Answer: The additional protection in the body of aerobic organisms are that they can fight with the ROS radicle formed in the body.
Explanation:
The aerobic organism use oxygen as a final electron acceptor. The aerobic organisms have enzymes in the body which helps in getting from the reactive oxygen species. These enzymes are superoxide dismutase, peroxidase and catalase.
Anaerobes are vulnerable to these ROS which is produced by their own metabolism. They do not contain the enzymes such as superoxide dismutase and catalase that can help them to survive in these conditions.
Hence, because of antioxidants the aerobic organism can survive in oxygen and anaerobes cannot.