Which statement correctly distinguishes a nucleoside from a nucleotide?

Which statement correctly distinguishes a nucleoside from a nucleotide?

• A. A nucleoside has three phosphates, while a nucleotide has one phosphate.
• B. A nucleoside includes phosphate groups, while a nucleotide does not.
• C. Nucleosides are built from sugars only; nucleotides include bases.
• D. Nucleosides are components of DNA backbone; nucleotides are temporary carriers of information.

Answer: (A)

The key idea is the presence of phosphate groups distinguishing a nucleoside from a nucleotide. A nucleoside is simply a sugar (deoxyribose or ribose) bonded to a nitrogenous base; it has no phosphate groups. A nucleotide adds one or more phosphate groups to that nucleoside, giving forms like monophosphate, diphosphate, or triphosphate. For example, adenosine is a nucleoside, while ATP (adenosine triphosphate) is a nucleotide used for energy transfer. That makes the statement about three phosphates versus one phosphate inaccurate, because nucleosides lack phosphate groups entirely, and nucleotides can have varying numbers of phosphates. The other options don’t fit because nucleosides aren’t built from sugars alone (they also include a base), they don’t contain phosphate groups, and nucleotides—not nucleosides—form the DNA backbone through phosphodiester bonds.

The key idea is the presence of phosphate groups distinguishing a nucleoside from a nucleotide. A nucleoside is simply a sugar (deoxyribose or ribose) bonded to a nitrogenous base; it has no phosphate groups. A nucleotide adds one or more phosphate groups to that nucleoside, giving forms like monophosphate, diphosphate, or triphosphate. For example, adenosine is a nucleoside, while ATP (adenosine triphosphate) is a nucleotide used for energy transfer.

That makes the statement about three phosphates versus one phosphate inaccurate, because nucleosides lack phosphate groups entirely, and nucleotides can have varying numbers of phosphates. The other options don’t fit because nucleosides aren’t built from sugars alone (they also include a base), they don’t contain phosphate groups, and nucleotides—not nucleosides—form the DNA backbone through phosphodiester bonds.