Nucleotides help form the backbone of DNA and RNA.
Nucleotides are subunits that are linked to form nucleic acids. All nucleotides are composed of three parts: a five carbon sugar, a phosphate and a nitrogen - rich structure called a nitrogenous base.
It is the phosphate group that that makes the nucleotide so critical in DNA structure. By linking the phosphate of one nucleotide to carbon 3 of the sugar in the neighboring nucleotide, a DNA polymer is made. The repeating pattern of phosphate, sugar, then phosphate again is commonly referred to as the backbone of the DNA or RNA molecule.
The correct answer is: a. A field dominated by annual herbaceous plants.
This is because annual herbaceous plants (plants that have no persistent woody stem) die completely at the end of the growing season or after they have flowered and fruited. They will then grow again from seed.