Which chromosomes do NOT contain the genes that affect sexual characteristics?

According to your text, the impact of social class on longevity results PRIMARILY from

a. different access to goods and services, especially medical care b. differences in the willingness of individuals to follow doctor's instructions c. generational differences in the impact of epigenetic factors d. differences in the use of alcohol, tobacco and other drugs

Developmental psychologist Dr. Wiggles is interested in preschool children's helping behavior. He spends hours watching children at the campus preschool, taking great care not to interfere with the children or to influence their behavior in any way. What data collection technique is Dr. Wiggles using?

a. Case study b. Naturalistic observation c. Meta-analysis d. Structured observation