They are thus known as the "supporting cells" of the nervous system. The four main functions of glial cells are: to surround neurons and hold them in place, to supply nutrients and oxygen to neurons, to insulate one neuron from another, and to destroy and remove the carcasses of dead neurons (clean up).
Well there's Water, Earth, Fire, and Air. Not quite sure how this would be a school question. But here it is.
Birds and reptiles lay amniotic eggs. They consist of a shell, embryonic membranes, and the embryo.
The atmosphere is divided into different regions, called layers. The layer closest to the surface is known as troposphere, after which comes the stratosphere. The stratosphere begins at an altitude of 10 miles above the surface of the earth and stretches up to 31 miles above the surface of the earth. It is the second layer of the atmosphere (beginning from the surface of the earth) and it is the region which contains ozone, which plays a vital role in stopping ultraviolet radiation from reaching the earth's surface.
