Humber Admissions Practice Test

What is the main function of the electron transport chain?

1. To break down glucose

2. To shuttle electrons and produce ATP

3. To convert pyruvic acid to carbon dioxide

4. To synthesize DNA

The correct answer is: To shuttle electrons and produce ATP

The primary function of the electron transport chain is to shuttle electrons and produce ATP. This process takes place in the inner mitochondrial membrane and is a crucial step in cellular respiration. During this stage, high-energy electrons derived from nutrients like glucose are transferred through a series of protein complexes. As electrons move through these complexes, they release energy, which is used to pump protons across the mitochondrial membrane, creating a proton gradient. This gradient then drives the synthesis of ATP through a process called chemiosmosis, where protons flow back through an enzyme known as ATP synthase, converting ADP and inorganic phosphate into ATP. The production of ATP is vital because it serves as the energy currency of the cell, powering various biological processes. In contrast, breaking down glucose is a more comprehensive process that occurs during glycolysis and the citric acid cycle, while converting pyruvic acid to carbon dioxide is also part of cellular respiration but reflects earlier steps. The synthesis of DNA is unrelated to the electron transport chain's primary roles in energy production.