Question 1

Which of the following atoms could interact through a hydrogen bond?

Accepted Answer

A) the oxygen of a ketone and the hydrogen of an aldehyde 
B) the oxygen of methanol and a hydrogen on the methyl carbon of methanol 
C) the hydrogen of an amine and the oxygen of an alcohol 
D) the hydrogen on an aromatic ring and the oxygen of carbon dioxide 
E) none of the above 
A) the oxygen of a ketone and the hydrogen of an aldehyde 
B) the oxygen of methanol and a hydrogen on the methyl carbon of methanol 
C) the hydrogen of an amine and the oxygen of an alcohol 
D) the hydrogen on an aromatic ring and the oxygen of carbon dioxide 
E) none of the above C

Question 2

What happens to DNA when placed into an aqueous solution at physiological pH?

Accepted Answer

A) individual DNA molecules attract each other due to presence of positive and negative charges 
B) individual DNA molecules repel each other due to presence of negative charges 
C) individual DNA molecules repel each other due to presence of positive charges 
D) DNA molecules bind to negatively charged proteins 
E) none of the above 
A) individual DNA molecules attract each other due to presence of positive and negative charges 
B) individual DNA molecules repel each other due to presence of negative charges 
C) individual DNA molecules repel each other due to presence of positive charges 
D) DNA molecules bind to negatively charged proteins 
E) none of the above B

Question 3

Given the structure of a glucose molecule,which of the following explains the hydrogen bonding between glucose and water?

Accepted Answer

A) H-bonds will form with glucose always being the H-bond donor 
B) H-bonds will form with water always being the H-bond donor 
C) each glucose molecule could H-bond with as many as 17 water molecules 
D) due to the cyclic structure of glucose,H-bonding with water does not occur 
E) none of the above 
A) H-bonds will form with glucose always being the H-bond donor 
B) H-bonds will form with water always being the H-bond donor 
C) each glucose molecule could H-bond with as many as 17 water molecules 
D) due to the cyclic structure of glucose,H-bonding with water does not occur 
E) none of the above C

Question 4

Use the equilibrium equation of the blood buffer to predict what would happen to blood pH if respiration were to slow significantly.

Accepted Answer

@#IMG-DLM& 
Slowing of respiration would

Question 5

Citric acid is a triprotic acid with three carboxylic acid groups having pKa values of 3.1,4.8,and 6.4.If a solution of citric acid has a pH of 5.5,what can be said about the predominant protonation state of the citric acid?

Accepted Answer

A) 1 carboxylic acid group is deprotonated,2 are protonated 
B) 2 carboxylic acid groups are deprotonated,1 is protonated 
C) all 3 carboxylic acid groups are deprotonated 
D) all 3 carboxylic acid groups are protonated 
E) the protonation state cannot be determined 
A) 1 carboxylic acid group is deprotonated,2 are protonated 
B) 2 carboxylic acid groups are deprotonated,1 is protonated 
C) all 3 carboxylic acid groups are deprotonated 
D) all 3 carboxylic acid groups are protonated 
E) the protonation state cannot be determined

Question 6

What pH range is generally considered to be the physiological pH range?

Accepted Answer

A) 1.5-3.0 
B) 4.5-7.0 
C) 5.5-9.0 
D) 6.5-8.0 
E) 7.5-10.0 
A) 1.5-3.0 
B) 4.5-7.0 
C) 5.5-9.0 
D) 6.5-8.0 
E) 7.5-10.0

Question 7

Lactic acid is a common product of actively working muscle.It is transported via the bloodstream to the liver.What percent of lactic acid is ionized in the bloodstream if the pH is 7.40 and the pKa is 3.86?

Accepted Answer

99.97% (10

Question 8

You have been asked to determine the pKa of an unknown acid.In a solution at pH 7.0,you find that 24% of the acid is in its deprotonated form.What is the pKa of the acid?

Accepted Answer

A) 7.9 
B) 7.5 
C) 6.5 
D) 5.6 
E) none of the above 
A) 7.9 
B) 7.5 
C) 6.5 
D) 5.6 
E) none of the above

Question 9

A typical amino acid has a carboxylic acid and an amine with pKa values of 2.3 and 9.6,respectively.In a solution of pH 4.5,which of the following best describes the protonation and charge state of the amino acid?

Accepted Answer

A) carboxylic acid: protonated and neutral;amine: deprotonated and negative 
B) carboxylic acid: protonated and neutral;amine: protonated and neutral 
C) carboxylic acid: deprotonated and negative;amine: protonated and neutral 
D) carboxylic acid: deprotonated and negative;amine: protonated and positive 
E) carboxylic acid: deprotonated and negative;amine: deprotonated and neutral 
A) carboxylic acid: protonated and neutral;amine: deprotonated and negative 
B) carboxylic acid: protonated and neutral;amine: protonated and neutral 
C) carboxylic acid: deprotonated and negative;amine: protonated and neutral 
D) carboxylic acid: deprotonated and negative;amine: protonated and positive 
E) carboxylic acid: deprotonated and negative;amine: deprotonated and neutral

Question 10

Since pKa = -log Ka,which of the following is a correct statement?

Accepted Answer

A) acetic acid (pKa = 4.7)is stronger than lactic acid, (pKa = 3.9) 
B) lactic acid, (pKa = 3.9)is weaker than all forms of phosphoric acid, (pKa = 2.1,6.9 and 12.4) 
C) since the pKa for conversion of the ammonium ion to ammonia is 9.25,ammonia is a weaker base then the acetate ion 
D) for carbonic acid with pKa values of 6.3 and 10.3,the bicarbonate ion is a stronger base than the carbonate ion 
E) none of the above 
A) acetic acid (pKa = 4.7)is stronger than lactic acid, (pKa = 3.9) 
B) lactic acid, (pKa = 3.9)is weaker than all forms of phosphoric acid, (pKa = 2.1,6.9 and 12.4) 
C) since the pKa for conversion of the ammonium ion to ammonia is 9.25,ammonia is a weaker base then the acetate ion 
D) for carbonic acid with pKa values of 6.3 and 10.3,the bicarbonate ion is a stronger base than the carbonate ion 
E) none of the above

Question 11

Which of the following acids or bases is least likely to be encountered in a biochemical setting?

Accepted Answer

A) nitric acid 
B) acetic acid 
C) ammonia 
D) citric acid 
E) phosphoric acid 
A) nitric acid 
B) acetic acid 
C) ammonia 
D) citric acid 
E) phosphoric acid

Question 12

Which of the following best explains the hydrogen bonding that occurs in water?

Accepted Answer

A) the average number of H-bonds formed by one water molecule is the same in liquid and solid water,the only difference is the duration of the H-bond 
B) the number of H-bonds formed by one water molecule is greater in liquid water than in solid water 
C) the structure of liquid water is best described as flickering clusters of H-bonds due to the relative short duration of individual H-bonds 
D) each water molecule is capable of forming 8 H-bonds: 2 from each lone pair of electrons and 2 from each hydrogen 
E) none of the above 
A) the average number of H-bonds formed by one water molecule is the same in liquid and solid water,the only difference is the duration of the H-bond 
B) the number of H-bonds formed by one water molecule is greater in liquid water than in solid water 
C) the structure of liquid water is best described as flickering clusters of H-bonds due to the relative short duration of individual H-bonds 
D) each water molecule is capable of forming 8 H-bonds: 2 from each lone pair of electrons and 2 from each hydrogen 
E) none of the above

Question 13

Given the pKa values for phosphoric acid of 2.14,6.86 and 12.4,what is the ratio of HPO42-/H2PO4- in a typical muscle cell where the pH is 7.2?

Accepted Answer

A) 0.46 
B) 2.2 
C) 6.3 $\times$ 10-6 
D) 1.1 $\times$ 105 
E) none of the above 
A) 0.46 
B) 2.2 
C) 6.3 $\times$ 10-6 
D) 1.1 $\times$ 105 
E) none of the above

Question 14

Which of the following is the conjugate acid of hydrogen phosphate,HPO42-?

Accepted Answer

A) H2PO3- 
B) H2PO4- 
C) H3PO4 
D) H2PO42- 
E) none of the above 
A) H2PO3- 
B) H2PO4- 
C) H3PO4 
D) H2PO42- 
E) none of the above

Question 15

Glutamic acid contains two carboxylic acid groups (pKa values of 2.2 and 4.2)and an amine group (pKa 9.7).What is the pI for glutamic acid?

Accepted Answer

A) 3.2 
B) 6.0 
C) 6.5 
D) 7.0 
E) none of the above 
A) 3.2 
B) 6.0 
C) 6.5 
D) 7.0 
E) none of the above

Question 16

If gastric juice has a pH of about 1.5,which of the following would be predominantly deprotonated in the stomach?

Accepted Answer

A) phenol (pKa = 9.9) 
B) acetic acid (pKa = 4.7) 
C) lactic acid, (pKa = 3.9) 
D) phosphoric acid (pKa = 2.1) 
E) hydrochloric acid (pKa = -6) 
A) phenol (pKa = 9.9) 
B) acetic acid (pKa = 4.7) 
C) lactic acid, (pKa = 3.9) 
D) phosphoric acid (pKa = 2.1) 
E) hydrochloric acid (pKa = -6)

Question 17

Imidazole is a commonly used buffer in biochemistry labs.With a pKa of 7.0,what would be the ratio of base to acid at pH 7.4?

Accepted Answer

Question 18

In the following titration curve,what does the inflection point represent?

Accepted Answer

A) pH of solution equals pKa of weak acid 
B) concentration of weak acid and conjugate base are equal 
C) the pH where the solution would function most effectively as a buffer 
D) the weak acid is 50% protonated,50% deprotonated 
E) all of the above 
A) pH of solution equals pKa of weak acid 
B) concentration of weak acid and conjugate base are equal 
C) the pH where the solution would function most effectively as a buffer 
D) the weak acid is 50% protonated,50% deprotonated 
E) all of the above

Question 19

Which of the following is the most likely noncovalent interaction observed between a carboxylic acid and an alcohol?

Accepted Answer

A) charge-charge interaction 
B) charge-dipole interaction 
C) dipole-dipole interaction 
D) dipole-induced dipole interaction 
E) formation of an ester bond 
A) charge-charge interaction 
B) charge-dipole interaction 
C) dipole-dipole interaction 
D) dipole-induced dipole interaction 
E) formation of an ester bond

Question 20

If a buffer is made with the pH below the pKa of the weak acid,the ratio of [base]/[acid] will be:

Accepted Answer

A) less than 1 
B) greater than 1 
C) equal to 1 
D) equal to 0 
E) cannot be determined 
A) less than 1 
B) greater than 1 
C) equal to 1 
D) equal to 0 
E) cannot be determined

Exam 2: The Matrix of Life: Weak Interactions in an Aqueous Environment

Which of the following atoms could interact through a hydrogen bond?

What happens to DNA when placed into an aqueous solution at physiological pH?

Given the structure of a glucose molecule,which of the following explains the hydrogen bonding between glucose and water?

Use the equilibrium equation of the blood buffer to predict what would happen to blood pH if respiration were to slow significantly.

Citric acid is a triprotic acid with three carboxylic acid groups having pKa values of 3.1,4.8,and 6.4.If a solution of citric acid has a pH of 5.5,what can be said about the predominant protonation state of the citric acid?

What pH range is generally considered to be the physiological pH range?

Lactic acid is a common product of actively working muscle.It is transported via the bloodstream to the liver.What percent of lactic acid is ionized in the bloodstream if the pH is 7.40 and the pKa is 3.86?

You have been asked to determine the pKa of an unknown acid.In a solution at pH 7.0,you find that 24% of the acid is in its deprotonated form.What is the pKa of the acid?

A typical amino acid has a carboxylic acid and an amine with pKa values of 2.3 and 9.6,respectively.In a solution of pH 4.5,which of the following best describes the protonation and charge state of the amino acid?

Since pKa = -log Ka,which of the following is a correct statement?

Which of the following acids or bases is least likely to be encountered in a biochemical setting?

Which of the following best explains the hydrogen bonding that occurs in water?

Given the pKa values for phosphoric acid of 2.14,6.86 and 12.4,what is the ratio of HPO42-/H2PO4- in a typical muscle cell where the pH is 7.2?

Which of the following is the conjugate acid of hydrogen phosphate,HPO42-?

Glutamic acid contains two carboxylic acid groups (pKa values of 2.2 and 4.2)and an amine group (pKa 9.7).What is the pI for glutamic acid?

If gastric juice has a pH of about 1.5,which of the following would be predominantly deprotonated in the stomach?

Imidazole is a commonly used buffer in biochemistry labs.With a pKa of 7.0,what would be the ratio of base to acid at pH 7.4?

In the following titration curve,what does the inflection point represent?

Which of the following is the most likely noncovalent interaction observed between a carboxylic acid and an alcohol?

If a buffer is made with the pH below the pKa of the weak acid,the ratio of [base]/[acid] will be:

The Scope of Biochemistry

The Energetics of Life

Nucleic Acids

Introduction to Proteins: the Primary Level of Protein Structure

The Three-Dimensional Structure of Proteins

Protein Function and Evolution

Contractile Proteins and Molecular Motors

Carbohydrates: Sugars,saccharides,glycans

Lipids,membranes and Cellular Transport

Enzymes: Biological Catalysts

Chemical Logic of Metabolism

Carbohydrate Metabolism: Glycolysis, gluconeogenesis, glycogen Metabolism, and the Pentose Phosphate Pathway

Citric Acid Cycle and Glyoxylate Cycle

Electron Transport, oxidative Phosphorylation, and Oxygen Metabolism

Photosynthesis

Lipid Metabolism I: Fatty Acids,triacylglycerols,and Lipoproteins

Interorgan and Intracellular Coordination of Energy Metabolism in Vertebrates

Lipid Metabolism Ii: Membrane Lipids, steroids, isoprenoids, and Eicosanoids

Metabolism of Nitrogenous Compounds I: Principles of Biosynthesis, utilization, and Turnover

Metabolism of Nitogenous Compounds Ii: Amino Acids, porphyrins, and Neurotransmitters

Nucleotide Metabolism

Mechanisms of Signal Transduction

Genes,genomes and Chromosomes

Dna Replication

Dna Restructuring: Repair,recombination,rearrangement,amplification

Information Readout: Transcription and Post-Transcriptional Processing

Information Decoding: Translation and Post-Translational Protein Processing

Regulation of Gene Expression

Filters

Citric acid is a triprotic acid with three carboxylic acid groups having pK_a values of 3.1,4.8,and 6.4.If a solution of citric acid has a pH of 5.5,what can be said about the predominant protonation state of the citric acid?

Lactic acid is a common product of actively working muscle.It is transported via the bloodstream to the liver.What percent of lactic acid is ionized in the bloodstream if the pH is 7.40 and the pK_a is 3.86?

You have been asked to determine the pK_a of an unknown acid.In a solution at pH 7.0,you find that 24% of the acid is in its deprotonated form.What is the pK_a of the acid?

A typical amino acid has a carboxylic acid and an amine with pK_a values of 2.3 and 9.6,respectively.In a solution of pH 4.5,which of the following best describes the protonation and charge state of the amino acid?

Since pK_a = -log K_a,which of the following is a correct statement?

Given the pK_a values for phosphoric acid of 2.14,6.86 and 12.4,what is the ratio of HPO₄^2-/H₂PO₄^- in a typical muscle cell where the pH is 7.2?

Which of the following is the conjugate acid of hydrogen phosphate,HPO₄²^-?

Glutamic acid contains two carboxylic acid groups (pK_a values of 2.2 and 4.2)and an amine group (pK_a 9.7).What is the pI for glutamic acid?

Imidazole is a commonly used buffer in biochemistry labs.With a pK_a of 7.0,what would be the ratio of base to acid at pH 7.4?

If a buffer is made with the pH below the pK_a of the weak acid,the ratio of [base]/[acid] will be: