25. Which chromatography method would best separate proteins based on their isoelectric points (pI)?
(A) Ion exchange chromatography
(B) Gel filtration chromatography
(C) Reverse-phase chromatography
(D) Affinity chromatography
(E) IMAC (Immobilized metal affinity chromatography)

21. Vesicular transport describes the budding and fusion behavior of vesicles. Which of the following statement(s) is   correct   regarding vesicular transport? (1) The vesicular transport process is ATP-dependent, as ATP is required for both the budding and fusion of vesicles. (2) COPI-coated vesicles are primarily involved in anterograde transport from the endoplasmic reticulum (ER) to the Golgi apparatus. (3) Dynamin is a GTPase that is responsible for the vesicle budding from the donor membrane during clathrin-mediated endocytosis. (A) 3 only (B) 1 and 3 (C) 2 and 3 (D) 1 and 2 (E) All of above are correct.

22. Membrane transport describes different ways for molecules to across the cell membrane. Which of the following statements is   correct   regarding membrane transport? (1) In facilitated diffusion, molecules move across the membrane through a protein channel or carrier down their concentration gradient. (2) The presence of aquaporins in the cell membrane facilitates the active transport of water molecules into and out of the cell. (3) Secondary active transport does not directly utilize ATP but relies on the electrochemical gradient created by primary active transport. (A) 3 only (B) 1 and 2 (C) 1 and 3 (D) 2 and 3 (E) All of above are correct.

23. Which of the following statement(s) is   correct   regarding ER-Golgi transport pathway? (1) The process of cisternal maturation suggests Golgi cisternae is used to replenish its resident enzymes without forming the vesicles. (2) The Rab GTPase proteins play a role in vesicular transport and in regulating the maturation of Golgi cisternae, coordinating their movement and fusion. (3) Signal sequence is responsible for targeting a protein to the ER membrane during translation. (A) 3 only (B) 1 and 2 (C) 1 and 3 (D) 2 and 3 (E) All of above are correct.

24. Which of the following statements about translesion DNA synthesis (TLS) is true? (A) It uses conventional DNA polymerase δ to replicate across lesions. (B) It is a repair mechanism for DNA breaks. (C) It prevents replication collapse by allowing specialized polymerases to bypass lesions. (D) It occurs only in prokaryotes, not in eukaryotes. (E) It strictly follows base-pairing rules without introducing mutations.

26. To repair the insertion/deletion created by the Crispr/Cas9 editing mainly needs: (A) Base excision repair (B) Nuclear excision repair (C) Mismatch repair (D) Homologous recombination (E) Non-homologous end-joining

27. Antibody-dependent cytotoxicity will evoke: (A) cell proliferation (B) auto-immune response. (C) Epidermal-mesenchymal transition (D) apoptosis of cancer cells (E) activation of PI3K/Akt signaling

28. The molecular mechanism of the gene expression revealed the role of specific transcription factors, promoters, enhancers, and cofactors involved. Which experiment is incorrect? (A) The transcription factor-binding sequences can be determined with chromatin-immunoprecipitation (IP) followed by DNA sequencing. (B) The promoter and enhancer were cloned from the cDNA library for the reporter assay. (C) The transcription factor was knocked down by siRNA for the loss-of-function analysis. (D) The transcription factor was overexpressed with a viral vector for the gain-of-function analysis. (E) The transcription factor-associated cofactors were identified by the IP-Mass Spectrometry (MS) analysis.

29. Long noncoding RNAs (lncRNAs) are described as long transcripts more than 200 nucleotides, lacking protein-coding potential. LncRNAs participate in regulation of gene expression at multiple levels via interacting with DNA, RNA and proteins. (A) LncRNAs are transcribed by RNA pol II but no intron, no cap and no poly（Ａ） tail. (B) LncRNAs have high expression levels. (C) LncRNAs are more enriched in the cytoplasm. (D) LncRNAs recruit PRC2 complex and lead to H3K27 methylation for gene inhibition. (E) All are correct.

30. The 2024 Nobel Prize in Physiology or Medicine was awarded to Victor Ambros and Gary Ruvkun for discovering microRNA and its role in post-transcriptional gene regulation. Which statement is incorrect? (A) Lin-4 was the first microRNA to be discovered by Victor Ambros's team. (B) Victor Ambros's team found that lin-4 negatively regulates LIN-14 protein expression. (C) Gary Ruvkun's team found the 5'UTR of lin-14 mRNA is required for lin-4 inhibition. (D) In C . elegans, the microRNA lin-4 critically regulates developmental timing (E) Most microRNAs are conserved across species.

31. There is no codon for the amino acid hydroxyproline, but this amino acid is a prominent feature of collagen structure. Which of the following is a likely explanation? (A) Hydroxyproline is substituted for proline after translation by a cut and patch mechanism. (B) Proline is covalently modified to give hydroxyproline after translation. (C) There is an alternative mechanism for synthesis of proteins that contain hydroxyproline. (D) All of above are likely explanations. (E) It is not possible to form a hypothesis from the information given.