NANP Board Practice Exam

The Electron Transport Chain in the mitochondria requires which element for proper functioning?

1. Carbon Dioxide

2. Hydrogen

3. Oxygen

4. Nitrogen

The correct answer is: Carbon Dioxide

The Electron Transport Chain (ETC) is a crucial component of cellular respiration that takes place in the mitochondria. It plays a vital role in producing ATP, the energy currency of the cell, through oxidative phosphorylation. One of the key elements required for the proper functioning of the ETC is oxygen. Oxygen acts as the final electron acceptor in the chain. As electrons are transferred through various protein complexes, they ultimately reach oxygen, which combines with electrons and hydrogen ions to form water. This process not only drives the generation of ATP but also prevents the backup of electrons in the chain, ensuring that the process continues smoothly. While hydrogen is a component of water and is involved in the process as protons (H+), it does not serve the same essential role in the final step of accepting electrons. Carbon dioxide is a byproduct of metabolic processes and is not used in the ETC itself, while nitrogen is not directly involved in this energy production pathway. Thus, oxygen is indeed the critical element for the proper functioning of the Electron Transport Chain.