Which statements describe the movement of blood through the heart? check all that apply.
blood from the veins enters the ventricles.
atria and ventricles contract at the same time.
atria push blood into the ventricles.
valves allow for two-way blood flow.
ventricles push blood out of the heart.

Apart of an ecosystem that can restrict the growth of a population is referred to as

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 these is a provisioning service people get from the ocean