Certain mental problems are thought to be caused by not having enough neurotransmitters. Why would a lack of neurotransmitters cause problems?
A. Neurons would not be able to receive sensory messages.
B. Neurotransmitters send signals from neuron to neuron.
C. Neurons would not be able to grow longer.
D. Neurons would not be able to move to new areas.

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

Patient has just received an organ transplant which treatment would be most effective in preventing the patient’s body from

When new rock is added to an oceanic ridge, the magnetized strips on either side of the ridge are evidence of sea-floor spreading. this is because the rocks on the two sides of the ridge o are equal in width and in polarity are polar opposites oare magnetized vary in width but are equal in polarity