In a tropical rain forest the tall trees block the light from reaching the small plants growing under the canopy. Describe the structural adaptations of such plants for seeking out light.

Patricia is told by her physician that her body and brain chemistry have physically adapted to the drug and that she has become dependent on the tranquilizers prescribed for her by another doctor.

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

Which of the following particles always has a positive charge? a. electronb. neutron c. proton d. ion