BIOCHEMISTRY CONCEPTS AND
CONNECTIONS SECOND EDITION DEAN
APPLING PRACTICE TEST 2026
COMPREHENSIVE QUESTIONS AND
SOLUTIONS GRADED A+
⩥ Protein biosynthesis uses only ________
.L-amino acids
R-amino acids
D-amino acids
S-amino acids
L-amino acids.
Answer: L-amino acids
⩥ All amino acids have a chiral α-carbon EXCEPT ________.
Tryptophan
Proline
Alanine
Glycine.
Answer: Glycine
,A key feature of amino acids is that the α carbon is chiral. When a
carbon atom is bound to four unique groups, it creates a chiral center
(also known as a stereocenter).
⩥ The side chain of ________ has a pKa in the physiological pH range
and is therefore often involved in proton transfer during enzymatic
catalysis
.Arg
His
Glu
Asp
His.
Answer: His (histidine)
Histidine is an α-amino acid involved in the biosynthesis of proteins.
The structure of histidine includes an α-amino acid, a carboxylic acid
group, and an imidazole side chain. Histidine was initially thought to be
essential only for infants; however, it has since been found to be
essential for adults too.
⩥ At physiological pH, the carboxylic acid group of an amino acid will
be ________, while the amino group will be ________, yielding the
zwitterion form.
deprotonated, protonated
,protonated, protonated
deprotonated, deprotonated
protonated, deprotonated.
Answer: deprotonated, protonated
⩥ Which of the following modified amino acids is incorporated during
translation rather than being modified post-translationally?
Selenocysteine
N-ε-acetyllysine
γ-carboxyglutamate
Phosphoserine.
Answer: Selenocysteine
⩥ Proteins have what charge on their carboxyl terminals at physiological
pH?Positive
Zero
Negative
Not enough information to determine.
Answer: Negative
⩥ If the R group of an amino acid is -CH3, then the name of this
compound is ________.
, Alanine
Isoleucine
3-methyl amino acid
3-aminopropanoic acid.
Answer: Alanine
⩥ Amino acids with non-ionizable side chains are zwitterions when they
are ________.In alkaline solutions only
At physiological pH,
pH = 7.4In acidic solutions only
In any solution
At physiological pH, pH = 7.4.
Answer: At physiological pH, pH = 7.4
⩥ At neutral pH, the net charge of serine is ________.
Negative
Zero
Positive
None of the above.
Answer: Zero
CONNECTIONS SECOND EDITION DEAN
APPLING PRACTICE TEST 2026
COMPREHENSIVE QUESTIONS AND
SOLUTIONS GRADED A+
⩥ Protein biosynthesis uses only ________
.L-amino acids
R-amino acids
D-amino acids
S-amino acids
L-amino acids.
Answer: L-amino acids
⩥ All amino acids have a chiral α-carbon EXCEPT ________.
Tryptophan
Proline
Alanine
Glycine.
Answer: Glycine
,A key feature of amino acids is that the α carbon is chiral. When a
carbon atom is bound to four unique groups, it creates a chiral center
(also known as a stereocenter).
⩥ The side chain of ________ has a pKa in the physiological pH range
and is therefore often involved in proton transfer during enzymatic
catalysis
.Arg
His
Glu
Asp
His.
Answer: His (histidine)
Histidine is an α-amino acid involved in the biosynthesis of proteins.
The structure of histidine includes an α-amino acid, a carboxylic acid
group, and an imidazole side chain. Histidine was initially thought to be
essential only for infants; however, it has since been found to be
essential for adults too.
⩥ At physiological pH, the carboxylic acid group of an amino acid will
be ________, while the amino group will be ________, yielding the
zwitterion form.
deprotonated, protonated
,protonated, protonated
deprotonated, deprotonated
protonated, deprotonated.
Answer: deprotonated, protonated
⩥ Which of the following modified amino acids is incorporated during
translation rather than being modified post-translationally?
Selenocysteine
N-ε-acetyllysine
γ-carboxyglutamate
Phosphoserine.
Answer: Selenocysteine
⩥ Proteins have what charge on their carboxyl terminals at physiological
pH?Positive
Zero
Negative
Not enough information to determine.
Answer: Negative
⩥ If the R group of an amino acid is -CH3, then the name of this
compound is ________.
, Alanine
Isoleucine
3-methyl amino acid
3-aminopropanoic acid.
Answer: Alanine
⩥ Amino acids with non-ionizable side chains are zwitterions when they
are ________.In alkaline solutions only
At physiological pH,
pH = 7.4In acidic solutions only
In any solution
At physiological pH, pH = 7.4.
Answer: At physiological pH, pH = 7.4
⩥ At neutral pH, the net charge of serine is ________.
Negative
Zero
Positive
None of the above.
Answer: Zero
