9. The human genome project shows about 20,000 human protein-coding genes. However, the total expressed proteins are more than 20,000. What mechanism can one gene express more than one protein?
(A) Alternative splicing
(B) Alternative promoter
(C) Alternative poly（Ａ） signal.
(D) Alternative translation initiation site
(E) All mechanisms are involved.

5. CRISPR-Cas9 is commonly used for genome editing. The "Cas9" portion of the system is: (A) A reverse transcriptase enzyme (B) An RNA-guided exonuclease (C) An RNA-guided endonuclease (D) A RNA helicase (E) An DNA-guided endonuclease

6. Which one is required for the progression of G1 to S phase? (A) Phosphorylated p53 (B) Unphosphorylated p53 (C) Unphosphorylated Rb (D) Hypophosphorylated Rb (E) Hyperphosphorylated Rb

7. Which one is the driving force to M phase? (A) Cdk1-cyclin B (B) Cdk2-cyclin B (C) Cdk4-cyclin A (D) Cdk4-cyclin B (E) Cdk6-cyclin A

8. Which one is often used in flow cytometry to detect DNA synthesis? (A) BrdU (B) Insulin (C) Hydroxyurea (D) Nocodazole (E) DideoxyNTP

10. In 1970, David Baltimore discovered reverse transcriptase (RT), which could flow information from RNA to DNA. Which statement is incorrect? (A) Telomerase is one kind of RT. (B) RT is found in retrovirus. (C) RT needs a primer and template. (D) RT synthesizes DNA from 3' to 5'. (E) The RT-qPCR is a method for RNA level determination.

11. All are true for translation in eukaryotic cells except: (A) transcription and translation are spatially separated. (B) mRNAs are monocistronic. (C) transcription occurs in the nucleus. (D) primary transcripts undergo processing to mature mRNAs. (E) All are true.

12. Mitochondrial and chloroplastic ribosomes resemble _____ ribosomes. (A) prokaryotic (B) lower eukaryotic (C) higher eukaryotic (D) no other (E) None are true.

13. Forensic uses of DNA to identify victims or criminals exploit the following trait in DNA: (A) Footprinting. (B) DNA with proteins bound moves slower in gel electrophoresis. (C) Site directed mutations. (D) Differences in sizes of DNA fragments (RFLPs). (E) None of the above.

14. Which of the following is normally found in a eukaryotic membrane? (1) Octylglucoside (2) Cholesterol (3) Sphingomyelin (4) Ganglioside GMI (5) Phosphatidylinositol (A) (1), (2), and (5) (B) (1), (2), (3), and (5) (C) (2), (3), (4), and (5) (D) (2), (3), and (5) (E) All of the above

15. Why do cells not have membrane transport proteins for O2? (A) Because oxygen can dissolve in the lipid bilayer and diffuse in and out rapidly without the need for a transporter. (B) Because oxygen can dissolve in water and leak in via water channels. (C) Because they need to keep the oxygen concentration low inside the reducing environment of the cell. (D) Because oxygen transport across a membrane is energetically unfavorable. (E) Because oxygen is transported in and out of the cell in special oxygen-carrying proteins such as hemoglobin.