Question

all the biological macromolecules contain hydrogen, oxygen and carbon. however, there are distinguishing features of each. which of the following could be used to differentiate between a carbohydrate and a nucleic acid?
carbohydrate molecules have a nitrogen base, whereas nucleic acid molecules have an r group.
carbohydrate molecules have nitrogen atoms, whereas nucleic acids have an attached phosphate group.
carbohydrate molecules contain only carbon, hydrogen and oxygen atoms, whereas nucleic acid molecules also have a nitrogen base and phosphate group.
carbohydrate molecules are only found in chains, while nucleic acid molecules only form rings.

Explanation:

Carbohydrates are composed of carbon, hydrogen, and oxygen only. Nucleic acids contain a nitrogen - base, a phosphate group along with carbon, hydrogen and oxygen. The first option is wrong as carbohydrates do not have a nitrogen - base. The second option is incorrect because carbohydrates don't have nitrogen atoms in the way described and nucleic acids don't have an R - group in this context. The fourth option is wrong as carbohydrates can form rings and nucleic acids can form chains.

Answer:

Carbohydrate molecules contain only carbon, hydrogen and oxygen atoms, whereas nucleic acid molecules also have a nitrogen base and phosphate group.