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.
These convection currents are responsible for the  movement of Earth's tectonic plates. The depth of the asthenosphere  averages somewhere between 100 km and 200km with depths up to 410  km.   Transition Zone: The depth of the transition zone is  between 410 km and 660 km.