Question

cellular respiration overview
the outcomes of the five stages of cellular respiration — glycolysis, pyruvate processing, the citric acid cycle, the electron transport chain (etc), and atp synthase — can be summarized as follows

1. the carbon atoms in glucose become fully oxidized to co₂
2. most of the chemical energy in glucose — meaning, energy that is based on the position of electrons in c - c and c - h bonds — is transferred to electrons in the bonds in nadh and fadh₂ a small amount is transferred directly to atp during glycolysis and the citric acid cycle.
3. when electrons from nadh and fadh₂ flow through the etc, chemical energy in the electron carriers is released. this energy powers etc proteins that pump protons across the inner mitochondrial membrane, establishing a strong concentration and charge gradient.
4. protons move down their concentration gradient through atp synthase. this machine transforms the flow of positive charge into mechanical energy (spinning) that catalyzes the synthesis of atp from adp and phosphate ions. 90% of the atp produced by cellular respiration results from the etc and atp synthase.
5. in plants, humans and nearly all other animals, most fungi, and many other organisms, oxygen acts as the final electron acceptor at the end of the etc, with water being released as a product.

when oxygen acts as the final electron acceptor in the etc, it is reduced. stated another way, the following is a redox reaction.
o₂ + 4e⁻ + 4h⁺ → 2h₂o
true
false

Explanation:

In the electron transport chain (ETC), oxygen (\(O_2\)) acts as the final electron acceptor. In the given reaction \(O_2 + 4e^-+4H^+\to2H_2O\), oxygen gains electrons (\(e^-\)) and hydrogen ions (\(H^+\)). Reduction is defined as the gain of electrons. Here, \(O_2\) is going from an oxidation state of \(0\) (in \(O_2\)) to \(- 2\) (in \(H_2O\) for each oxygen atom). So, \(O_2\) is being reduced in this redox reaction.

Answer:

True