Question 1

Which of these noncovalent forces in biological systems is usually the strongest?

Accepted Answer

A) Hydrogen bonds. 
B) London dispersion forces. 
C) Hydrophobic interactions. 
D) Van der Waals forces. 
A) Hydrogen bonds. 
B) London dispersion forces. 
C) Hydrophobic interactions. 
D) Van der Waals forces.

Question 2

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

Question 3

In pure water,the concentration of H+ plus equals

Accepted Answer

A) 1 × 10-⁷ M. 
B) 1 × 10-¹⁴ M. 
C) 1 M. 
D) .07 M. 
A) 1 × 10-⁷ M. 
B) 1 × 10-¹⁴ M. 
C) 1 M. 
D) .07 M.

Question 4

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 5

An intermediate formed by the enzyme glutamine synthetase,gamma-glutamyl phosphate,is rapidly hydrolyzed by water if the enzyme is not around to protect it.

Accepted Answer

A) True 
 B)False

Question 6

What is the difference between a particle being hydrated versus being solvated?

Accepted Answer

A) A hydrated particle is surrounded by a shell of water.A solvated molecule is surrounded by a shell of solvent molecules,not necessarily water. 
B) The terms hydrated and solvated mean exactly the same thing. 
C) A hydrated particle has reacted with hydrogen.A solvated particle is dissolved in a solvent. 
D) The word hydrated is used only when the solute is an electrolyte. 
A) A hydrated particle is surrounded by a shell of water.A solvated molecule is surrounded by a shell of solvent molecules,not necessarily water. 
B) The terms hydrated and solvated mean exactly the same thing. 
C) A hydrated particle has reacted with hydrogen.A solvated particle is dissolved in a solvent. 
D) The word hydrated is used only when the solute is an electrolyte.

Question 7

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 8

Intracellular buffers include

Accepted Answer

A) proteins. 
B) inorganic phosphate. 
C) cellulose. 
D) Both A and B. 
E) A,B and C. 
A) proteins. 
B) inorganic phosphate. 
C) cellulose. 
D) Both A and B. 
E) A,B and C.

Question 9

The osmotic pressure of a 0.010 M sucrose (C₁₂H₂₂O₁₁)solution at 25°C is 0.24 atm.How does the osmotic pressure of a 0.010 M glucose (C₆H₁₂O₆)solution at 25°C compare to this? Note that neither solute is volatile or ionizable.

Accepted Answer

A) The glucose solution has a lower osmotic pressure because its molar mass is lower than sucrose. 
B) The glucose solution has a higher osmotic pressure because its molar mass is lower than sucrose. 
C) The osmotic pressures are equal because the solutions have the same molar concentration. 
D) Nothing can be said about the osmotic pressure of the glucose solution without more information. 
A) The glucose solution has a lower osmotic pressure because its molar mass is lower than sucrose. 
B) The glucose solution has a higher osmotic pressure because its molar mass is lower than sucrose. 
C) The osmotic pressures are equal because the solutions have the same molar concentration. 
D) Nothing can be said about the osmotic pressure of the glucose solution without more information.

Question 10

Salt bridges are often found on the surfaces of proteins where they are stabilized by water.

Accepted Answer

A) True 
 B)False

Question 11

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 12

A hydrated potassium ion is surrounded by a shell of water molecules oriented primarily with their oxygen atoms toward the potassium ion.

Accepted Answer

A) True 
 B)False

Question 13

When acid is added to pure water,Kw,the ion-product constant of water,changes.

Accepted Answer

A) True 
 B)False

Question 14

The pKa of lactic acid is 3.9.A lactate buffer will be useful from pH values

Accepted Answer

A) 3.5 through 4.4. 
B) 3.0 through 4.5. 
C) 2.9 through 4.9. 
D) 3.8 through 4.0. 
A) 3.5 through 4.4. 
B) 3.0 through 4.5. 
C) 2.9 through 4.9. 
D) 3.8 through 4.0.

Question 15

The three dimensional structure of most proteins is largely determined by

Accepted Answer

A) other proteins which fold them. 
B) weak noncovalent interactions. 
C) denaturation. 
D) hydrogen bonds. 
E) All of the above. 
A) other proteins which fold them. 
B) weak noncovalent interactions. 
C) denaturation. 
D) hydrogen bonds. 
E) All of the above.

Question 16

What is the concentration of hydroxide ion in an aqueous solution with an H+ concentration of 2 × 10-⁵ M?

Accepted Answer

A) 2 × 10⁹ M 
B) 2 × 10-¹⁹ M 
C) 2 × 10-¹ M 
D) 5 × 10-¹⁰ M 
E) Cannot calculate from the information given. 
A) 2 × 10⁹ M 
B) 2 × 10-¹⁹ M 
C) 2 × 10-¹ M 
D) 5 × 10-¹⁰ M 
E) Cannot calculate from the information given.

Question 17

Hydrophobic interactions are sometimes called "bonds",because each one is as strong as a covalent bond.

Accepted Answer

A) True 
 B)False

Question 18

Van der Waals forces are very strongly repulsive at short nuclear distances and very weak at long internuclear distances.

Accepted Answer

A) True 
 B)False

Question 19

Which statement is true about the ability of carbon to participate in hydrogen bonds in living organisms?

Accepted Answer

A) There are too many carbon atoms competing for the hydrogens in biomolecules to allow for the stable formation of hydrogen bonds. 
B) Carbon's electronegativity is too low to participate in hydrogen bonding. 
C) Most carbons in biomolecules are hydrogen bonded to water. 
D) Carbon is too large to participate in hydrogen bonding. 
A) There are too many carbon atoms competing for the hydrogens in biomolecules to allow for the stable formation of hydrogen bonds. 
B) Carbon's electronegativity is too low to participate in hydrogen bonding. 
C) Most carbons in biomolecules are hydrogen bonded to water. 
D) Carbon is too large to participate in hydrogen bonding.

Question 20

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.

Exam 2: Water

Which of these noncovalent forces in biological systems is usually the strongest?

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

In pure water,the concentration of H+ plus equals

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

An intermediate formed by the enzyme glutamine synthetase,gamma-glutamyl phosphate,is rapidly hydrolyzed by water if the enzyme is not around to protect it.

What is the difference between a particle being hydrated versus being solvated?

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

Intracellular buffers include

The osmotic pressure of a 0.010 M sucrose (C₁₂H₂₂O₁₁)solution at 25°C is 0.24 atm.How does the osmotic pressure of a 0.010 M glucose (C₆H₁₂O₆)solution at 25°C compare to this? Note that neither solute is volatile or ionizable.

Salt bridges are often found on the surfaces of proteins where they are stabilized by water.

Blood pH is primarily regulated by

A hydrated potassium ion is surrounded by a shell of water molecules oriented primarily with their oxygen atoms toward the potassium ion.

When acid is added to pure water,Kw,the ion-product constant of water,changes.

The pKa of lactic acid is 3.9.A lactate buffer will be useful from pH values

The three dimensional structure of most proteins is largely determined by

What is the concentration of hydroxide ion in an aqueous solution with an H+ concentration of 2 × 10-⁵ M?

Hydrophobic interactions are sometimes called "bonds",because each one is as strong as a covalent bond.

Van der Waals forces are very strongly repulsive at short nuclear distances and very weak at long internuclear distances.

Which statement is true about the ability of carbon to participate in hydrogen bonds in living organisms?

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

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 Atp Synthesis

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

DNA Replication, repair, and Recombination

Transcription and RNA Processing

Protein Synthesis

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