Final answer:
The claim regarding free radicals' role in aging and cancer is true. The free radical theory asserts that cellular damage from oxidative stress contributes to aging and disease. Research has supported this theory, showing that managing oxidative stress can affect lifespan in certain organisms.
Step-by-step explanation:
The statement that many researchers believe that free radicals are responsible for the effect of aging and cancer is largely true. The free radical theory of aging posits that oxidative stress from free radicals leads to cellular damage, contributing to aging and various age-related diseases, including cancer. This theory has two main versions: one suggesting that oxidative damage causes the aging process itself and another suggesting that it causes age-related diseases. The evidence suggests that oxidative damage does play a role in the aging process. Studies have demonstrated lifespan extension in organisms like yeast, worms, and fruit flies through the reduction of oxidative damage. Conversely, increased oxidative damage has been shown to shorten lifespans in certain animal models. The role of free radicals in diseases such as cancer is noted due to their propensity to damage DNA and cells, contributing to disease pathogenesis.
Researchers are also looking at the effects of calorie restriction and its potential to increase lifespan by reducing oxidative stress, although results in primates have been inconclusive. Lastly, living organisms have defense mechanisms against free radicals, such as radical scavengers like vitamin C in the blood and vitamin E in fats, which help neutralize these toxic radicals.