| A | B |
|---|
| Developmental Psychologists | A branch of Psychology that studies physical, cognitive, and social change throughout the life span |
| Chromosomes | Threadlike structures made of DNA molecules that contain the genes |
| DNA (deoxyribonucleic acid) | A complex molecule containing the genetic information that makes up the chromosomes |
| X Chromosome | The sex chromosomes found in both men and women |
| Y Chromosome | The sex chromosome found only in males |
| Testosterone | The most important of the male sex hormones |
| Zygote | The fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo |
| Embryo | The developing human organism from about 2 weeks after fertilization through the second month |
| Fetus | The developing human orgainism from 9 weeks after conception to birth |
