Biology: Midterm Exam
1. A patient with poorly controlled Type I diabetes has blood drawn and finds that the pH of his blood is 7.1. The normal pH of blood is 7.4. The patient's blood [H+] is A) one fourth normal B) one third normal C) half normal D) twice normal E) three times normal
2. The Henderson-Hasselbalch equation:
A) allows the graphic determination of the molecular weight of a weak acid from its pH alone. B) does not explain the behavior of di- or tri-basic weak acids C) employs the same value for pKa for all weak acids. D) is equally useful with solutions of acetic acid and of hydrochloric acid. E) relates the pH of a solution to the pKa and the concentrations of the conjugate acid/base pair.
3. A 1.0 M solution of a compound with 2 ionizable groups (pKa’s = 6.2 and 9.5; 100 mL total) has a pH of 6.8. If a biochemist adds 60 mL of 1.0 M HCl to this solution, the solution will change to pH:
A) 5.60 B) 4.90 C) 6.13 D) 9.32 E) The pH cannot be determined from this information.
4. When oxygen binds to a heme-containing protein, two coordination bonds of Fe2+ interact with:
A) one O atom and one Lysine molecule in the globin subunit. B) one O2 molecule and proximal Histidine F8 of the globin subunit. C) one O2 molecule and distal Histidine E7 of the globin subunit. D) two O atoms. E) two O2 molecules.
5. Which of the following statements about cystine is correct?
A) Cystine forms when the —CH2—SH R group is oxidized to form a —CH2—S—S—CH2— disulfide bridge between two cysteines. B) Cystine is an example of a nonstandard amino acid, derived by linking two standard amino acids. C) Cystine is formed by the oxidation of the carboxylic acid group on cysteine. D) Cystine is formed through a peptide linkage between two cysteines. E) Two cystines are released when a —CH2—S—S—CH2— disulfide bridge is reduced to —CH2—SH.
6. In the binding of oxygen to
2. The Henderson-Hasselbalch equation:
A) allows the graphic determination of the molecular weight of a weak acid from its pH alone. B) does not explain the behavior of di- or tri-basic weak acids C) employs the same value for pKa for all weak acids. D) is equally useful with solutions of acetic acid and of hydrochloric acid. E) relates the pH of a solution to the pKa and the concentrations of the conjugate acid/base pair.
3. A 1.0 M solution of a compound with 2 ionizable groups (pKa’s = 6.2 and 9.5; 100 mL total) has a pH of 6.8. If a biochemist adds 60 mL of 1.0 M HCl to this solution, the solution will change to pH:
A) 5.60 B) 4.90 C) 6.13 D) 9.32 E) The pH cannot be determined from this information.
4. When oxygen binds to a heme-containing protein, two coordination bonds of Fe2+ interact with:
A) one O atom and one Lysine molecule in the globin subunit. B) one O2 molecule and proximal Histidine F8 of the globin subunit. C) one O2 molecule and distal Histidine E7 of the globin subunit. D) two O atoms. E) two O2 molecules.
5. Which of the following statements about cystine is correct?
A) Cystine forms when the —CH2—SH R group is oxidized to form a —CH2—S—S—CH2— disulfide bridge between two cysteines. B) Cystine is an example of a nonstandard amino acid, derived by linking two standard amino acids. C) Cystine is formed by the oxidation of the carboxylic acid group on cysteine. D) Cystine is formed through a peptide linkage between two cysteines. E) Two cystines are released when a —CH2—S—S—CH2— disulfide bridge is reduced to —CH2—SH.
6. In the binding of oxygen to