1. You probably already know that some traits are genetic and others are environmental. But most human traits reflect an interaction between genetic and environmental factors. Name some traits that might fall into this category, and explain why you think they do. 2. Describe are some benefits of human genetic variation? What are some potential problems it can cause?

cancer   is   essentially   uncontrolled   mitosis   of specialized cells

. the sierra madre fault zone of southern california

. the san andreas fault california

imagine a line passing through the center of earth that goes through both the north pole and the south pole. this imaginary line is called an axis. earth spins around its axis, just as a top spins around its spindle. this spinning movement is called earth's rotation. at the same time that the earth spins on its axis, it also orbits, or revolves around the sun. this movement is called revolution.