Biochem Practice Exam 1

Which of the following is a polymer derived from glucose?

A) cellulose

Which of the following acids or bases is least likely to be encountered in a biochemical setting?

A) nitric acid

Of Koshland's "pillars of life," which deals specifically with the structure and function of DNA?

A)program

Citric acid is a triprotic acid with three carboxylic acid groups having pKa values of 3.1, 4.8, and 6.4. If a solution of citric acid has a pH of 5.5, what can be said about the predominant protonation state of the citric acid?

B) 2 carboxylic acid groups are deprotonated, 1 is protonated

Given the pKa values for phosphoric acid of 2.14, 6.86 and 12.4, what is the ratio of HPO42-/H2PO4- in a typical muscle cell where the pH is 7.2?

B) 2.2

Formic acid is the active agent in an ant bite. What is the ratio of base/acid for formic acid (pKa 3.9) in the blood stream at pH 7.4?

B) 3.16 103

You have been asked to determine the pKa of an unknown acid. In a solution at pH 7.0, you find that 24% of the acid is in its deprotonated form. What is the pKa of the acid?

B) 7.5

The genetic information of viruses is contained within __________ .

B) DNA or RNA

Which of the following is the conjugate acid of hydrogen phosphate, HPO42-?

B) H2PO4-

Which of the following is the most likely noncovalent interaction observed between a carboxylic acid and an alcohol?

B) charge-dipole interaction

Which of the following represents the breaking of a noncovalent interaction?

B) dissolving of salt crystals

Prior to 1926, the source of biological catalysis was postulated to be possessed by "ferments" which today are called _______.

B) nucleic acids

The synthesis of which molecule is considered by many to be the root of biochemistry since it was the first synthesis of a biological molecule from non-biological precursors?

B) urea

Which of the following best describes homeostasis?

B)a non-equilibrium steady state

Which of the following elements is considered a second tier biochemical element meaning that it is less abundant than first tier elements but still required for life in all organisms?

C) P

Given the structure of a glucose molecule, which of the following explains the hydrogen bonding between glucose and water?

C) each glucose molecule could H-bond with as many as 17 water molecules

Which of the following best explains the hydrogen bonding that occurs in water?

C) glutamic acid

Of the following biomolecules, which is found only in a monomeric form as opposed to a polymeric form?

C) lipids

Originally, nucleic acids were thought to serve what role within a cell?

C) structural

Which of the following atoms could interact through a hydrogen bond?

C) the hydrogen of an amine and the oxygen of an alcohol

Which of the following would likely form micelles in an aqueous solution?

D) dodecanoic acid

Which of the following macromolecules is considered a homopolymer?

D) starch

) In the following titration curve, what does the inflection point represent?

E) all of the above

Which of the following is a role played by proteins?

E) all of the above

What functional groups are found in the following molecule?

E) carboxylic acid, hemiacetal, amine and alcohol

If gastric juice has a pH of about 1.5, which of the following would be predominantly deprotonated in the stomach?

E) hydrochloric acid (pKa = -6)

Since pKa = -log Ka, which of the following is a correct statement?

E) none of the above