Nucleic Acids

Nucleic Acids is topic 1.6 of AP Biology, inside Chemistry of Life. This page works through three real practice questions on it, with the full reasoning behind each credited answer.

Practise this topic freeThe whole unit
27 questionsConcept Explanation59% with a figure
Worked examples

Three real nucleic acids questions

From the practice pool, not the mock papers — each with the reasoning that produces the answer.

59% of them come with a figure. Reading the graph or diagram correctly is most of the work here before any content knowledge applies.

81% test a single AP skill: Concept Explanation. That makes this topic unusually predictable to prepare for.

Concept Explanation

Which statement correctly compares DNA and RNA?

  1. AThe sugar differs between DNA and RNAcorrect
  2. BDNA contains amino acids, while RNA contains fatty acids.
  3. CDNA is made only of glucose monomers.
  4. DRNA cannot contain nitrogenous bases.
Why A is correct

DNA nucleotides contain deoxyribose sugar, while RNA nucleotides contain ribose sugar.

The stem asks students to explain a specific mechanism, not just recall a unit term: "Which statement correctly compares DNA and RNA". The correct choice is supported by DNA nucleotides contain deoxyribose sugar, while RNA nucleotides contain ribose sugar. The tempting alternatives such as DNA contains amino acids, while RNA contains fatty acids or DNA is made only of glucose monomers fail because they do not produce the same outcome described in the stem.

Concept Explanation

Which components are found in a DNA nucleotide?

  1. AA glucose monomer joined to a second glucose monomer
  2. BAn amino group, carboxyl group, and variable R group
  3. CA phosphate group, deoxyribose sugar, and nitrogenous basecorrect
  4. DA glycerol molecule, three fatty acids, and a phosphate group
Why C is correct

A DNA nucleotide is made of a phosphate group, deoxyribose sugar, and one nitrogenous base.

The stem asks students to explain a specific mechanism, not just recall a unit term: "Which components are found in a DNA nucleotide". The correct choice is supported by A DNA nucleotide is made of a phosphate group, deoxyribose sugar, and one nitrogenous base. The tempting alternatives such as glucose monomer joined to a second glucose monomer or amino group, carboxyl group, and variable R group fail because they do not produce the same outcome described in the stem.

Concept Explanation

RNA contains ribose sugars with a 2-prime hydroxyl group, while DNA contains deoxyribose. Which statement best connects this chemical difference to nucleic acid function?

  1. AThe 2-prime hydroxyl means RNA has no sugar-phosphate backbone.
  2. BThe 2-prime hydroxyl changes RNA into a protein made of amino acids.
  3. CThe 2-prime hydroxyl can increase RNA reactivity and reduce stabilitycorrect
  4. DThe 2-prime hydroxyl prevents RNA bases from forming any hydrogen bonds.
Why C is correct

RNA ribose includes a 2-prime hydroxyl group that can increase chemical reactivity compared with DNA's deoxyribose. This difference contributes to RNA often being less stable than DNA.

The stem asks students to explain a specific mechanism, not just recall a unit term: "RNA contains ribose sugars with a 2-prime hydroxyl group, while DNA contains deoxyribose. Which statement best...". The correct choice is supported by RNA ribose includes a 2-prime hydroxyl group that can increase chemical reactivity compared with DNA's deoxyribose. The tempting alternatives such as 2-prime hydroxyl means RNA has no sugar-phosphate backbone or 2-prime hydroxyl changes RNA into a protein made of amino acids fail because they do not produce the same outcome described in the stem.

27 questions on this topic, free to start.

Ten a day at no cost. One account covers SAT, ACT and AP.

Start free
Last reviewed 2026-08-28. Topic and unit names follow the College Board course framework. Question counts describe the PrepScore practice bank, not the exam.
Same unit
Properties of Biological Macromolecules71 questionsStructure and Function of Biological Macromolecules23 questions

Work nucleic acids until the reasoning is automatic.

Real AP questions with a full explanation on every answer, and a mistake bank that only clears when you get it right.

Start freeBack to the unit