Soil erosion is defined as the wearing away of topsoil. Topsoil is the top layer of soil and is the most fertile because it contains the most organic, nutrient-rich materials. Therefore, this is the layer that farmers want to protect for growing their crops and ranchers want to protect for growing grasses for their cattle to graze on.
I would say immigration only.
emigration would theoretically reduce the genetic variation as unique individuals leave, but immigration would bring unique traits into circulation in an ecosystem.
I'm not super great at biogy tho so this might not be right... :)
The substance needed for cell energy is ATP, which is short form of Adenosine Triphosphate. This is created in the mitochondria, the energy center for the cell. It is created through the process of Cellular Respiration
It's phycology, the study of the human's response to stimuli, which you are trying to find out whether or not the child can tell that they both have the same amount.
hope this helps:)
