a) The biosphere is the sum of all ecosystem. It is the layer of earth where life exists.
b) The lithosphere is the outer part of the earth, consisting of the crust and upper mantle.
c) The atmosphere is the layer of gases which surrounds the earth.
d) The water present on earth in form of lakes, oceans, rivers, etc is called hydrosphere. About 2/3rd (71%)of earth's crust is covered by water. water also exists in form of water vapour in the air. The water is recycled from the surface of the earth to the atmosphere and back to the earth surface by the process of the water cycle. It supports the life across the earth.