My Answer:
Because the closing of the Purine ring is used to conserve energy all throughout. Purine biosynthesis is a process used to destroy and break down waste without wasting as much energy as some other biological processes.

Answer:
Three things that rely on the sun for energy is coal,oil, and natural gases
Explanation:
We use engery too cook our food that's an example of how gases are used.
We run our cars .Cars use oil.
And we use electricity for lights. You need coal for the electricity
To determine whether a compound is polar or nonpolar you have to take into account:
1) formation of dipoles due to the difference in electronegativities of the atoms
2) shape of the molecule to conclude whether there is a net dipole momentum.
You already, likely, know that the electronegativities of H and O are significatively different, being O more electronegative thatn H. So, you can conclude easilty that the electrons are atracted more by O than by H, thus creating two dipoles H→O
Regarding the shape, it may appear that the molecule is symmetrical, which would lead to the cancellation of the two dipoles. But that is not the true. The H2O2 is not symmetrical.
The lewis structure just show this shape
** **
H - O - O - H
** **
which is what may induce to think that the molecule is symmetrical, leading to the misconception that it is nonpolar.
But in a three dimensional arrangement you could see that the hydrogens are placed in non symmetrical positions, which leads to the formation of a net dipole momentum, and thus to a polar molecule.
The fact that H2O2 is a polar compound is the reason why it can be mixed with water and the H2O2 that you buy in the pharmacy is normally a solution in water.
So, the hydrogen peroxide is polar because the hydrogens are not placed symmetrically in the molecule, which result in a net dipole momentum.
The correct answer is option B.
The hematite particles rearrange to form a new substance. This is an example of a chemical change.
A chemical change is an irreversible process wherein the atoms of a substance undergoes a rearrangement that causes it to from a new substance with unique chemical properties.