Question 1

Which of the following molecules will not form hydrogen bonds?

Accepted Answer

A)  CH4 
B)  NH3 
C)  H2O 
D)  HF 
A)  CH4 
B)  NH3 
C)  H2O 
D)  HF

Question 2

Exhibit 2A The structure of ATP with various groups labeled.Group III is the entire phosphate group.
  
-Refer to Exhibit 2A. Which of the functional groups is the most electrophilic?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  The answer cannot be determined without further information. 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  The answer cannot be determined without further information.

Question 3

Which will dissociate most in water, a weak acid or a strong acid?

Accepted Answer

A)  A weak acid. 
B)  A strong acid 
C)  They should dissociate about the same. 
D)  It's impossible to predict. 
A)  A weak acid. 
B)  A strong acid 
C)  They should dissociate about the same. 
D)  It's impossible to predict.

Question 4

Which of the following is not considered a van der Waal's force?

Accepted Answer

A)  dipole - dipole bond 
B)  dipole - induced dipole bond 
C)  induced dipole - induced dipole bond 
D)  ion - dipole bond 
A)  dipole - dipole bond 
B)  dipole - induced dipole bond 
C)  induced dipole - induced dipole bond 
D)  ion - dipole bond

Question 5

Hydrogen bonds explain which of the following properties of water?

Accepted Answer

A)  Water is a great solvent for all ionic and polar molecules. 
B)  Water has high melting and boiling points for its small size. 
C)  Ice expands when frozen. 
D)  Both the abnormal melting and freezing points and that ice expands when frozen. 
E)  Hydrogen bonds explain all of these properties. 
A)  Water is a great solvent for all ionic and polar molecules. 
B)  Water has high melting and boiling points for its small size. 
C)  Ice expands when frozen. 
D)  Both the abnormal melting and freezing points and that ice expands when frozen. 
E)  Hydrogen bonds explain all of these properties.

Question 6

Using the Henderson-Hasselbalch equation, calculate the pH of an ammonia buffer when the NH3:NH4+ ratio is 0.4 moles:0.6 moles. (pK = 9.75)

Accepted Answer

A)  7.40 
B)  9.07 
C)  9.25 
D)  9.43 
E)  11.05 
A)  7.40 
B)  9.07 
C)  9.25 
D)  9.43 
E)  11.05

Question 7

Calculate the final pH of a solution made by the addition of 10 mL of a 0.5 M NaOH solution to 500 mL of a 0.4 M HA originally at pH = 5.0 (pKa = 5.0) Neglect the volume change.

Accepted Answer

A)  6.10 
B)  5.09 
C)  7.00 
D)  5.55 
A)  6.10 
B)  5.09 
C)  7.00 
D)  5.55

Question 8

If the pH of 1 liter of a 1.0 M carbonate buffer is 7.0, what is actual number of moles of H2CO3 and HCO3?? (pK = 6.37) $$\begin{array} { l l l } 
& \text { moles of } \mathbf { H } _ { 2 } \mathbf { C O } _ { 3 } & \text { moles of } \mathrm { HCO } _ { 3 } \
 \text { I. } & 0.86 & 0.14 \
\text { II. } & 0.81 & 0.19 \
\text { III. } & 0.76 & 0.24 \
\text { IV. } & 0.19 & 0.81 \
\text { V. } & 0.14 & 0.86
\end{array}$$

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  V 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  V

Question 9

An ammonia buffer contains NH3:NH4+ in a ratio of 0.4 moles:0.6 moles (pK = 9.75). What will be the pH if you add 0.01 moles of HCl to this buffer?

Accepted Answer

A)  8.98 
B)  9.04 
C)  9.25 
D)  9.46 
E)  9.52 
A)  8.98 
B)  9.04 
C)  9.25 
D)  9.46 
E)  9.52

Question 10

If atoms with greatly differing electronegativities form a bond, that bond will be

Accepted Answer

A)  polar. 
B)  nonpolar. 
C)  amphipathic. 
D)  acidic. 
A)  polar. 
B)  nonpolar. 
C)  amphipathic. 
D)  acidic.

Question 11

Buffers which lack biological activity and are unlikely to interfere with any biochemical reactions include:

Accepted Answer

A)  Tris. 
B)  Hepes. 
C)  Phosphate. 
D)  Both Tris and HEPES. 
E)  All of these. 
A)  Tris. 
B)  Hepes. 
C)  Phosphate. 
D)  Both Tris and HEPES. 
E)  All of these.

Question 12

If a solution has a pH = 6, the [H+] is

Accepted Answer

A)  6 M 
B)  106 M 
C)  10−6 M 
D)  0.6 M 
A)  6 M 
B)  106 M 
C)  10−6 M 
D)  0.6 M

Question 13

Which of the following properties of water are related to its ability to form hydrogen bonds?

Accepted Answer

A)  boiling point 
B)  melting point 
C)  density 
D)  solvent potency 
E)  all of the choices 
A)  boiling point 
B)  melting point 
C)  density 
D)  solvent potency 
E)  all of the choices

Question 14

Exhibit 2B
Contains information on the pK's of some common buffers.
$\begin{array}{llrc}
\text { Buffer } & \mathbf{p K} 1 & \mathbf{p K 2} & \mathbf{p K} 3 \
\hline \text { Acetate } & 4.75 & & \
\text { Ammonia } & 9.25 & & \
\text { Carbonic acid } & 6.37 & 10.20 & \
\text { Citric acid } & 3.09 & 4.75 & 5.41 \
\text { Formic Acid } & 3.75 & & \
\text { Phosphoric acid } & 2.14 & 7.20 & 12.4 \
\text { Pyruvic acid } & 2.50 & & \
\text { Tris } & 8.3 & &
\end{array}$

-Refer to Exhibit 2B. The enzyme lysozyme has an optimum pH close to 5. A suitable buffer would be:

Accepted Answer

A)  Acetate 
B)  Carbonate 
C)  Phosphate 
D)  Pyruvate 
E)  None of these is a suitable buffer for this reaction. 
A)  Acetate 
B)  Carbonate 
C)  Phosphate 
D)  Pyruvate 
E)  None of these is a suitable buffer for this reaction.

Question 15

Which has the greater pKa, a weak acid or a strong acid?

Accepted Answer

A)  A weak acid. 
B)  A strong acid 
C)  They should dissociate about the same. 
D)  It's impossible to predict. 
A)  A weak acid. 
B)  A strong acid 
C)  They should dissociate about the same. 
D)  It's impossible to predict.

Question 16

Many of the properties of water can be accounted for by the fact that

Accepted Answer

A)  it is polar 
B)  it forms hydrogen bonds 
C)  it is a bent molecule 
D)  all of these are true 
A)  it is polar 
B)  it forms hydrogen bonds 
C)  it is a bent molecule 
D)  all of these are true

Question 17

Consider a reaction that produces a significant amount of hydrogen ion and is to be carried out a pH 7. Only two acids are available for making the buffer solution. The pKa values for acids A and B are 6.3 and 7.3, respectively. Which acid would serve as the optimum buffer for this reaction? Or would carrying out the reaction in water simply serve as well?

Accepted Answer

A)  acid A 
B)  acid B 
C)  water 
D)  both acids would be equally effective 
A)  acid A 
B)  acid B 
C)  water 
D)  both acids would be equally effective

Question 18

True hydrogen bonds can NOT form between hydrogen and this element:

Accepted Answer

A)  N 
B)  F 
C)  C 
D)  O 
E)  All of these elements can form hydrogen bonds. 
A)  N 
B)  F 
C)  C 
D)  O 
E)  All of these elements can form hydrogen bonds.

Question 19

The non-covalent interaction below associated with the strongest force in aqueous solution is

Accepted Answer

A)  dipole-induced dipole 
B)  hydrophobic interactions 
C)  hydrogen bonding 
D)  van der Waals forces 
A)  dipole-induced dipole 
B)  hydrophobic interactions 
C)  hydrogen bonding 
D)  van der Waals forces

Question 20

A buffer solution at pH 10 has a ratio of [HA]/[A−] of 10. What is the pKa of the acid?

Accepted Answer

A)  8 
B)  9 
C)  10 
D)  11 
E)  12 
A)  8 
B)  9 
C)  10 
D)  11 
E)  12

Exam 2: Water: the Solvent for Biochemical Reactions

Which of the following molecules will not form hydrogen bonds?

Exhibit 2A The structure of ATP with various groups labeled.Group III is the entire phosphate group. -Refer to Exhibit 2A. Which of the functional groups is the most electrophilic?

Which will dissociate most in water, a weak acid or a strong acid?

Which of the following is not considered a van der Waal's force?

Hydrogen bonds explain which of the following properties of water?

Using the Henderson-Hasselbalch equation, calculate the pH of an ammonia buffer when the NH3:NH4+ ratio is 0.4 moles:0.6 moles. (pK = 9.75)

Calculate the final pH of a solution made by the addition of 10 mL of a 0.5 M NaOH solution to 500 mL of a 0.4 M HA originally at pH = 5.0 (pKa = 5.0) Neglect the volume change.

If the pH of 1 liter of a 1.0 M carbonate buffer is 7.0, what is actual number of moles of H2CO3 and HCO3?? (pK = 6.37) moles of moles of I. 0.86 0.14 II. 0.81 0.19 III. 0.76 0.24 IV. 0.19 0.81 V. 0.14 0.86

An ammonia buffer contains NH3:NH4+ in a ratio of 0.4 moles:0.6 moles (pK = 9.75). What will be the pH if you add 0.01 moles of HCl to this buffer?

If atoms with greatly differing electronegativities form a bond, that bond will be

Buffers which lack biological activity and are unlikely to interfere with any biochemical reactions include:

If a solution has a pH = 6, the [H+] is

Which of the following properties of water are related to its ability to form hydrogen bonds?

Which has the greater pKa, a weak acid or a strong acid?

Many of the properties of water can be accounted for by the fact that

True hydrogen bonds can NOT form between hydrogen and this element:

The non-covalent interaction below associated with the strongest force in aqueous solution is

A buffer solution at pH 10 has a ratio of [HA]/[A−] of 10. What is the pKa of the acid?

Biochemistry and the Organization of Cells

Amino Acids and Peptides

The Three-Dimensional Structure of Proteins

Protein Purification and Characterization Techniques

The Behavior of Proteins: Enzymes

The Behavior of Proteins: Enzymes, Mechanisms, and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids: How Structure Conveys Information

Biosynthesis of Nucleic Acids: Replication

Transcription of the Genetic Code: Biosynthesis of RNA

Protein Synthesis: Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses, Cancer, and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism: Cellular Signaling

Filters

Using the Henderson-Hasselbalch equation, calculate the pH of an ammonia buffer when the NH₃:NH₄⁺ ratio is 0.4 moles:0.6 moles. (pK = 9.75)

If the pH of 1 liter of a 1.0 M carbonate buffer is 7.0, what is actual number of moles of H₂CO₃ and HCO₃?? (pK = 6.37) moles of moles of I. 0.86 0.14 II. 0.81 0.19 III. 0.76 0.24 IV. 0.19 0.81 V. 0.14 0.86

An ammonia buffer contains NH₃:NH₄⁺ in a ratio of 0.4 moles:0.6 moles (pK = 9.75). What will be the pH if you add 0.01 moles of HCl to this buffer?

If a solution has a pH = 6, the [H⁺] is

Which has the greater pK_a, a weak acid or a strong acid?

A buffer solution at pH 10 has a ratio of [HA]/[A−] of 10. What is the pK_a of the acid?