Final answer:
The statement in question about free radicals being capable of altering DNA and destabilizing cell membranes is actually true, as free radicals are reactive chemicals that cause oxidative stress, leading to cellular damage, and are factors in aging and various diseases.
Step-by-step explanation:
The statement about free radicals that is NOT true is that 'High levels of free radicals alter DNA and destabilize membranes.' This assertion is actually a factual statement about the nature of free radicals. Free radicals are highly reactive chemicals, such as hydroxyl ions (OH-), which can damage cellular components like DNA, leading to mutations, and can destabilize membranes by reacting with the lipids in cellular membranes.
This oxidative stress can contribute to various diseases, including cancer and cardiovascular disease. Sources of excessive amounts of free radicals include environmental pollutants, alcohol consumption, intake of trans fats, and smoking tobacco. Furthermore, free radicals play a role in immune responses and signaling processes but in excess can lead to cellular damage or cell death. Additionally, UV-A light exposure can create free radicals that contribute to indirect DNA damage. In the context of aging, the free radical theory posits that oxidative damage accrued over time contributes to the physiological effects of aging and age-related diseases.