5. Eukaryotes solve the problem of replicating the ends of their linear chromosomes by:
(A) terminal redundancy whereby each end of the chromosome is duplicated allowing recombination.
(B) enzyme activity that uses an RNA template and reverse transcription in a series of repeat cycles.
(C) by covalently linking the two strands at each end of the linear chromosome to form a circle.
(D) using a protein as a primer.
(E) all of the above.

1. Which of the following statements about regulation of the lac operon is true? (A) Glucose in the growth medium does not affect the inducibility by lactose. (B) Glucose in the growth medium decreases the inducibility by lactose. (C) Glucose in the growth medium increases the inducibility by lactose. (D) Its expression is regulated mainly at the level of translation. (E) The lac operon is fully induced whenever lactose is present.

2. Which one of the following is not involved in steroid hormone action? (A) Transcription activation and repression (B) Hormone-receptor complexes (C) Specific DNA sequences (D) Cell surface receptors (E) Zinc fingers

3. The PCR reaction mixture does not include: (A) DNA containing the sequence to be amplified. (B) all four deoxynucleoside triphosphates. (C) heat-stable DNA polymerase. (D) oligonucleotide primer(s). (E) DNA ligase.

4. When bacterial DNA replication introduces a mismatch in a double-stranded DNA, the methyl-directed repair system: (A) cannot distinguish the template strand from the newly replicated strand. (B) changes both the template strand and the newly replicated strand. (C) corrects the mismatch by changing the newly replicated strand. (D) corrects the mismatch by changing the template strand. (E) corrects the DNA strand that is methylated.

6. What chemical force does atomic force microscopy operate upon? (A) Hydrogen bond (B) Ionic force (C) Covalent bond (D) van der Waals (E) magnetic force

7. GPI stands for glycosylphosphatidylinositol that anchors a protein to a membrane. Which of the following is correct? (A) A GPI anchor is added when a protein is in the cytoplasm. (B) A GPI anchor is added when a protein is in the ER. (C) A GPI anchor is added when a protein is in the endosome. (D) A GPI anchor is added when a protein is in the Golgi apparatus. (E) A GPI anchor is added when a protein is in the plasma membrane.

8. What is the oxidation status of the carbon in methane? (A) -5 (B) -4 (C) -3 (D) -2 (E) -1

複選題9. Which of the following reaction is it that is mediated by pyridoxal phosphate (Vitamin B6)? (A) Phosphorylation (B) Isomerization (C) Racemization (D) Glycosylation (E) Lipidation

10. Which of the following membrane lipid is it that serves as a eat-me signal in an apoptotic cell? (A) Phosphatidylinositol (B) Phosphatidylethanolamine (C) Phosphatidylserine (D) Phosphatidylcholine (E) Sphingosine-1-phosphate

11. Which of the following statements is correct regarding the biosynthesis of purine nucleotides? (A) Glycine, aspartate, and glutamine serve as nitrogen sources for the purine ring. (B) The concentration of 5-phosphoribosyl 1-pyrophosphate is the major factor regulating the rate of de novo purine nucleotide biosynthesis. (C) Lesch-Nyhan syndrome is caused by a defect in hypoxanthine-guanine phosphoribosyl transferase, an enzyme involved in purine salvage. (D) AMP and GMP inhibit hypoxanthine-guanine phosphoribosyl transferase, which converts hypoxanthine and guanine into IMP and GMP. (E) All of the above are correct.