Question 1

The pH of a sample of blood is 7.4,while gastric juice is pH 1.4.The blood sample has:

Accepted Answer

A) 0)189 times the [H+] as the gastric juice. 
B) 5)29 times lower [H+] than the gastric juice. 
C) 6 times lower [H+] than the gastric juice. 
D) 6000 times lower [H+] than the gastric juice. 
E) one million times lower [H+] than the gastric juice. 
A) 0)189 times the [H+] as the gastric juice. 
B) 5)29 times lower [H+] than the gastric juice. 
C) 6 times lower [H+] than the gastric juice. 
D) 6000 times lower [H+] than the gastric juice. 
E) one million times lower [H+] than the gastric juice. E

Question 2

You have just made a solution by combining 50 mL of a 0.1 M sodium acetate solution with 150 mL of 1 M acetic acid (pKa = 4.7).What is the pH of the resulting solution?

Accepted Answer

pH = pK_a + log = 4.7 + log (5/150) = 4.7 - 1.48 = 3.22

Question 3

In proteins,the amino acid histidine (His)plays an important role in many biological reactions.The pKa for the protonation of His to form HisH+ = 6.0.When pH = 7.0,what is the fraction of total histidine that will be in the HisH+ form?

Accepted Answer

Use the Henderson-Hasselbalch equation to determine the ratio of [His] to [HisH⁺]. To determine the fraction of the total in the HisH+ form, [His]_total = [His] + [HisH+],

Question 4

Draw the titration curve for a weak acid,HA,whose pKa is 3.2.Label the axes properly.Indicate with an arrow where on the curve the ratio of salt (A-)to acid (HA)is 3:1.What is the pH at this point?

Accepted Answer

The plot of pH versus added base should

Question 5

Give the general Henderson-Hasselbalch equation and sketch the plot it describes (pH against amount of NaOH added to a weak acid).On your curve,label the pKa for the weak acid and indicate the region in which the buffering capacity of the system is greatest.

Accepted Answer

The inflection point,which occurs when t

Question 6

Explain with an appropriate diagram why amphipathic molecules tend to form micelles in water.What force drives micelle formation?

Accepted Answer

Micelle formation minimizes the area of

Question 7

What is the pH of a solution containing 0.2 M acetic acid (pKa = 4.7)and 0.1 M sodium acetate?

Accepted Answer

pH = pK_a + log @#IMG-DLM& = 4.7

Question 8

(a)Briefly define "isotonic," "hypotonic," and "hypertonic" solutions.
(b)Describe what happens when a cell is placed in each of these types of solutions.

Accepted Answer

(a)An isotonic solution has the same osm

Question 9

Osmosis is movement of a:

Accepted Answer

A) charged solute molecule (ion)across a membrane. 
B) gas molecule across a membrane. 
C) nonpolar solute molecule across a membrane. 
D) polar solute molecule across a membrane. 
E) water molecule across a membrane. 
A) charged solute molecule (ion)across a membrane. 
B) gas molecule across a membrane. 
C) nonpolar solute molecule across a membrane. 
D) polar solute molecule across a membrane. 
E) water molecule across a membrane.

Question 10

Which of the following properties of water does not contribute to the fitness of the aqueous environment for living organisms?

Accepted Answer

A) Cohesion of liquid water due to hydrogen bonding 
B) High heat of vaporization 
C) High specific heat 
D) The density of water is greater than the density of ice 
E) The very low molecular weight of water 
A) Cohesion of liquid water due to hydrogen bonding 
B) High heat of vaporization 
C) High specific heat 
D) The density of water is greater than the density of ice 
E) The very low molecular weight of water

Question 11

Which of the following statements about buffers is true?

Accepted Answer

A) A buffer composed of a weak acid of pKa = 5 is stronger at pH 4 than at pH 6. 
B) At pH values lower than the pKa,the salt concentration is higher than that of the acid. 
C) The pH of a buffered solution remains constant no matter how much acid or base is added to the solution. 
D) The strongest buffers are those composed of strong acids and strong bases. 
E) When pH = pKa,the weak acid and salt concentrations in a buffer are equal. 
A) A buffer composed of a weak acid of pKa = 5 is stronger at pH 4 than at pH 6. 
B) At pH values lower than the pKa,the salt concentration is higher than that of the acid. 
C) The pH of a buffered solution remains constant no matter how much acid or base is added to the solution. 
D) The strongest buffers are those composed of strong acids and strong bases. 
E) When pH = pKa,the weak acid and salt concentrations in a buffer are equal.

Question 12

Explain the fact that ethanol (CH3CH2OH)is more soluble in water than is ethane (CH3CH3).

Accepted Answer

Ethanol can form hydrogen bonds with wat

Question 13

For a weak acid with a pKa of 6.0,show how you would calculate the ratio of acid to salt at pH 5.

Accepted Answer

Question 14

Suppose you have just added 100 mL of a solution containing 0.5 mol of acetic acid per liter to 400 mL of 0.5 M NaOH.What is the final pH? (The pKa of acetic acid is 4.7. )

Accepted Answer

Addition of 200 mmol of NaOH (400 mL *0

Question 15

A compound is known to have a free amino group with a pKa of 8.8,and one other ionizable group with a pKa between 5 and 7.To 100 mL of a 0.2 M solution of this compound at pH 8.2 was added 40 mL of a solution of 0.2 M hydrochloric acid.The pH changed to 6.2.The pKa of the second ionizable group is:

Accepted Answer

A) The pH cannot be determined from this information. 
B) 5.4. 
C) 5.6. 
D) 6.0. 
E) 6.2. 
A) The pH cannot be determined from this information. 
B) 5.4. 
C) 5.6. 
D) 6.0. 
E) 6.2.

Question 16

Which of the following is true about the properties of aqueous solutions?

Accepted Answer

A) A pH change from 5.0 to 6.0 reflects an increase in the hydroxide ion concentration ([OH-])of 20%. 
B) A pH change from 8.0 to 6.0 reflects a decrease in the proton concentration ([H+])by a factor of 100. 
C) Charged molecules are generally insoluble in water. 
D) Hydrogen bonds form readily in aqueous solutions. 
E) The pH can be calculated by adding 7 to the value of the pOH. 
A) A pH change from 5.0 to 6.0 reflects an increase in the hydroxide ion concentration ([OH-])of 20%. 
B) A pH change from 8.0 to 6.0 reflects a decrease in the proton concentration ([H+])by a factor of 100. 
C) Charged molecules are generally insoluble in water. 
D) Hydrogen bonds form readily in aqueous solutions. 
E) The pH can be calculated by adding 7 to the value of the pOH.

Question 17

If ice were denser than water,how would that affect life on earth?

Accepted Answer

Ice that formed at the surface of bodies

Question 18

H+ + HCO3- $\rightleftarrows$ H2CO3 $\rightleftarrows$CO2 + H2O
Severe diarrhea is accompanied by a loss of HCO3-.If untreated,will the condition result in acidosis or alkalosis? Use the bicarbonate buffer system given in the scheme above and Le Chatelier's Principle to explain your answer.

Accepted Answer

Acidosis.The removal of HCO<su

Question 19

A hydronium ion:

Accepted Answer

A) has the structure H3O+. 
B) is a hydrated hydrogen ion. 
C) is a hydrated proton. 
D) is the usual form of one of the dissociation products of water in solution. 
E) All of the above are true. 
A) has the structure H3O+. 
B) is a hydrated hydrogen ion. 
C) is a hydrated proton. 
D) is the usual form of one of the dissociation products of water in solution. 
E) All of the above are true.

Question 20

Hydrophobic interactions make important energetic contributions to:

Accepted Answer

A) binding of a hormone to its receptor protein. 
B) enzyme-substrate interactions. 
C) membrane structure. 
D) three-dimensional folding of a polypeptide chain. 
E) All of the above are true. 
A) binding of a hormone to its receptor protein. 
B) enzyme-substrate interactions. 
C) membrane structure. 
D) three-dimensional folding of a polypeptide chain. 
E) All of the above are true.

Exam 2: Water

The pH of a sample of blood is 7.4,while gastric juice is pH 1.4.The blood sample has:

You have just made a solution by combining 50 mL of a 0.1 M sodium acetate solution with 150 mL of 1 M acetic acid (pKa = 4.7).What is the pH of the resulting solution?

In proteins,the amino acid histidine (His)plays an important role in many biological reactions.The pKa for the protonation of His to form HisH+ = 6.0.When pH = 7.0,what is the fraction of total histidine that will be in the HisH+ form?

Draw the titration curve for a weak acid,HA,whose pKa is 3.2.Label the axes properly.Indicate with an arrow where on the curve the ratio of salt (A-)to acid (HA)is 3:1.What is the pH at this point?

Give the general Henderson-Hasselbalch equation and sketch the plot it describes (pH against amount of NaOH added to a weak acid).On your curve,label the pKa for the weak acid and indicate the region in which the buffering capacity of the system is greatest.

Explain with an appropriate diagram why amphipathic molecules tend to form micelles in water.What force drives micelle formation?

What is the pH of a solution containing 0.2 M acetic acid (pKa = 4.7)and 0.1 M sodium acetate?

(a)Briefly define "isotonic," "hypotonic," and "hypertonic" solutions. (b)Describe what happens when a cell is placed in each of these types of solutions.

Osmosis is movement of a:

Which of the following properties of water does not contribute to the fitness of the aqueous environment for living organisms?

Which of the following statements about buffers is true?

Explain the fact that ethanol (CH3CH2OH)is more soluble in water than is ethane (CH3CH3).

For a weak acid with a pKa of 6.0,show how you would calculate the ratio of acid to salt at pH 5.

Suppose you have just added 100 mL of a solution containing 0.5 mol of acetic acid per liter to 400 mL of 0.5 M NaOH.What is the final pH? (The pKa of acetic acid is 4.7. )

A compound is known to have a free amino group with a pKa of 8.8,and one other ionizable group with a pKa between 5 and 7.To 100 mL of a 0.2 M solution of this compound at pH 8.2 was added 40 mL of a solution of 0.2 M hydrochloric acid.The pH changed to 6.2.The pKa of the second ionizable group is:

Which of the following is true about the properties of aqueous solutions?

If ice were denser than water,how would that affect life on earth?

A hydronium ion:

Hydrophobic interactions make important energetic contributions to:

The Foundations of Biochemistry

Amino Acids, peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

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You have just made a solution by combining 50 mL of a 0.1 M sodium acetate solution with 150 mL of 1 M acetic acid (pK_a = 4.7).What is the pH of the resulting solution?

In proteins,the amino acid histidine (His)plays an important role in many biological reactions.The pK_a for the protonation of His to form HisH⁺ = 6.0.When pH = 7.0,what is the fraction of total histidine that will be in the HisH⁺ form?

Draw the titration curve for a weak acid,HA,whose pK_a is 3.2.Label the axes properly.Indicate with an arrow where on the curve the ratio of salt (A^-)to acid (HA)is 3:1.What is the pH at this point?

Give the general Henderson-Hasselbalch equation and sketch the plot it describes (pH against amount of NaOH added to a weak acid).On your curve,label the pK_a for the weak acid and indicate the region in which the buffering capacity of the system is greatest.

What is the pH of a solution containing 0.2 M acetic acid (pK_a = 4.7)and 0.1 M sodium acetate?

Explain the fact that ethanol (CH₃CH₂OH)is more soluble in water than is ethane (CH₃CH₃).

For a weak acid with a pK_a of 6.0,show how you would calculate the ratio of acid to salt at pH 5.

Suppose you have just added 100 mL of a solution containing 0.5 mol of acetic acid per liter to 400 mL of 0.5 M NaOH.What is the final pH? (The pK_a of acetic acid is 4.7. )