24. In the complex ion , the oxidation number of Co is
(A) +1
(B) +2
(C)+3
(D) -2
(E) -1

20. You have 500.0 mL of a buffer solution containing 0.20 M acetic acid (CH3COOH) and 0.30 M sodium acetate (CH3COONa). What will the pH of this solution be after the addition of 20.0 mL of 1.00 M NaOH solution?(A) 4.41 (B) 4.74 (C)4.56 (D) 4.92 (E) 5.07

21. Which one of the following reactions would you expect to have the lowest △S°? (A)(B) (C) (D) (E) All the above reactions have the same △S°

22. The formula “” should be a. Alkanes； b. Alkenes； c. Alkynes； d. Cycloalkane (A) a or b (B) b or c (C)c or d (D) a or d (E) b or d

23. Which of the following is most soluble in water (A) (B) (C) (D) (E)

25. Which complex has the less unpaired electrons (A) (B) (C)Na3[CoCl6] ； (D) [Cr(NH3)3(H2O)Cl2]Cl (E)

1. Aquaporins (A) allow water to cross the plasma membrane via facilitated diffusion. (B) allow water to cross the plasma membrane against its concentration gradient. (C) allow for the active transport of water. (D) are found in all cells. (E) all are correct.

2. The nitrogen-fixing activity of cyanobacteria takes place in (A) thylakoid (B) heterocyte (C) chloroplast (D) plasmid (E) endospore

複選題3. Which substance could be an enzyme cofactor? (A) protein (B) polypeptide (C) zinc atom (D) ribosome (E) vitamin

4. How does inhibition of an enzyme-catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor? (A) Competitive inhibitors interfere with the enzyme； noncompetitive inhibitors interfere with the reactants. (B) Competitive inhibitors bind to the enzyme reversibly； noncompetitive inhibitors bind to it irreversibly. (C) Competitive inhibitors change the enzyme's tertiary structure； noncompetitive inhibitors cause polypeptide subunits to dissociate. (D) Competitive inhibitors bind to the active site of the enzyme； noncompetitive inhibitors bind to a different site. (E) Noncompetitive inhibitors bind to the active site of the enzyme； competitive inhibitors bind to a different site.

5. Which statement regarding the function of mitosis is false? (A) Mitosis allows organisms to grow. (B) Mitosis promotes genetic diversity. (C) Mitosis is necessary for asexual reproduction in eukaryotes. (D) Mitosis promotes repair tissues. (E) All are incorrect.