There are more hydrogen atoms in living organisms than any other atom, but oxygen is more abundant in terms of mass. why is this statement true?

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

Describe the function of the endomembrane system? what organelles are involved?

Which organ controls breathing? lungs alveoli heart diaphragm