Which of the following nutrients is essential for generating ATP within mitochondria?

The correct answer is that oxygen is essential for generating ATP within mitochondria. In cellular respiration, oxygen plays a crucial role as the final electron acceptor in the electron transport chain, which is a key part of aerobic metabolism. When glucose or fatty acids are metabolized, high-energy electrons are transferred through a series of protein complexes in the inner mitochondrial membrane. This process ultimately leads to the production of ATP.

Although glucose and fatty acids are important sources of fuel for generating ATP, they are not strictly essential in the sense of being required for the process of ATP generation; instead, they serve as substrates that are broken down to produce the starting materials for the electron transport chain. Without oxygen, this chain cannot function effectively, leading to a significant decrease in ATP production through aerobic pathways. Therefore, oxygen is critical for the efficiency of ATP synthesis in the mitochondria.