L2：
讲座
1. What does the professor mainly discuss?
Various ways free radicals are formed
Characteristics of various stages of aging
Whether free radicals cause aging
Whether antioxidants effectively stabilized free radicals
2. According to the professor, what do biological-clock theories propose?
That an organism’s behavior plays an important role in the aging process
That the aging process is genetically predetermined
That organisms age as the result of a gradual loss of energy
That environmental conditions can speed or slow the aging process
3. According to the free-radical theory, why does aging occur?
Antioxidants begin interfering with cell metabolism
Cells begin producing fewer free radicals
Antioxidants damage various cell structures
Unstable oxygen molecules damage cells’ DNA
4. What did the results of the fruit fly study suggest?
Insects’ cells may not produce free radicals
Some insects naturally produce-large quantities of SOD
Antioxidants can slow the rate of aging in some organisms
Various antioxidants may work together to repair cell damage
5. According to the researchers in the roundworm study, how did a calorie-restricted diet extend the roundworms’ life span?
By activating a special gene
By slowing cell metabolism
By helping process nutrients more efficiently
By increasing the rate of cell repair
6. What does the professor imply when she says this:
The theory is too complex to explain in a short time
The theory is now considered outdated
The theory has only recently gained wide acceptance
D. The theory was already discussed in a previous class
