9. Which of the following ion channel causes the reflectory period when neuron cannot response to another stimulus shortly after an action potential?
(A) sodium ion channel
(B) potassium ion channel
(C) proton channel
(D) chloride channel
(E) calcium ion channel

5. What will be the amino acid carried by a tRNA whose anticodon sequence is 5’-CAU-3’ ? (AUG: Met; CAU: His; UAC: Tyr; GUA: Val; CGU: Arg) (A) Met (B) His (C) Tyr (D) Val (E) Arg

6. Which of the following statement is NOT correct about immunoglobulin producing B cells? (A) B cell does not express its immunoglobulin gene unless primed by antigen. (B) B cells rearrange their immunoglobulin gene during their development. (C) The VDJ rearrangement creates the diversity of immunoglobulin produced by B cells. (D) Somatic mutation of immunoglobulin gene is one way to produce high affinity antibody. (E) B cell anergy is one way to induce tolerance.

7. Huntington disease (HD) is inherited dominantly. If homozygote patient of HD is about 4% in a population, what will be the percentage of normal individuals in this population? (A) 96% (B) 81% (C) 64% (D) 49% (E) 20%

8. In plant leave, products of photosynthesis is collected in which of the following leave cells? (A) collecting cell (B) transfer cell (C) tracheid (D) boundle sheath cell (E) endodermal cell

10. Glucose in human hepatocyte can be synthesized from which combination of the following non-sugar sources? ①  adenine ②  alanine ③ lactate  ④  palmitate⑤glycerol (A) ① ② ③ (B)①④ (C) ② ③ ④ ⑤ (D) ④ ⑤(E) ② ③⑤

11. Acne is caused by infection of the sebaceous glands by Propionibacterium acne, which is Gram-positive bacterium whose cell wall composed of which of the following? (A) thick lipopolysaccharide layer (B) thick peptidoglycan layer (C) thin lipopolysaccharide layer over a thick peptidoglycan layer (D) thick lipopolysaccharide layer over a thin peptidoglycan layer (E) thick lipopolysaccharide layer over a thick peptidoglycan layer

12. Which of the following is the least possible growth limitation factor for a plant community? (A) nitrogen source (B) carbon source (C) phosphorus source (D) potassium source (E) water source 

13. According to their pigmentation, which algal group would be most likely to perform photosynthesis in the deepest sea? (A) red algae (B) green algae (C) brown algae (D) golden algae (E) blue-green algae

14. An action potential of neuron is characterized by the following, except_____  . (A) it is initiated by opening of voltage-gated potassium channels (B) it is regarded as a regenerative response (C) it is regarded as a all-or-none response (D) it does not degrade in magnitute with space or time (E) it is transmembrane potential changes that occur in most axons

15. What is hormone most active in a person who is subjective to short-term starvation? (A) insulin (B) glucagon (C) epinephrine (D) oxytocin (E) glucocorticoids