31. Which one CANNOT be used as a molecular "brake" for the immune system?
(A) PD1
(B) PD-L1
(C) EGFR
(D) NKG2A
(E) CTLA4

27. Which of the following statements regarding immune response is correct? (1) In cellular immunity, T lymphocytes, including cytotoxic T lymphocytes and killer T cells are responsible for the recognition and killing of foreign invaders.  (2) Killer T lymphocytes have an especially low count in a patient with advanced AIDS. (3) Histamine is produced by host cells infected by viruses.  (4) Immunological memory is due to long lived B cells that secrete a specific antibody. (A) (1) and (2) are correct (B) (1) and (3) are correct (C) (1) and (4) are correct (D) (1), (2) and (4) are correct (E) (1), (3) and (4) are correct

28. The order for the construction of a cDNA fragment from mRNA is to: (A) treat with reverse transcriptase, digest with RNase, add G residues to the 3' end, bind oligo-dC, treat with DNA polymerase and bind oligo-dT. (B) digest with RNase, add G residues to the 3' end, treat with reverse transcriptase, add G residues to the 3' end and treat with DNA polymerase. (C) bind oligo-dT, treat with reverse transcriptase, digest with RNase, add G residues to the 3' end, bind oligo-dC, treat with DNA polymerase. (D) bind oligo-dC, treat with reverse transcriptase, digest with RNase, add G residues to the 3' end, bind oligo-dT and treat with DNA polymerase. (E) None of above is correct

29. Which one is NOT involved in COPII vesicle formation? (A) GTPase Sar1 (GTP-bound state) (B) guanine nucleotide exchange factor (GEF) Sec12 (C) Coat Sec23/Sec24 heterodimer. (D) Outer coat Sec13/Sec31 heterotetramer (E) From Golgi to lysosome

30. Which molecule is degraded by ubiquitination during sister chromatid separation? (A) Cohesin (B) Securin (C) Cyclin A (D) Cdk2 (E) Cdk1

32. Which one is NOT correlated with longevity? (A) high levels of plasma sphingomyelin (B) low levels of PUFA-containing triacylglycerols (C) high level of plasma cholesterol (D) tryptophan (E) high energy expenditure

33. Which one has asymmetric cell division? (A) Hepatocyte (B) Splenocyte (C) Intestinal epidermal cell (D) Stem cell (E) Skin cell

34. Which molecule does NOT participate in autophagy? (A) ULK1 (B) Beclin1 (C) LC3 (D) ATG7 (E) Caspase

35. The results of human genome project show that more than 98% of the human genomes are composed of non-coding DNA (ncDNA) which are never represented within the amino acid sequence of expressed proteins. Which description is incorrect? (A) About 20,000 human proteins have been annotated in databases, which is significantly larger than that of the fruit fly. (B) The extensive use of alternative pre-mRNA splicing in humans provides the ability to build a very large number of modular proteins. (C) Some ncDNAs contain genes for RNA molecules with important biological functions. (D) Transposable elements belong to ncDNAs, which account for at least 50% of the human genome. (E) Some ncDNAs contain intron, 5' UTR and 3'UTR.

36. A microRNA (miRNA) is a small non-coding RNA, which can down-regulate mRNA expression levels. Please choose the correct statement about animal miRNA. (A) It is transcribed by RNA polymerase I. (B) It is 10-20 nucleotides in length single-stranded RNA. (C) It is perfectly complementary to its mRNA targets. (D) It is a ribonuclease. (E) It forms a RISC complex to destabilize its mRNA targets.

37. Post-translational modifications modulate a protein activity. To study the functional effect of a protein phosphoprylated at Ser/Thr, we generate a non-phosphorylatable mutant by changing to AlA What amino acids are used for creating a phosphomimetic mutant? (A) Asp and Glu (B) Lys and Arg (C) Leu and Ile (D) Gln and Arg (E) Tyr and Phe