practice 13

1. The adult years are difficult to divide into discrete periods because biological aging does not begin until middle adulthood

2. The "wear-and-tear" theory of aging receives some support from kinship studies indicating that longevity is a family trait

3. According to the "random events" theory of aging, DNA in cells is gradually damaged through spontaneous or externally caused mutations

4. In the chemistry of aging, a "free radical" is a type of protein fiber that makes up the body's connective tissue

5. Free radicals are thought to be involved in disorders of aging

6. Persistent psychological stress is linked to telomere shortness

7. When adults make positive lifestyle changes, telomeres decrease in number

8. In adults, a gradual drop in growth hormone is associated with loss of body fat

9. Decreased vigor of the immune system seems to be caused by a breakdown of connective tissue

10. Physical changes in early adulthood are usually so gradual that most are hardly noticeable

11. Sex hormones may heighten the effects of a high-fat diet

12. The most commonly abused substances in the U.S. are cigarettes and alcohol

13. Creativity is adulthood is a function of "career age" rather than "chronological age"

14. Creative thinkers often have a limited range of interests

15. Young people's vocational aspirations correlate strongly with their parent's jobs