The test may cause momentary gagging because the back of the throat is a sensitive area, but it should not be painful. The sample your doctor collects is taken to a laboratory, where it is put on a plate that allows any bacteria on it to grow. This process is called a culture.
Often these are called transition zones which represent the start and end of a specific region and can be large or small. For example, the transition zone between Sub-Saharan Africa and North Africa is rather large because there is a mixing between the two regions. Regional geographers study this zone as well as the distinct characteristics of Sub-Saharan Africa and North Africa.
The Sahel is also a cultural transition zone separating the Arab and Muslim dominated countries of North Africa from the African and Christian (and/or animist) peoples of sub-Saharan Africa.Note how the presence of Islam tails off dramatically as one leaves the Sahel and enters sub-Saharan Africa.he East African Rift Valley System is an example of a fissure in the Earthâs crust in which the continent is splitting apart, causing an extensive series of valleys, fingerlike freshwater lakes and volcanoes to form. The map below shows how dominant savanna zones are in sub-Saharan Africa, in particular the Sahel.