CHEM 1005 CORE EXAM TEST 2026 QUESTIONS AND
SOLUTIONS GRADED A+
✔✔Which of the following compounds or substrates is required for the synthesis of
tyrosine? (+ indicates the compound is required; - indicates the compound is not
required)
Tetrahydrofolate (THF) Tetrahydrobiopterin (BH4) Tryptophan Phenylalanine
1. + + + -
2. - + + -
3. + - - +
4. - + - + - ✔✔4. - + - +
✔✔An infant is normal at birth but becomes lethargic after several feedings. The
assigned nurse describes an unusual smell to the urine but is ignored. Infection (sepsis)
is suspected, and blood tests show normal white blood cell counts with a serum pH of
7.0. Evaluation for an inborn error of metabolism shows an abnormal amino acid
screen. The report states that branch-chain amino acids are strikingly elevated.
Elevation of which of the following amino acids would be consistent with the report? -
✔✔Isoleucine
✔✔S-adenosylmethionine (SAM) is synthesized from ATP and methionine. A deficiency
in which of the following enzymes would impair the production of SAM? - ✔✔Methionine
adenosyltransferase (MAT)
✔✔The regulation of PRPP synthetase is critical in the production of both purines and
pyrimidines. This enzyme is inhibited under which of the following conditions? -
✔✔When both GDP and ADP are elevated
✔✔The ribonucleotide reductase is important for converting ribose bases to the deoxy
form. This conversion is coupled with the oxidation of which of the following
compounds? - ✔✔Thioredoxin
✔✔Purine biosynthesis starts with the activation of a 5-carbon sugar. In this initial
reaction, ribose 5-phosphate is converted into which of the following compounds? -
✔✔PRPP (5- phosphoribosylpyrophosphate)
✔✔The conversion of ribose bases into deoxy-bases will be occurring under which of
the following conditions? - ✔✔When cells are proliferating
✔✔Which of the following enzymes is used directly in the synthesis of dTMP
(thymidine)? - ✔✔Thymidylate synthase
, ✔✔A 47-year-old man complains of pain in the joints of his left big toe, which are
obviously swollen and tender. The pain has been chronic but became intolerable the
day after Thanksgiving when he had a large meal and several glasses of red wine.
Based on this information a diagnosis of gout is made. Which of the following is involved
in the pathophysiology of this patient's condition? - ✔✔Elevated uric acid
✔✔Which of the following characteristics distinguish most RNA molecules from DNA? -
✔✔Uridine base on RNA, whereas a thymidine base on DNA
✔✔In pyrimidine synthesis, uridine triphosphate (UTP) can feedback and inhibit which
of the following enzymes? - ✔✔Carbamoyl phosphate synthase II
✔✔Homocystinuria can be caused by several different enzyme or vitamin deficiencies.
An elevation of homocysteine and a decrease in cysteine would most likely present due
to which of the following deficiencies? - ✔✔Loss of function of cystathionine-β synthase
✔✔You and a friend are being chased by a bear. Under these conditions levels of
epinephrine are increased due to metabolism of which of the following amino acids? -
✔✔Tyrosine
✔✔Which of the following amino acids is essential? - ✔✔Methiodine
✔✔A deficiency in B6 (pyridoxal phosphate) would negatively impact which of the
following pathways:
1. Metabolism of homocysteine to cysteine
2. Metabolism of phenylalanine to tyrosine
3. Conversion of methyl malonyl-CoA to succinyl-CoA - ✔✔1 only
✔✔Which of the following is the common intermediate for purine synthesis? -
✔✔Inosine monophosphate
✔✔Folate is an essential compound in the synthesis of nucleotides. All of the following
nucleotides require folate for synthesis except: - ✔✔CTP
✔✔In pyrimidine synthesis, carbamoyl phosphate synthetase II (CPSII) can be
allosterically activated by which of the following compounds? - ✔✔5-phosphoribosyl 1-
pyrophosphate (PRPP)
✔✔A 40-year-old male comes in to the doctor's office with severe pain in his big toe. He
is diagnosed with gout. Allopurinol is administered and this drug will inhibit which of the
following enzymes? - ✔✔Xanthine oxidase
SOLUTIONS GRADED A+
✔✔Which of the following compounds or substrates is required for the synthesis of
tyrosine? (+ indicates the compound is required; - indicates the compound is not
required)
Tetrahydrofolate (THF) Tetrahydrobiopterin (BH4) Tryptophan Phenylalanine
1. + + + -
2. - + + -
3. + - - +
4. - + - + - ✔✔4. - + - +
✔✔An infant is normal at birth but becomes lethargic after several feedings. The
assigned nurse describes an unusual smell to the urine but is ignored. Infection (sepsis)
is suspected, and blood tests show normal white blood cell counts with a serum pH of
7.0. Evaluation for an inborn error of metabolism shows an abnormal amino acid
screen. The report states that branch-chain amino acids are strikingly elevated.
Elevation of which of the following amino acids would be consistent with the report? -
✔✔Isoleucine
✔✔S-adenosylmethionine (SAM) is synthesized from ATP and methionine. A deficiency
in which of the following enzymes would impair the production of SAM? - ✔✔Methionine
adenosyltransferase (MAT)
✔✔The regulation of PRPP synthetase is critical in the production of both purines and
pyrimidines. This enzyme is inhibited under which of the following conditions? -
✔✔When both GDP and ADP are elevated
✔✔The ribonucleotide reductase is important for converting ribose bases to the deoxy
form. This conversion is coupled with the oxidation of which of the following
compounds? - ✔✔Thioredoxin
✔✔Purine biosynthesis starts with the activation of a 5-carbon sugar. In this initial
reaction, ribose 5-phosphate is converted into which of the following compounds? -
✔✔PRPP (5- phosphoribosylpyrophosphate)
✔✔The conversion of ribose bases into deoxy-bases will be occurring under which of
the following conditions? - ✔✔When cells are proliferating
✔✔Which of the following enzymes is used directly in the synthesis of dTMP
(thymidine)? - ✔✔Thymidylate synthase
, ✔✔A 47-year-old man complains of pain in the joints of his left big toe, which are
obviously swollen and tender. The pain has been chronic but became intolerable the
day after Thanksgiving when he had a large meal and several glasses of red wine.
Based on this information a diagnosis of gout is made. Which of the following is involved
in the pathophysiology of this patient's condition? - ✔✔Elevated uric acid
✔✔Which of the following characteristics distinguish most RNA molecules from DNA? -
✔✔Uridine base on RNA, whereas a thymidine base on DNA
✔✔In pyrimidine synthesis, uridine triphosphate (UTP) can feedback and inhibit which
of the following enzymes? - ✔✔Carbamoyl phosphate synthase II
✔✔Homocystinuria can be caused by several different enzyme or vitamin deficiencies.
An elevation of homocysteine and a decrease in cysteine would most likely present due
to which of the following deficiencies? - ✔✔Loss of function of cystathionine-β synthase
✔✔You and a friend are being chased by a bear. Under these conditions levels of
epinephrine are increased due to metabolism of which of the following amino acids? -
✔✔Tyrosine
✔✔Which of the following amino acids is essential? - ✔✔Methiodine
✔✔A deficiency in B6 (pyridoxal phosphate) would negatively impact which of the
following pathways:
1. Metabolism of homocysteine to cysteine
2. Metabolism of phenylalanine to tyrosine
3. Conversion of methyl malonyl-CoA to succinyl-CoA - ✔✔1 only
✔✔Which of the following is the common intermediate for purine synthesis? -
✔✔Inosine monophosphate
✔✔Folate is an essential compound in the synthesis of nucleotides. All of the following
nucleotides require folate for synthesis except: - ✔✔CTP
✔✔In pyrimidine synthesis, carbamoyl phosphate synthetase II (CPSII) can be
allosterically activated by which of the following compounds? - ✔✔5-phosphoribosyl 1-
pyrophosphate (PRPP)
✔✔A 40-year-old male comes in to the doctor's office with severe pain in his big toe. He
is diagnosed with gout. Allopurinol is administered and this drug will inhibit which of the
following enzymes? - ✔✔Xanthine oxidase
