The final electron acceptor of cellular respiration is _.
a. oxygen
b. FADH2
c. CO2
d. water
e. NADH
The Correct Answer and Explanation is :
The correct answer is a. oxygen.
Explanation:
Cellular respiration is a metabolic process through which cells convert nutrients into energy, primarily in the form of adenosine triphosphate (ATP). This process occurs in several stages: glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation (which includes the electron transport chain). The final stage, oxidative phosphorylation, is where oxygen plays a crucial role.
During glycolysis, glucose is broken down into pyruvate, producing a small amount of ATP and reducing equivalents in the form of NADH. Pyruvate then enters the mitochondria, where it is further oxidized in the citric acid cycle, producing more NADH and another electron carrier, FADH2. Both NADH and FADH2 carry high-energy electrons to the electron transport chain, which is embedded in the inner mitochondrial membrane.
As electrons move through the electron transport chain, they pass through a series of protein complexes (Complex I to IV) and coenzymes. This movement of electrons generates a proton gradient across the inner mitochondrial membrane, driving the synthesis of ATP through ATP synthase. However, for this chain of reactions to continue, the electrons need to be transferred to a final electron acceptor.
Oxygen serves as the ultimate electron acceptor in this process. At the end of the electron transport chain, oxygen combines with the low-energy electrons and protons (H+) to form water (H2O). This reaction is critical because it prevents the backup of electrons in the chain, which would halt ATP production and ultimately lead to cell death. Without oxygen, the entire process of aerobic respiration would come to a standstill, and cells would be forced to rely on anaerobic processes, which yield far less ATP. Thus, oxygen is essential for efficient ATP production in aerobic organisms.