Photographs of the surface of mars reveal the presence of sand dunes that shift over time. these dunes demonstrate the presence of what phenomenon on mars?
f magnetic pole reversals
g winds
h plate tectonics
j precipitation

the cost of mining is extremely low compared to the money earned from mining, creating income to improve the environment.

in a chemical reaction, the atoms and molecules produced by the reaction are called products. no new atoms are created, and no atoms are destroyed. in a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.

la transducción de señal ocurre cuando una molécula de señalización de fluido extracelular activa un receptor de superficie de la célula.