Cracking the AP Biology Exam


Molecular Genetics


Directions: Each of the questions or incomplete statements below is followed by five suggested answers or completions. Select the one that is best in each case. Answers can be found here.

1. Which of the following cellular organelles is most closely associated with the transcription activity of RNA?

(A) Mitochondrion

(B) Nucleus

(C) Ribosome

(D) Golgi apparatus

(E) Lysosome

2. The correct sequence between genes and their phenotypic expression is

(A) RNA-DNA-protein-trait

(B) DNA-RNA-protein-trait

(C) protein-DNA-RNA-trait

(D) trait-DNA-RNA-protein

(E) trait-protein-DNA-RNA

3. Which of the following substances is found in RNA molecules but not in DNA molecules?

(A) Adenine

(B) Phosphate group

(C) Thymine

(D) Deoxyribose

(E) Ribose

4. If a messenger RNA codon is UAC, which of the following would be the complementary anticodon triplet in the transfer RNA?






5. During posttranslational modification, the polypeptide from a eukaryotic cell typically undergoes substantial alteration that results in

(A) excision of introns

(B) addition of a poly(A) tail

(C) formation of peptide bonds

(D) a change in the overall conformation of a polypeptide

(E) the synthesis of amino acids

6. All of the following enzymes are involved in the replication process of DNA EXCEPT:

(A) DNA helicase

(B) DNA polymerase

(C) RNA polymerase

(D) RNA primase

(E) DNA ligase

7. Which of the following represents the maximum number of amino acids that could be incorporated into a polypeptide encoded by 21 nucleotides of messenger RNA?

(A) 3

(B) 7

(C) 21

(D) 42

(E) 63

Directions: Each group of questions consists of five lettered headings followed by a list of numbered phrases or sentences. For each numbered phrase or sentence, select the one heading that is most closely related to it and fill in the corresponding oval on the answer sheet. Each heading may be used once, more than once, or not at all in each group.

Questions 8–11

(A) Okazaki fragments

(B) Transposons

(C) Lagging strand

(D) Leading strand

(E) hnRNA

8. DNA segments that can move around the genome

9. The strand that is first assembled in discrete nucleotide segments

10. The discontinuous strand during DNA replication

11. Unprocessed RNA molecules that are precursors