Question 1

Blood pH is primarily regulated by

Accepted Answer

A)  a protein buffer system. 
B)  the carbon dioxide - carbonic acid - bicarbonate buffer system. 
C)  the phosphate buffering system. 
D)  carbonic acid (H2CO3). 
E)  B and C 
A)  a protein buffer system. 
B)  the carbon dioxide - carbonic acid - bicarbonate buffer system. 
C)  the phosphate buffering system. 
D)  carbonic acid (H2CO3). 
E)  B and C

Question 2

Oil and water do not form a solution due to .

Accepted Answer

A)  the hydrophobic effect 
B)  the inability of oil to hydrogen bond with water 
C)  the nonpolarity of oil 
D)  All of the above (A-
C)  
E)  A and C only 
A)  the hydrophobic effect 
B)  the inability of oil to hydrogen bond with water 
C)  the nonpolarity of oil 
D)  All of the above (A-
C)  
E)  A and C only

Question 3

The buffering capacity of a weak acid and its conjugate base is strongest when the pH = pKa.

Accepted Answer

A) True 
 B)False

Question 4

A molecule or ion is said to be hydrated when it .

Accepted Answer

A)  is neutralized by water 
B)  is surrounded by water molecules 
C)  reacts and forms a covalent bond to water 
D)  aggregates with other molecules or ions to form a micelle in water 
A)  is neutralized by water 
B)  is surrounded by water molecules 
C)  reacts and forms a covalent bond to water 
D)  aggregates with other molecules or ions to form a micelle in water

Question 5

At the midpoint of a titration curve

Accepted Answer

A)  the concentration of a conjugate base is equal to the concentration of a conjugate acid 
B)  the pH equals the pKa 
C)  the ability of the solution to buffer is best 
D)  All of the above 
E)  A and B only 
A)  the concentration of a conjugate base is equal to the concentration of a conjugate acid 
B)  the pH equals the pKa 
C)  the ability of the solution to buffer is best 
D)  All of the above 
E)  A and B only

Question 6

Some ions such as thiocyanate that are poorly solvated in water and can enhance the solubility of nonpolar compounds in water by disordering the water molecules are called .

Accepted Answer

A)  azeotropes 
B)  hydrophobic ions 
C)  zeolytes 
D)  chaotropes 
A)  azeotropes 
B)  hydrophobic ions 
C)  zeolytes 
D)  chaotropes

Question 7

Water molecules that surround a less polar molecule in solution are immobile and ordered.

Accepted Answer

A) True 
 B)False

Question 8

The H+ or H3O+ in cells is the same concentration as that of undissociated water.

Accepted Answer

A) True 
 B)False

Question 9

The aggregation of nonpolar molecules or groups in water is thermodynamically due to the

Accepted Answer

A)  increased entropy of the nonpolar molecules when they associate. 
B)  decreased enthalpy of the system. 
C)  increased entropy of the water molecules. 
D)  very strong van der Waals forces among the nonpolar molecules or groups. 
A)  increased entropy of the nonpolar molecules when they associate. 
B)  decreased enthalpy of the system. 
C)  increased entropy of the water molecules. 
D)  very strong van der Waals forces among the nonpolar molecules or groups.

Question 10

Compounds that ionize when dissolved in water are called .

Accepted Answer

A)  electrolytes 
B)  polar compounds 
C)  hydrophobic compounds 
D)  amphipathic compounds 
A)  electrolytes 
B)  polar compounds 
C)  hydrophobic compounds 
D)  amphipathic compounds

Question 11

The ratio of the concentration of a over describes the proportions of forms of a weak acid necessary to satisfy the Henderson-Hasselbalch equation.

Accepted Answer

A)  conjugate acid; conjugate base 
B)  conjugate base; conjugate acid 
C)  proton donor; proton acceptor 
D)  proton acceptor; proton donor 
E)  B and D 
A)  conjugate acid; conjugate base 
B)  conjugate base; conjugate acid 
C)  proton donor; proton acceptor 
D)  proton acceptor; proton donor 
E)  B and D

Question 12

The water solubility of alcohols with a single hydroxyl group increases as a function of molecular weight.

Accepted Answer

A) True 
 B)False

Question 13

Water is a nucleophile, yet it does not usually hydrolyze macromolecules in cells because

Accepted Answer

A)  covalent bonds linking macromolecule subunits are stable at cell pH. 
B)  covalent bonds linking macromolecule subunits are stable at cell temperature. 
C)  the concentration of water is much too small in cells. 
D)  A and B 
A)  covalent bonds linking macromolecule subunits are stable at cell pH. 
B)  covalent bonds linking macromolecule subunits are stable at cell temperature. 
C)  the concentration of water is much too small in cells. 
D)  A and B

Question 14

The oxygen atom of water is nucleophilic because

Accepted Answer

A)  it has a negative oxidation number. 
B)  it carries a partial positive charge. 
C)  it has two unshared pair of electrons. 
D)  it seeks electron-rich molecules. 
E)  All of the above 
A)  it has a negative oxidation number. 
B)  it carries a partial positive charge. 
C)  it has two unshared pair of electrons. 
D)  it seeks electron-rich molecules. 
E)  All of the above

Question 15

For a weak acid with a pKa = 6.5, the effective buffering range is usually considered to be

Accepted Answer

A)  pH 6 to pH 7. 
B)  pH 6.4 to pH 6.6. 
C)  pH 5.5 to pH 7.5. 
D)  dependent on the molarity of the acid. 
E)  B and C 
A)  pH 6 to pH 7. 
B)  pH 6.4 to pH 6.6. 
C)  pH 5.5 to pH 7.5. 
D)  dependent on the molarity of the acid. 
E)  B and C

Question 16

The strength of van der Waals forces between two molecules changes as the distance between them changes.

Accepted Answer

A) True 
 B)False

Question 17

Molecules that are both hydrophobic and hydrophilic are .

Accepted Answer

A)  amphipathic 
B)  amphoteric 
C)  bipolar 
D)  not possible 
A)  amphipathic 
B)  amphoteric 
C)  bipolar 
D)  not possible

Question 18

Synthetic compounds used as buffers are not as valuable for experiments as naturally occurring compounds used as buffers.

Accepted Answer

A) True 
 B)False

Question 19

In pure water hydronium ions are formed by attack of oxygen on a proton in an adjacent water molecule.

Accepted Answer

A)  ionic 
B)  nucleophilic 
C)  electrophilic 
D)  covalent 
A)  ionic 
B)  nucleophilic 
C)  electrophilic 
D)  covalent

Question 20

What is the maximum number of hydrogen bonds that one water molecule can have with neighboring water molecules?

Accepted Answer

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

Exam 2: Water

Blood pH is primarily regulated by

Oil and water do not form a solution due to .

The buffering capacity of a weak acid and its conjugate base is strongest when the pH = pKa.

A molecule or ion is said to be hydrated when it .

At the midpoint of a titration curve

Some ions such as thiocyanate that are poorly solvated in water and can enhance the solubility of nonpolar compounds in water by disordering the water molecules are called .

Water molecules that surround a less polar molecule in solution are immobile and ordered.

The H+ or H3O+ in cells is the same concentration as that of undissociated water.

The aggregation of nonpolar molecules or groups in water is thermodynamically due to the

Compounds that ionize when dissolved in water are called .

The ratio of the concentration of a over describes the proportions of forms of a weak acid necessary to satisfy the Henderson-Hasselbalch equation.

The water solubility of alcohols with a single hydroxyl group increases as a function of molecular weight.

Water is a nucleophile, yet it does not usually hydrolyze macromolecules in cells because

The oxygen atom of water is nucleophilic because

For a weak acid with a pKa = 6.5, the effective buffering range is usually considered to be

The strength of van der Waals forces between two molecules changes as the distance between them changes.

Molecules that are both hydrophobic and hydrophilic are .

Synthetic compounds used as buffers are not as valuable for experiments as naturally occurring compounds used as buffers.

In pure water hydronium ions are formed by attack of oxygen on a proton in an adjacent water molecule.

What is the maximum number of hydrogen bonds that one water molecule can have with neighboring water molecules?

Introduction to Biochemistry

Amino Acids and the Primary Structures of Proteins

Proteins: Three-Dimensional Structure and Function

Properties of Enzymes

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

Dna Replication, Repair, and Recombination

Transcription and Rna Processing

Protein Synthesis

Recombinant Dna Technology

Filters

The buffering capacity of a weak acid and its conjugate base is strongest when the pH = pK_a.

The H⁺or H₃O⁺ in cells is the same concentration as that of undissociated water.

For a weak acid with a pK_a= 6.5, the effective buffering range is usually considered to be