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 

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

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

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

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

16. Which of the following hormone secreted from hypothalamus? (A) thyrotropin releasing hormone (B) oxytocin (C) luteinizing hormone (D) glucagon (E) glucocorticoids

17. Which of the following is NOT a factor influencing membrane fluidity? (A) number of double bond in lipids (B) temperature (C) flip-flop move of lipids (D) cholesterol (E) none of the above

18. Which of the following is required for synthesis of prothrombin and blood coagulation factors in hepatocyte? (A) folic acid (B) vitamin K (C) vitamin B12 (D) vitamin A (E) vitamin B1