Question 1

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 2

Which of the following molecules has polar bonds but is itself not polar?

Accepted Answer

A)  NH3 
B)  CO2 
C)  CH4 
D)  H2O 
A)  NH3 
B)  CO2 
C)  CH4 
D)  H2O

Question 3

Which of the following statements about hydrogen bonds is false?

Accepted Answer

A)  The donor is a hydrogen atom bonded to a less electronegative atom then hydrogen. 
B)  The more linear the bond, the stronger the attraction. 
C)  The acceptor must contain a non-bonded pair of electrons. 
D)  It is a type of non-covalent bond. 
A)  The donor is a hydrogen atom bonded to a less electronegative atom then hydrogen. 
B)  The more linear the bond, the stronger the attraction. 
C)  The acceptor must contain a non-bonded pair of electrons. 
D)  It is a type of non-covalent bond.

Question 4

The pH of a solution of 0.04 M HCl is:

Accepted Answer

A)  4 
B)  1.4 
C)  0.4 
D)  0.04 
E)  The pH cannot be determined 
A)  4 
B)  1.4 
C)  0.4 
D)  0.04 
E)  The pH cannot be determined

Question 5

Exhibit 2B Contains information on the pK's of some common buffers.
  Which of the following is important to know when deciding if a given buffer will be effective for an experiment?

Accepted Answer

A)  the pKa of the buffer compound 
B)  the buffer capacity 
C)  the concentration of the buffer 
D)  whether the experiment is likely to generate hydrogen ions or hydroxide ions 
E)  all of these are important considerations 
A)  the pKa of the buffer compound 
B)  the buffer capacity 
C)  the concentration of the buffer 
D)  whether the experiment is likely to generate hydrogen ions or hydroxide ions 
E)  all of these are important considerations

Question 6

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 7

A micelle is a structure which

Accepted Answer

A)  aggregates with other micelles in water. 
B)  has its polar groups on the outside and non-polar groups on the inside when in water. 
C)  explains how soaps and detergents work. 
D)  has its polar groups on the outside and non-polar groups on the inside when in water and explains how soaps and detergents work. 
E)  All of these are true. 
A)  aggregates with other micelles in water. 
B)  has its polar groups on the outside and non-polar groups on the inside when in water. 
C)  explains how soaps and detergents work. 
D)  has its polar groups on the outside and non-polar groups on the inside when in water and explains how soaps and detergents work. 
E)  All of these are true.

Question 8

The dissociation constant for an acid with a pKa value of 6.0 is

Accepted Answer

A)  1 × 10-6 
B)  -1 × 106 
C)  1 × 106 
D)  -1 × 10-6 
A)  1 × 10-6 
B)  -1 × 106 
C)  1 × 106 
D)  -1 × 10-6

Question 9

Hydrogen bonds

Accepted Answer

A)  play an important role in the solvent properties of water 
B)  are not involved in protein structure 
C)  play a role in the properties of DNA, but not of RNA 
D)  give water a lower boiling point than expected 
A)  play an important role in the solvent properties of water 
B)  are not involved in protein structure 
C)  play a role in the properties of DNA, but not of RNA 
D)  give water a lower boiling point than expected

Question 10

Exhibit 2B Contains information on the pK's of some common buffers.
  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 11

The ratio of a weak acid and its conjugate base at the point of maximum buffering capacity is

Accepted Answer

A)  1/1 
B)  1/10 
C)  10/1 
D)  no definite ratio is needed 
A)  1/1 
B)  1/10 
C)  10/1 
D)  no definite ratio is needed

Question 12

Nonphysiological buffers such as HEPES and PIPES have come into common use because

Accepted Answer

A)  they are inexpensive 
B)  they can be prepared much more easily than other buffers 
C)  they have less tendency to interfere with reactions 
D)  they contain nitrogen 
A)  they are inexpensive 
B)  they can be prepared much more easily than other buffers 
C)  they have less tendency to interfere with reactions 
D)  they contain nitrogen

Question 13

Which of the following classes of compounds is hydrophilic?

Accepted Answer

A)  Sugars 
B)  Fatty acids 
C)  Amino acids 
D)  Sugars and amino acids. 
E)  All of these 
A)  Sugars 
B)  Fatty acids 
C)  Amino acids 
D)  Sugars and amino acids. 
E)  All of these

Question 14

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 15

An HCl solution has a pH = 3.If you dilute 10 mL of the solution to 1000mL,the final pH will be:

Accepted Answer

A)  1.0 
B)  2.0 
C)  The pH does not change. 
D)  4.0 
E)  5.0 
A)  1.0 
B)  2.0 
C)  The pH does not change. 
D)  4.0 
E)  5.0

Question 16

For an acid that undergoes this reaction: HA « H+ + A-
Ka =

Accepted Answer

A)  [H+][A-]/[HA] 
B)  [H+][HA]/[A-] 
C)  [HA][A-]/[H+] 
D)  [A-]/[HA][H+] 
E)  [H+]/[HA][A-] 
A)  [H+][A-]/[HA] 
B)  [H+][HA]/[A-] 
C)  [HA][A-]/[H+] 
D)  [A-]/[HA][H+] 
E)  [H+]/[HA][A-]

Question 17

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 18

Exhibit 2B Contains information on the pK's of some common buffers.
  Refer to Exhibit 2B.A carbonate buffer would work well at this pH:

Accepted Answer

A)  4.0 
B)  6.0 
C)  8.0 
D)  10.0 
E)  6.0 and 10.0 
A)  4.0 
B)  6.0 
C)  8.0 
D)  10.0 
E)  6.0 and 10.0

Question 19

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 20

Exhibit 2A   The structure of ATP with various groups labeled.
Group III is the entire phosphate group.
Refer to Exhibit 2A.Which of the groups could not act as a proton acceptor in a hydrogen bond?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  All can accept a hydrogen in a hydrogen bond. 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  All can accept a hydrogen in a hydrogen bond.

Exam 2: Water: The Solvent for Biochemical Reactions

Hydrogen bonds explain which of the following properties of water?

Which of the following molecules has polar bonds but is itself not polar?

Which of the following statements about hydrogen bonds is false?

The pH of a solution of 0.04 M HCl is:

Exhibit 2B Contains information on the pK's of some common buffers. Which of the following is important to know when deciding if a given buffer will be effective for an experiment?

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

A micelle is a structure which

The dissociation constant for an acid with a pKa value of 6.0 is

Hydrogen bonds

Exhibit 2B Contains information on the pK's of some common buffers. Refer to Exhibit 2B.The enzyme lysozyme has an optimum pH close to 5.A suitable buffer would be:

The ratio of a weak acid and its conjugate base at the point of maximum buffering capacity is

Nonphysiological buffers such as HEPES and PIPES have come into common use because

Which of the following classes of compounds is hydrophilic?

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.

An HCl solution has a pH = 3.If you dilute 10 mL of the solution to 1000mL,the final pH will be:

For an acid that undergoes this reaction: HA « H+ + A- Ka =

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?

Exhibit 2B Contains information on the pK's of some common buffers. Refer to Exhibit 2B.A carbonate buffer would work well at this pH:

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

Exhibit 2A The structure of ATP with various groups labeled. Group III is the entire phosphate group. Refer to Exhibit 2A.Which of the groups could not act as a proton acceptor in a hydrogen bond?

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

The dissociation constant for an acid with a pK_a value of 6.0 is

For an acid that undergoes this reaction: HA « H⁺ + A^- K_a =

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?

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