Question 1

Which of the following characteristics does NOT apply to buffers?

Accepted Answer

A) They have relatively flat titration curves at the pH(s)where they buffer. 
B) They resist changes in their pH as acid or base is added. 
C) They are typically composed of a weak acid and its conjugate base. 
D) They buffer best for polyprotic acids half-way between the 2 pKa values. 
A) They have relatively flat titration curves at the pH(s)where they buffer. 
B) They resist changes in their pH as acid or base is added. 
C) They are typically composed of a weak acid and its conjugate base. 
D) They buffer best for polyprotic acids half-way between the 2 pKa values. D

Question 2

The pKₐs of phosphoric acid are 2.1,7.2,and 12.4.Which of the following values is the correct estimate of the pH of the resulting solution prepared by mixing 1.0 mole of solid disodium phosphate (Na₂HPO₄)and 1.25 moles of hydrochloric acid?

Accepted Answer

A) pH < 2.1 
B) pH = 2.1 
C) 2.1 < pH < 7.2 
D) pH = 7.2 
A) pH < 2.1 
B) pH = 2.1 
C) 2.1 < pH < 7.2 
D) pH = 7.2 C

Question 3

Under which of these conditions does pH = pKₐ?

Accepted Answer

A) log ([A-]/[HA])= 1 
B) [A-] >> [HA] 
C) [A-] = [HA] 
D) log ([HA]/[A-])= 1 
A) log ([A-]/[HA])= 1 
B) [A-] >> [HA] 
C) [A-] = [HA] 
D) log ([HA]/[A-])= 1 B

Question 4

Which of the following is a trait of hydrogen bonds in ice?

Accepted Answer

A) weak 
B) non-directional 
C) straight 
D) responsibility for the higher density of ice over liquid water 
A) weak 
B) non-directional 
C) straight 
D) responsibility for the higher density of ice over liquid water

Question 5

Which of the following will occur if an abundance of an organic acid with a pKa of 3.9 is found in the bloodstream?

Accepted Answer

A) It will be mostly protonated. 
B) It will be mostly deprotonated. 
C) It will form an effective buffer. 
D) It will cause metabolic alkalosis. 
A) It will be mostly protonated. 
B) It will be mostly deprotonated. 
C) It will form an effective buffer. 
D) It will cause metabolic alkalosis.

Question 6

Which of the following acids is NOT a weak electrolyte?

Accepted Answer

A) hydrochloric acid 
B) acetic acid 
C) lactic acid 
D) phosphoric acid 
A) hydrochloric acid 
B) acetic acid 
C) lactic acid 
D) phosphoric acid

Question 7

At what pH are buffer systems most effective?

Accepted Answer

A) within 1 pH unit of the pKa value 
B) within 2 pH units of the pKa value 
C) within 3 pH units of the pKa value 
D) within 4 pH units of the pKa value 
A) within 1 pH unit of the pKa value 
B) within 2 pH units of the pKa value 
C) within 3 pH units of the pKa value 
D) within 4 pH units of the pKa value

Question 8

How many times more H⁺ does grapefruit juice at pH 3.2 contain compared to orange juice at pH 4.3?

Accepted Answer

A) 10-7.5 
B) 10-2 
C) 0.9 
D) 12 
A) 10-7.5 
B) 10-2 
C) 0.9 
D) 12

Question 9

Which of the following is NOT a characteristic of water?

Accepted Answer

A) high surface tension 
B) high dielectric constant 
C) positive volume of melting 
D) high capacity to form hydrogen bonds 
A) high surface tension 
B) high dielectric constant 
C) positive volume of melting 
D) high capacity to form hydrogen bonds

Question 10

Which of the following is the strongest type of bonding that occurs between water and the polar functional groups on non-ionic polar solutes?

Accepted Answer

A) ionic 
B) hydrophobic 
C) electrostatic 
D) hydrogen 
A) ionic 
B) hydrophobic 
C) electrostatic 
D) hydrogen

Question 11

A plasma pH of 6.8 does not seem too far away from a normal pH of 7.4.How many times greater is the H⁺ concentration at pH 6.8 compared to pH 7.4?

Accepted Answer

A) 0.1 
B) 0.6 
C) 4 
D) 10 
A) 0.1 
B) 0.6 
C) 4 
D) 10

Question 12

Which of the following is the purpose of the physiological mechanism of hyperventilation?

Accepted Answer

A) to lower [CO₂ (g)] in the blood and increase blood pH 
B) to raise [CO₂ (g)] in the blood and increase blood pH 
C) to lower [CO₂ (g)] in the blood and decrease blood pH 
D) to raise [CO₂ (g)] in the blood and decrease blood pH 
A) to lower [CO₂ (g)] in the blood and increase blood pH 
B) to raise [CO₂ (g)] in the blood and increase blood pH 
C) to lower [CO₂ (g)] in the blood and decrease blood pH 
D) to raise [CO₂ (g)] in the blood and decrease blood pH

Question 13

Which of the following explains how cells store substances such as amino acids and sugars in order to minimize the osmotic pressure created by the contents of their cytosol?

Accepted Answer

A) in monomeric form 
B) in dimeric form 
C) in trimeric form 
D) in polymeric form 
A) in monomeric form 
B) in dimeric form 
C) in trimeric form 
D) in polymeric form

Question 14

The enzyme fumarase has a pH optimum of about 7.6.Which of the following would be the buffer of choice to study this enzyme?

Accepted Answer

A) tris-hydroxymethyl aminomethane (Ka = 8.32 × 10-9,pKa = 8.07) 
B) lactic acid (Ka = 1.38 × 10-4,pKa = 3.86) 
C) bicarbonate (Ka = 6.3 × 10-11,pKa = 10.24) 
D) acetic acid (Ka = 1.74 × 10-5,pKa = 4.76) 
A) tris-hydroxymethyl aminomethane (Ka = 8.32 × 10-9,pKa = 8.07) 
B) lactic acid (Ka = 1.38 × 10-4,pKa = 3.86) 
C) bicarbonate (Ka = 6.3 × 10-11,pKa = 10.24) 
D) acetic acid (Ka = 1.74 × 10-5,pKa = 4.76)

Question 15

Which of the following specifies the average lifetime of a hydrogen bond connection in water?

Accepted Answer

A) 10 milliseconds 
B) 10 microseconds 
C) 10 nanoseconds 
D) 10 picoseconds 
A) 10 milliseconds 
B) 10 microseconds 
C) 10 nanoseconds 
D) 10 picoseconds

Question 16

Which of the following compounds is included in amphiphilic molecules?

Accepted Answer

A) salts of fatty acids 
B) sugars 
C) acidic amino acids 
D) inorganic salts 
A) salts of fatty acids 
B) sugars 
C) acidic amino acids 
D) inorganic salts

Question 17

Which of the following weak acids would make the best buffer at pH = 5.0?

Accepted Answer

A) acetic acid (Ka = 1.74 × 10-5,pKa = 4.76) 
B) bicarbonate (Ka = 6.3 × 10-11,pKa = 10.24) 
C) tris-hydroxymethyl aminomethane (Ka = 8.32 × 10-9,pKa = 8.07) 
D) lactic acid (Ka = 1.38 × 10-4,pKa = 3.86) 
A) acetic acid (Ka = 1.74 × 10-5,pKa = 4.76) 
B) bicarbonate (Ka = 6.3 × 10-11,pKa = 10.24) 
C) tris-hydroxymethyl aminomethane (Ka = 8.32 × 10-9,pKa = 8.07) 
D) lactic acid (Ka = 1.38 × 10-4,pKa = 3.86)

Question 18

The pKₐs of phosphoric acid are 2.1,7.2,and 12.4.Which of the following values is the resulting pH if equal amounts of Na₂HPO₄ and NaH₂PO₄ are mixed in water?

Accepted Answer

A) 2.1 
B) 4.65 
C) 7.2 
D) 9.8 
A) 2.1 
B) 4.65 
C) 7.2 
D) 9.8

Question 19

Which of the following is NOT a property of water that renders it so suited to its role as a medium of life?

Accepted Answer

A) unrivalled ability to form hydrogen bonds 
B) unusually high dielectric constant,which explains its ability to surround ions and increase the ions' attraction for one another 
C) unparalleled ability to orient around non-polar solutes to promote hydrophobic interactions 
D) a small,but significant,tendency to form H⁺ and OH⁻²⁻ ions 
A) unrivalled ability to form hydrogen bonds 
B) unusually high dielectric constant,which explains its ability to surround ions and increase the ions' attraction for one another 
C) unparalleled ability to orient around non-polar solutes to promote hydrophobic interactions 
D) a small,but significant,tendency to form H⁺ and OH⁻²⁻ ions

Question 20

How many hydrogen bonds can a single liquid water molecule make?

Accepted Answer

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

Exam 2: Water: the Medium of Life

Which of the following characteristics does NOT apply to buffers?

The pKₐs of phosphoric acid are 2.1,7.2,and 12.4.Which of the following values is the correct estimate of the pH of the resulting solution prepared by mixing 1.0 mole of solid disodium phosphate (Na₂HPO₄)and 1.25 moles of hydrochloric acid?

Under which of these conditions does pH = pKₐ?

Which of the following is a trait of hydrogen bonds in ice?

Which of the following will occur if an abundance of an organic acid with a pKa of 3.9 is found in the bloodstream?

Which of the following acids is NOT a weak electrolyte?

At what pH are buffer systems most effective?

How many times more H⁺ does grapefruit juice at pH 3.2 contain compared to orange juice at pH 4.3?

Which of the following is NOT a characteristic of water?

Which of the following is the strongest type of bonding that occurs between water and the polar functional groups on non-ionic polar solutes?

A plasma pH of 6.8 does not seem too far away from a normal pH of 7.4.How many times greater is the H⁺ concentration at pH 6.8 compared to pH 7.4?

Which of the following is the purpose of the physiological mechanism of hyperventilation?

Which of the following explains how cells store substances such as amino acids and sugars in order to minimize the osmotic pressure created by the contents of their cytosol?

The enzyme fumarase has a pH optimum of about 7.6.Which of the following would be the buffer of choice to study this enzyme?

Which of the following specifies the average lifetime of a hydrogen bond connection in water?

Which of the following compounds is included in amphiphilic molecules?

Which of the following weak acids would make the best buffer at pH = 5.0?

The pKₐs of phosphoric acid are 2.1,7.2,and 12.4.Which of the following values is the resulting pH if equal amounts of Na₂HPO₄ and NaH₂PO₄ are mixed in water?

Which of the following is NOT a property of water that renders it so suited to its role as a medium of life?

How many hydrogen bonds can a single liquid water molecule make?

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Thermodynamics of Biological Systems

Amino Acids

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Lipid Biosynthesis

Membranes and Membrane Transport

The Reception and Transmission of Extracellular Information

Enzymes Kinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Nutrition and the Organization of Metabolism

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Nitrogen Acquisition and Amino Acid Metabolism

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Synthesis and Degradation of Nucleotides

Recombinant Dna: Cloning and Creation of Chimeric Genes

DNA Metabolism: Replication, recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Post-Transcriptional Regulation of Gene Expression

Completing the Protein Life Cycle: Folding, processing, and Degradation

Metabolic Integration and Organ Specialization

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