More than ___ genes have been identified that show increased activity during sleep

Unrealistic beauty ideals in magazines likely contribute to adolescent girls'

a. increased self-confidence. b. negative body image. c. early maturation. d. late maturation.

Trisomy 13, trisomy 18, and trisomy 21 are all causes of mental retardation associated with

a) prenatal infections. b) metabolic dysfunctions. c) fragile areas on the X chromosome. d) more than the normal number of chromosomes.