What are the two strands of dna held together by?

Which statement is true about the cell theory? a) it is well-supported by evidence. b) it is unchangeable and permanent.

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

Aplant may open end close its stomata to prevent excess water loss and maintain