CH 222 Test Bank Biochemistry Test 1 - Centennial College
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CH 222
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CH 222
The dipole moment in a water molecule Which statement about hydrogen bonds is NOT
true?
A) Hydrogen bonds account for the anomalously high boiling point of water.
B) In liquid water, the average water molecule forms hydrogen bonds with three to
four other water molecules.
C) Individual hydroge...
1. The dipole moment in a water molecule Which statement about hydrogen bonds is NOT
true?
A) Hydrogen bonds account for the anomalously high boiling point of water.
B) In liquid water, the average water molecule forms hydrogen bonds with three to
four other water molecules.
C) Individual hydrogen bonds are much weaker than covalent bonds.
D) Individual hydrogen bonds in liquid water exist for many seconds and sometimes
for minutes.
E) The strength of a hydrogen bond depends on the linearity of the three atoms
involved in the bond.
2. A TRUE statement about hydrophobic interactions is that they:
A) are the driving force in the formation of micelles of amphipathic compounds in
water.
B) do not contribute to the structure of water-soluble proteins.
C) have bonding energies of approximately 20–40 Kjoule per mole.
D) involve the ability of water to denature proteins.
E) primarily involve the effect of polar solutes on the entropy of aqueous systems.
3. Hydrophobic interactions make important energetic contributions to:
A) binding of a hormone to its receptor protein.
B) enzyme-substrate interactions.
C) membrane structure.
D) three-dimensional folding of a polypeptide chain.
E) All of the answers are correct.
4. Dissolved solutes alter some physical (colligative) properties of the solvent water
because they change the:
A) concentration of the water.
B) hydrogen bonding of the water.
C) ionic bonding of the water.
D) pH of the water.
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, E) temperature of the water.
5. Osmosis is movement of a:
A) charged solute molecule (ion) across a membrane.
B) gas molecule across a membrane.
C) nonpolar solute molecule across a membrane.
D) polar solute molecule across a membrane.
E) water molecule across a membrane.
6. A hydronium ion:
A) has the structure H3O+.
B) is a hydrated hydrogen ion.
C) is a hydrated proton.
D) is the usual form of one of the dissociation products of water in solution.
E) All of the answers are correct.
7. The pH of a solution of 1 M HCl is:
A) 0.
B) 0.1.
C) 1.
D) 10.
E) –1.
8. The pH of a solution of 0.1 M NaOH is:
A) 0.1.
B) 1.0.
C) 12.8.
D) 13.
E) 14.
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, 9. Which statement is TRUE about the properties of aqueous solutions?
A) A pH change from 5.0 to 6.0 reflects an increase in the hydroxide ion concentration
([OH–]) of 20%.
B) A pH change from 8.0 to 6.0 reflects a decrease in the proton concentration ([H+])
by a factor of 100.
C) Charged molecules are generally insoluble in water.
D) Hydrogen bonds form readily in aqueous solutions.
E) The pH can be calculated by adding 7 to the value of the pOH.
10. The pH of a sample of blood is 7.4, while gastric juice is pH 1.4. The blood sample has:
A) 0.189 times the [H+] as the gastric juice.
B) 5.29 times lower [H+] than the gastric juice.
C) 6 times lower [H+] than the gastric juice.
D) 6000 times lower [H+] than the gastric juice.
E) one million times lower [H+] than the gastric juice.
11. The aqueous solution with the LOWEST pH is:
A) 0.01 M HCl.
B) 0.1 M acetic acid (pKa = 4.86).
C) 0.1 M formic acid (pKa = 3.75).
D) 0.1 M HCl.
E) 10–12 M NaOH.
12. The aqueous solution with the HIGHEST pH is:
A) 1 M HCl.
B) 1 M NH3 (pKa = 9.25).
C) 0.5 M NaHCO3 (pKa = 3.77).
D) 0.1 M NaOH.
E) 0.001 M NaOH.
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, 13. Phosphoric acid is tribasic, with pKa's of 2.14, 6.86, and 12.4. The ionic form that
predominates at pH 3.2 is:
A) H3PO4.
B) H2PO4–.
C) HPO42–.
D) PO43–.
E) None of the answers is correct.
14. Which statement about buffers is TRUE?
A) A buffer composed of a weak acid of pKa = 5 is stronger at pH 4 than at pH 6.
B) At pH values lower than the pKa, the salt concentration is higher than that of the
acid.
C) The pH of a buffered solution remains constant no matter how much acid or base is
added to the solution.
D) The strongest buffers are those composed of strong acids and strong bases.
E) When pH = pKa, the weak acid and salt concentrations in a buffer are equal.
15. A compound has a pKa of 7.4. To 100 mL of a 1.0 M solution of this compound at pH
8.0 is added 30 mL of 1.0 M hydrochloric acid. The resulting solution is pH:
A) 6.5.
B) 6.8.
C) 7.2.
D) 7.4.
E) 7.5.
16. The Henderson-Hasselbalch equation:
A) allows the graphic determination of the molecular weight of a weak acid from its
pH alone.
B) does not explain the behavior of di- or tri-basic weak acids.
C) employs the same value for pKa for all weak acids.
D) is equally useful with solutions of acetic acid and of hydrochloric acid.
E) relates the pH of a solution to the pKa and the concentrations of acid and conjugate
base.
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