvic acid → acetyl - coa, electron transport chain

Explanation:

To determine the correct order of aerobic cellular respiration, we recall the steps:

1. Glycolysis: Breaks down glucose into pyruvic acid.
2. Pyruvic acid → Acetyl - CoA: Pyruvic acid is converted to acetyl - CoA (preparatory step for the citric acid cycle).
3. Citric acid cycle (Krebs cycle): Oxidizes acetyl - CoA to produce energy - carrying molecules.
4. Electron transport chain: Uses the energy - carrying molecules from the previous steps to generate a large amount of ATP.

Now let's analyze the options:

• The first option (top - most) has the order: Glycolysis → Citric acid cycle → Pyruvic acid → Acetyl - CoA → Electron transport chain. This is incorrect because the citric acid cycle comes after the conversion of pyruvic acid to acetyl - CoA.
• The second option (middle) has the order: Glycolysis → Pyruvic acid → Acetyl - CoA → Citric acid cycle → Electron transport chain. This follows the correct sequence of aerobic cellular respiration.
• The third option (bottom - most) has an incorrect order as it places the electron transport chain before the citric acid cycle and misorders the pyruvic acid to acetyl - CoA step.

Answer:

The middle option (with the order Glycolysis → Pyruvic acid → Acetyl - CoA → Citric acid cycle → Electron transport chain)