MCAT Organic Chemistry Review

Nitrogen- and Phosphorus-Containing Compounds

Practice Questions

1.    Which of the following amino acids does not have an L-enantiomer?

1.    Cysteine

2.    Threonine

3.    Glutamic acid

4.    Glycine

2.    Which of the following would be formed if methyl bromide were reacted with phthalimide and followed by hydrolysis with an aqueous base?

1.    C2H5NH2

2.    CH3NH2

3.    (C2H5)3N

4.    (CH3)4N+Br

3.    Which of the following amino acids contain(s) sulfur?

1.    Cysteine

2.    Serine

3.    Methionine

1.    I only

2.    I and III only

3.    II and III only

4.    I, II, and III

4.    Nylon, a polyamide, is produced from hexanediamine and a substance X. This substance X is most probably a(n):

1.    amine.

2.    carboxylic acid.

3.    ketone.

4.    alcohol.

5.    Intermediates in the Strecker synthesis include all of the following nitrogen-containing functional groups EXCEPT a(n):

1.    nitrile.

2.    imine.

3.    amide.

4.    amine.

6.    A biochemist is synthesizing valine, shown below, using the Strecker synthesis. Which of the following carbonyl-containing compounds would be an appropriate starting reactant in this synthesis?

1.    2-Propanone

2.    Propanal

3.    2-Methylpropanal

4.    Butanal

7.    Why is the C–N bond of an amide planar?

1.    It has partial double-bond character.

2.    It is sp3-hybridized.

3.    It has some sp2 character.

1.    I only

2.    II only

3.    I and II only

4.    I and III only

8.    Which of the primary methods of amino acid synthesis results in an optically active solution?

1.    The Strecker synthesis only

2.    The Gabriel synthesis only

3.    Both the Strecker and Gabriel syntheses

4.    Neither the Strecker nor the Gabriel syntheses

9.    During the Gabriel synthesis, phthalimide serves as the:

1.    nucleophile.

2.    base.

3.    leaving group.

4.    electrophile.

10.Each of the following reaction types occurs during the Gabriel synthesis EXCEPT:

1.    decarboxylation.

2.    nucleophilic substitution.

3.    dehydration.

4.    hydrolysis.

11.At physiological pH, which two forms of phosphoric acid have the highest concentrations?

1.    H3PO4 and H2PO4

2.    H2PO4 and HPO42−

3.    HPO42− and PO43−

4.    PO43− and H3PO4

12.In aqueous solution, pyrophosphate will likely:

1.    form insoluble complexes.

2.    be stable and inert.

3.    degrade into inorganic phosphate.

4.    decrease the polarity of the solvent.

13.What would be the charge of aspartic acid at pH 7?

1.    Neutral

2.    Negative

3.    Positive

4.    There is not enough information to answer the question.

14.When a bond is created between two nucleotide triphosphates in DNA synthesis, the small molecule released from this reaction is:

1.    pyrophosphate.

2.    inorganic phosphate.

3.    ATP.

4.    organic phosphate.

15.The hydrogens of phosphoric acid have pKa values that:

1.    allow high buffering capacity over a small pH range.

2.    allow moderate buffering capacity over a large pH range.

3.    allow low buffering capacity over a small pH range.

4.    do not allow buffering.