Question 1

Which of the following is not true?

Accepted Answer

A)  A buffer is a solution which maintains a solution at a neutral pH 
B)  Buffer solutions are made to resist change in pH 
C)  Zwitterion buffers are less likely to interfere with biological reactions than non-zwitterions 
D)  HEPES is a zwitterion buffer 
A)  A buffer is a solution which maintains a solution at a neutral pH 
B)  Buffer solutions are made to resist change in pH 
C)  Zwitterion buffers are less likely to interfere with biological reactions than non-zwitterions 
D)  HEPES is a zwitterion buffer A

Question 2

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 C

Question 3

Which of the following is true regarding hydrogen bonds.

Accepted Answer

A)  They can only form between two different molecules 
B)  They are important in protein folding but not DNA structure 
C)  They are important in DNA structure but not protein folding 
D)  They can be found within a single molecule 
A)  They can only form between two different molecules 
B)  They are important in protein folding but not DNA structure 
C)  They are important in DNA structure but not protein folding 
D)  They can be found within a single molecule D

Question 4

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 5

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 6

Which of the following acids would serve as a good buffer for a reaction at pH = 8.0? $$\begin{array} { l l l } 
& \mathbf { K } _ { \mathbf { a } } \
\text { I. } & \text { acetic acid } & 1.76 \times 10 - ^ { 5 } \
\text { II. } & \mathrm { H } _ { 2 } \mathrm { PO } _ { 4 } - & 6.31 \times 10 ^ { - 8} \
\text { III. } & \text { bicarbonate } & 5.6 \times 10 ^{- 11 }\
\text { IV. } & \text { TRIS } & 5.01 \times 10 ^ { -  9}
\end{array}$$

Accepted Answer

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

Question 7

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 8

Which of the following is true?

Accepted Answer

A)  The pH of a solution where the A− to HA ratio is 1 has a pH = pKa. 
B)  If the pH does not equal the pKa, the solution is not a buffer. 
C)  The best buffer for any experiment will always have a pH equal to the pKa. 
D)  If a buffer has more weak acid than conjugate base, the pH will be higher than the pKa. 
A)  The pH of a solution where the A− to HA ratio is 1 has a pH = pKa. 
B)  If the pH does not equal the pKa, the solution is not a buffer. 
C)  The best buffer for any experiment will always have a pH equal to the pKa. 
D)  If a buffer has more weak acid than conjugate base, the pH will be higher than the pKa.

Question 9

Bases are

Accepted Answer

A)  proton donors. 
B)  proton acceptors. 
C)  hydrogen bond donors. 
D)  hydrogen bond acceptors. 
A)  proton donors. 
B)  proton acceptors. 
C)  hydrogen bond donors. 
D)  hydrogen bond acceptors.

Question 10

Which of the following molecules is amphipathic?

Accepted Answer

A)  sodium chloride 
B)  acetic acid 
C)  benzene 
D)  palmitic acid 
A)  sodium chloride 
B)  acetic acid 
C)  benzene 
D)  palmitic acid

Question 11

A buffer solution

Accepted Answer

A)  is used to control the pH of a solution 
B)  contains at least 100 times more of a weak acid than its conjugate base 
C)  contains at least 100 times less of a weak acid than its conjugate base 
D)  always has a pH of 7 
A)  is used to control the pH of a solution 
B)  contains at least 100 times more of a weak acid than its conjugate base 
C)  contains at least 100 times less of a weak acid than its conjugate base 
D)  always has a pH of 7

Question 12

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 13

How do hydrogen bonds tend to affect the melting and boiling points of substances?

Accepted Answer

A)  They tend to increase both melting and boiling points. 
B)  They tend to decrease both melting and boiling points. 
C)  They tend to increase melting points and decrease boiling points. 
D)  They tend to decrease melting points and increase boiling points. 
E)  They do not have any affect on either melting or boiling points. 
A)  They tend to increase both melting and boiling points. 
B)  They tend to decrease both melting and boiling points. 
C)  They tend to increase melting points and decrease boiling points. 
D)  They tend to decrease melting points and increase boiling points. 
E)  They do not have any affect on either melting or boiling points.

Question 14

What is the maximum number of hydrogen bonds a single water molecule can form?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5 
A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 15

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 16

Which of the following is true about ionic compounds?

Accepted Answer

A)  They are more likely to dissolve in non-polar solvents than covalent compounds. 
B)  They always dissolve completely in water. 
C)  They never dissolve in polar solvents. 
D)  Some of them dissolve completely in water or other polar solvents, while others do not. 
A)  They are more likely to dissolve in non-polar solvents than covalent compounds. 
B)  They always dissolve completely in water. 
C)  They never dissolve in polar solvents. 
D)  Some of them dissolve completely in water or other polar solvents, while others do not.

Question 17

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 18

Is water an acid or a base?

Accepted Answer

A)  Water is an acid. 
B)  Water is a base. 
C)  Water is both an acid and a base. 
D)  Water is neither an acid nor a base. 
A)  Water is an acid. 
B)  Water is a base. 
C)  Water is both an acid and a base. 
D)  Water is neither an acid nor a base.

Question 19

A hydrogen bond is a special type of

Accepted Answer

A)  dioole - dipole bond 
B)  induced dipole - induced dipole bond 
C)  covalent bond 
D)  ionic bond 
A)  dioole - dipole bond 
B)  induced dipole - induced dipole bond 
C)  covalent bond 
D)  ionic bond

Question 20

Which substance would be the best buffer at pH 8 if it had to be able to buffer against either acid or base?

Accepted Answer

A)  one with a pKa of 7 
B)  one with a pKa of 8 
C)  one with a pKa of 9 
D)  The pKa of a substance doesn't tell you whether it would be a good buffer at this pH. 
A)  one with a pKa of 7 
B)  one with a pKa of 8 
C)  one with a pKa of 9 
D)  The pKa of a substance doesn't tell you whether it would be a good buffer at this pH.

Exam 2: Water: the Solvent for Biochemical Reactions

Which of the following is not true?

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

Which of the following is true regarding hydrogen bonds.

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

A micelle is a structure which

Which of the following acids would serve as a good buffer for a reaction at pH = 8.0? I. acetic acid 1.76\times10 II. - 6.31\times1 III. bicarbonate 5.6\times1 IV. TRIS 5.01\times1

For an acid that undergoes this reaction: HA ↔ H+ + A− Ka =

Which of the following is true?

Bases are

Which of the following molecules is amphipathic?

A buffer solution

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

How do hydrogen bonds tend to affect the melting and boiling points of substances?

What is the maximum number of hydrogen bonds a single water molecule can form?

Which of the following statements about hydrogen bonds is false?

Which of the following is true about ionic compounds?

Hydrogen bonds

Is water an acid or a base?

A hydrogen bond is a special type of

Which substance would be the best buffer at pH 8 if it had to be able to buffer against either acid or base?

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

For an acid that undergoes this reaction: HA ↔ H⁺ + A− K_a =

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