What toxic products are produced by oxygen once it is utilized?

The correct response identifies reactive oxygen species (ROS) that are produced as toxic byproducts during the utilization of oxygen in biological systems. When oxygen is consumed during cellular respiration or metabolic processes, it can lead to the formation of several harmful products:

O2- (superoxide anion) is generated when molecular oxygen (O2) gains an extra electron. This species is highly reactive and can damage cellular components.

H2O2 (hydrogen peroxide) can form as a byproduct of various metabolic reactions, particularly in the presence of superoxide, and can further decompose into more reactive hydroxyl radicals (OH-) through numerous biochemical reactions. Both hydrogen peroxide and hydroxyl radicals are known to contribute to oxidative stress, which can damage DNA, proteins, and lipids in cells.

The presence of these toxic products emphasizes the importance of antioxidant systems that organisms have evolved to mitigate oxidative damage. The other options refer to products that do not align with the oxidative metabolism processes related to oxygen utilization. For example, carbon dioxide (CO2) and water (H2O) are typical end products of respiration and not considered toxic in the same context.