Question

A nucleoside differs from a nucleotide in the absence of ______.

Options

• base

• sugar

• phosphate group

• hydroxyl group

Answer 1

A nucleoside differs from a nucleotide in the absence of phosphate group.

Explanation:

A nucleoside is a basic molecular building block composed of only two parts: a nitrogenous base and a five-carbon sugar (either ribose or deoxyribose). A nucleotide, on the other hand, is a more complex structure that contains these same two components plus an additional phosphate group attached to the sugar. Therefore, the primary chemical difference between the two is that a nucleoside lacks the phosphate group; once a phosphate is chemically bonded to a nucleoside, it becomes a complete nucleotide, which can then be linked with others to form DNA or RNA.