Chapter 8, Problem 42A

Summary Introduction

To determine:

The advantage of aerobic metabolism over anaerobic metabolism in energy production in living organisms

Introduction:

Organisms obtain energy through a process called cellular respiration. This process occurs in two stages; glycolysis and aerobic respiration. Glycolysis is an anaerobic process while aerobic respiration includes Krebs cycle and electron transport.

Answer to Problem 42A

Aerobic metabolism is a highly efficient system of producing energy in comparison to anaerobic metabolism in living organisms. Both Krebs cycle and electron transport are part of aerobic metabolism. They together produce 36 molecules of ATP (in eukaryotes) while glycolysis which is an anaerobic pathway produce only 2 molecules of ATP.

Explanation of Solution

In anaerobic metabolism, organisms only break down glucose in the cytoplasm producing only two molecules of ATP. Glucose is only broken down to pyruvate. Glycolysis is an anaerobic process as it does not require oxygen.

In aerobic metabolism, organisms break down glucose to the level of carbon dioxide. This releases more energy than anaerobic process. In Krebs cycle, two molecules of ATP are formed for each glucose molecule. The electron transport chain produces 24 ATP molecules. Together they produce 36 molecules of ATP for each glucose molecule.

Hence, aerobic metabolism is more efficient than anaerobic metabolism in energy production in living organisms.