An outbreak of a disease occurs, and a scientist at the Centers for Disease Control (CDC) is in charge of determining the cause. She is studying the microorganism that is thought to be responsible for the disease. Which of the following would be
the most helpful to the scientist?
Pasteur's germ theory of disease
Koch's postulates
Redi's experiment
John Snow's map

1. emigration the movement of people from one place to another 2. immigration a situation in which resources are being used up at a faster rate than they can be replenished 3. migration the leaving of one's homeland to settle in a new place 4. overpopulation the movement of people to a new country 5. sustainable development a situation in which the birth rate is not sufficient to replace the existing population 6. underpopulation the ability to meet current needs without reducing the ability to meet future needs 7. unsustainable development the increase in the population of a city 8. urbanization a situation in which the number of people exceeds the available natural resources in an area