The first three are the same as those found in DNA, but in RNA thymine is replaced by uracil as the base complementary to adenine. This base is also a pyrimidine and is very similar to thymine. Uracil is energetically less expensive to produce than thymine, which may account for its use in RNA.
Remember the definition of Osmosis; Water travels through a semipermeable membrane to an area of higher to lower concentration. Since the concentration of a solute is higher outside, we can make the assumption that water concentration is lower, and so the cell is going to release water to balance out and equalize the solution and it's surroundings.
Answer:
Fracking can contaminate water supplies if it is not done properly, because the fracking fluid injected into rock to enable gas to be released often contains chemicals. If the borehole is not properly cased to stop leaks, the fracking water can escape into the aquifer
