Grant Clay Period 3 11/2/08 AP Psychology Outline Chapter 11: Human Development across Lifespan Red ? Definition Blue - Important Points Green - Important People & Contributions Development ? Sequence of Age-Related Changes that occur as a Person Progresses from Conception until Death. Prenatal Development Zygote ? 1 Celled Organism formed by Union of Sperm and an Egg. Prenatal Period ? Period from Conception to Birth, usually 9 Months of Pregnancy. Prenatal Development Germinal Stage ? First Phase of Prenatal Development, encompassing the first 2 Weeks after Conception. Placenta ? Structure that allows Oxygen & Nutrients to pass into Fetus from the Mother?s Bloodstream and Bodily Waste to Pass Out the Mother.