34. Which one is correct for the description of transposons?
(A) It occurs only in bacteria.
(B) Some transposons do jump from one genome location to another, in what is called replicative transposition.
(C) It plays little or no role in evolution.
(D) Few can move to many alternative locations in the DNA.
(E) None of the above.

30. Ribosomes attached to rough ER are the site for synthesis of many types of secretary proteins. Which of the following mechanism is typically used for nascent protein insertion into the mammalian ER membrane? (A) Pretranslational. (B) Cotranslational. (C) Post-translational. (D) Cotranscriptional. (E) All of the above.

31. MPF is a cyclin-Cdk complex that was discovered first in Xenopus egg. Its activity fluctuates during cell cycle. Which of the following is NOT its characteristic? (A) Fluctuation of the cyclin concentration is the same as MPF activity. (B) The peak of the MPF activity is G2 phase. (C) The peak of the MPF activity is M phase. (D) The breakdown of the MPF occurs abruptly during M phase. (E) The activity of the MPF promotes mitosis by phosphorylating various proteins. .

32. Which of the following human DNA polymerases is responsible for replicating the mitochondrial DNA? (A) Alpha. (B) Beta. (C) Gamma. (D) Delta. (E) Theta.

33. Which one is the correct sequence of protein synthesis? 1. An aminoacyl-tRNA binds to the A site 2. A peptide bond forms between the new amino acid and a polypeptide chain 3. tRNA leves the P site, and the P site remains vacant 4. A small ribosomal subunit binds with Mrna 5. tRNA translocates to the P site(A) 5,4,3,2,1 (B) 2,4,5,1,3 (C) 4,1,2,5,3 (D) 4,1,3,2,5 (E) 1,3,2,4,5

35. Proto-oncogenes can change into oncogenes that cause cancer, which one can best explain the characteristic of proto-oncogenes? (A) p53 gene and ras gene belong to one of proto-oncogenes. (B) Pro-oncogenes are the normal cellular genes. (C) Cells produce proto-oncogenes as they age. (D) All of the above. (E) None of the above.

36. Which one of modifications is likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis? (A) Altering the charges of the DNA fragment. (B) Increasing or decreasing the length of the DNA fragment. (C) Increasing the concentration of a gel. (D) Methylating the cytosine base within the DNA fragment. (E) All of the above.

37. Proteomics is a new kind of challenge because (A) the number of proteins in humans probably far exceeds the number of genes. (B) a cell’s proteins differ with cell type. (C) proteins are extremely varied in structure and chemical properties. (D) some proteins can not be easily analyzed due to their amounts or solubility. (E) All of the above.

38. Which of the following is considered an intrinsic isolating mechanism? (A) Gametic incompatibility. (B) Sterile offspring. (C) Ecological isolation. (D) Timing of courtship display. (E) All of the above.

39. If organisms A, B, C belong to the same phylum, but to different classes and if organism D, E, and F belong to the same class but to different orders, which one of pairs of organisms would be expected to show the least degree of structural homology? (A) A and B (B) C and F (C) A and F (D) B and D (E) D and F

40. Which one of the statements in the fact that some fungi are NOT beneficial to agriculture? (A) They recycle nutrients that are linked to dead organic matter. (B) They form mycoses on plants. (C) They contribute to the initial stages of soil formation from rock. (D) They may harbor photosynthetic partners that add nitrogenous compounds to the soils. (E) None of the above.