Why is the direction of phloem transport opposite in early spring and late fall? a. the temperature changes can reverse the flow in late fall b. the direction of sieve plates in the phloem sieve tube elements become opposite at different times c. the availability of water can change the bulk-flow of food in the phloem d. the source and sink are on opposite sides in early spring and late fall

Match your vocabulary word to its definition. 1. emigration 2. immigration 3. migration 4. overpopulation 5. sustainable development 6. under population 7. unsustainable development 8. urbanization the movement from one place to another the number of people exceeds the available natural resources in an area leaving one's homeland to settle in a new place the increase in the population of a city the movement of people to a new country the ability to meet current needs without reducing the ability to meet future needs resources being used up at a faster rate than they can be replenished birth rate insufficient to replace the existing population