Which statements explain the primary difference between the structure of a nucleic acid and the structure of a protein?
a. a nucleic acid has alternating base pairs. a protein has alternating peptides.
b. a nucleic acid is held together by the sugar­phosphate complex. a protein is held together by the carbon­ carbon bonds.
c. nitrogen bases form the backbone of a nucleic acid. peptides form the backbone of a protein.
d. nucleotides link together to form a nucleic acid. amino acids link together to form a protein.

explanation:

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

imagine a line passing through the center of earth that goes through both the north pole and the south pole. this imaginary line is called an axis. earth spins around its axis, just as a top spins around its spindle. this spinning movement is called earth's rotation. at the same time that the earth spins on its axis, it also orbits, or revolves around the sun. this movement is called revolution.