What bodies of water make up a river system?

If the frequency of the p allele is .63 in the population then what is the frequency of the q allele?

Which element forms the basis of all organic organisms a carbon b oxygen c hydrogen d nitrogen

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