Two objects, A and B, are 10 m apart. Objects C and D are 20 m apart. The gravitational attraction between objects C and D is greater than the attraction between objects A and B. Explain the reason for the difference in gravitational attraction.

Which type of organism is missing from the food web seen in the illustration? primary consumers decomposers primary producers secondary consumers

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

Physical characteristics of down syndrome