What is the atmosphere ?
a. the semi solid layer of the earth in which convection currents move the plates
b. the water layer on the surface of the earth
c. the solid layer on the outside of the earth that moves
d. the layer of gases that surrounds the earth

Depending on the organism the number of in a cell may change

Which set of characteristics best describes sedimentary rock? a) largest type of rock, made of organic matter, hardest type of rock b) often contains layers, forms near sources of water, contains fossils c) least abundant type of rock, made of other rocks, made mostly of minerals d) most abundant type in earth's crust, made of magma/lava, contains no fossils

What causes darkening of the skin as melanin production increases