UNE Biochemistry Final Exam
Questions and All Correct Answers
2025-2026.
The glucose-alanine cycle is a method of transferring ammonia from the skeletal muscle to the
liver. In this process the non-toxic carrier of ammonia is which of the following compounds? -
Answer Alanine
Which of the following enzymes is correctly paired with its activator? - Answer N-
acetylglutamate synthetase; arginine
The urea cycle takes place in which of the following subcellular locations? - Answer the
cytosol and the mitochondria
Which of the following enzymes is regulated by N-acetylglutamate (NAGs)? - Answer CPS I
Which of the following enzymes is the regulatory step in the urea cycle? - Answer Carbamoyl
phosphate synthetase I (CPS I)
Which of the following statements is consistent with nitrogen transport in the fasted state? -
Answer The urea cycle will be active
A comatose infant is brought to the ER. In the course of the examination, plasma ammonia was
found to be elevated 20-fold over normal values. Urine orotic acid and uracil were both greater
than normal. A defect of which of the following enzymes is the most likely diagnosis? - Answer
Ornithine transcarbamoylase
Your patient presents with a deficiency of the enzyme that catalyzes synthesis of N-
acetylglutamate (NAGs). Which of the following would be a consequence of this deficiency in
the patient? - Answer Increased amino acids in the blood
The cellular uptake of LDL increases intracellular cholesterol levels. This has which of the
following impacts on de novo cholesterol synthesis? - Answer Increases degradation of
HMG-CoA reductase
Dietary cholesterol is primarily transported in the body by which of the following lipoproteins? -
Answer Chylomicron
,Secondary bile salts are generated by bacterial modification of primary bile salts in the intestinal
lumen. These modifications have which of the following impacts on bile salt solubility? - Answer
Decrease solubility
A 47-year-old male is prescribed a statin (HMG-CoA reductase inhibitor) to manage his elevated
LDL cholesterol. What is the initial mechanism of action for obtaining the desired effect in this
man? - Answer Decreasing hepatic cholesterol biosynthesis
A deficiency in the LDL receptor will result in an initial decrease in which of the following? -
Answer Intracellular cholesterol
A 45-year-old man has a mild heart attack and a history of vascular disease. He is placed on a
Mediterranean diet and statin drug therapy. Which of the following will be the most likely result
of this drug therapy? - Answer Low blood LDLs
A 45-year-old man is found to have an elevated serum triglycerides of > 730mg/dL. He tells you
he forgot to fast before his visit and he ate a full breakfast of bacon and eggs before the labs
were drawn. Which of the following lipoproteins would be the largest contributors to a
measurement of plasma triglycerides in this situation? - Answer Chylomicrons and VLDLs
In the reaction catalyzed by cholesterol ester transfer protein (CETP), the VLDL particle receives
which of the following compounds from HDL particles? - Answer Cholesterol-ester
In reverse cholesterol transport HDL interacts with the ABCA1 transporter to move cholesterol
from the cell to the HDL. This also requires the activity of which of the following enzyme? -
Answer Lecithin cholesterol acyltransferase (LCAT)
HDL particles interact with VLDL particles to exchange cholesterol ester for triacylglyerols.
Which of the following enzymes is responsible for this process? - Answer Cholesterol ester
transfer protein (CETP)
Which of the following is a major source of extracellular cholesterol for human tissues? -
Answer LDLs
An individual is suspected of having a deficiency in branched chain keto acid dehydrogenase.
Supplementation of which of the following vitamins or cofactors may help resolve this issue? -
Answer Thiamine
A 55-year old man presents to his primary care physician with bouts of dizziness and confusion.
He is diagnosed with hyperhomocysteinemia due to a deficiency of cystathionine-ß synthase. In
this individual which of the following amino acids could potentially become essential? - Answer
Cysteine
, Phenylketonuria can be caused by an enzymatic deficiency or it can present due to a deficiency
in which of the following required metabolic cofactors? - Answer Tetrahydrobiopterin (BH4)
A 17-year old female presents to her primary care and is diagnosed with a Vitamin B12
(cobalamin) deficiency. In this individual, which of the following reactions would be
compromised? - Answer Conversion of methyl malonyl-Co A to succinyl-CoA
A 15-year-old female presents to her pediatrician with concerns over her inability to sleep,
increased feelings of depression and generalized fatigue. A full laboratory work-up is ordered
and based on these findings she is diagnosed with a melatonin deficiency. Based on this
information, metabolism of which of the following amino acids is likely impaired? - Answer
Tryptophan
A 52-year- old male sought medical help complaining about progressive appearance of
hyperchromic (hyper pigmented) papules on the edge of the second finger of both hands. He
also complained about darkening of urine. Incisional biopsy of one of the spots on his hands and
urine sample tested positive for or homogentisic acid. Based on these findings a diagnosis of
alkaptonuria is made. This diagnosis is consistent with a deficiency in which of the following
enzymes? - Answer Homogentisate oxidase
Methotrexate is a potent anticancer agent that starves dividing cells of deoxyribonucleotides
through direct inhibition of which of the following processes? - Answer Metabolism of folic
acid
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? - Answer Elevated uric acid
Which of the following is the common intermediate for purine synthesis? - Answer Inosine
monophosphate
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? - Answer
Thioredoxin
In pyrimidine synthesis, carbamoyl phosphate synthetase II (CPSII) can be allosterically activated
by which of the following compounds? - Answer 5-phosphoribosyl 1-pyrophosphate (PRPP)
Questions and All Correct Answers
2025-2026.
The glucose-alanine cycle is a method of transferring ammonia from the skeletal muscle to the
liver. In this process the non-toxic carrier of ammonia is which of the following compounds? -
Answer Alanine
Which of the following enzymes is correctly paired with its activator? - Answer N-
acetylglutamate synthetase; arginine
The urea cycle takes place in which of the following subcellular locations? - Answer the
cytosol and the mitochondria
Which of the following enzymes is regulated by N-acetylglutamate (NAGs)? - Answer CPS I
Which of the following enzymes is the regulatory step in the urea cycle? - Answer Carbamoyl
phosphate synthetase I (CPS I)
Which of the following statements is consistent with nitrogen transport in the fasted state? -
Answer The urea cycle will be active
A comatose infant is brought to the ER. In the course of the examination, plasma ammonia was
found to be elevated 20-fold over normal values. Urine orotic acid and uracil were both greater
than normal. A defect of which of the following enzymes is the most likely diagnosis? - Answer
Ornithine transcarbamoylase
Your patient presents with a deficiency of the enzyme that catalyzes synthesis of N-
acetylglutamate (NAGs). Which of the following would be a consequence of this deficiency in
the patient? - Answer Increased amino acids in the blood
The cellular uptake of LDL increases intracellular cholesterol levels. This has which of the
following impacts on de novo cholesterol synthesis? - Answer Increases degradation of
HMG-CoA reductase
Dietary cholesterol is primarily transported in the body by which of the following lipoproteins? -
Answer Chylomicron
,Secondary bile salts are generated by bacterial modification of primary bile salts in the intestinal
lumen. These modifications have which of the following impacts on bile salt solubility? - Answer
Decrease solubility
A 47-year-old male is prescribed a statin (HMG-CoA reductase inhibitor) to manage his elevated
LDL cholesterol. What is the initial mechanism of action for obtaining the desired effect in this
man? - Answer Decreasing hepatic cholesterol biosynthesis
A deficiency in the LDL receptor will result in an initial decrease in which of the following? -
Answer Intracellular cholesterol
A 45-year-old man has a mild heart attack and a history of vascular disease. He is placed on a
Mediterranean diet and statin drug therapy. Which of the following will be the most likely result
of this drug therapy? - Answer Low blood LDLs
A 45-year-old man is found to have an elevated serum triglycerides of > 730mg/dL. He tells you
he forgot to fast before his visit and he ate a full breakfast of bacon and eggs before the labs
were drawn. Which of the following lipoproteins would be the largest contributors to a
measurement of plasma triglycerides in this situation? - Answer Chylomicrons and VLDLs
In the reaction catalyzed by cholesterol ester transfer protein (CETP), the VLDL particle receives
which of the following compounds from HDL particles? - Answer Cholesterol-ester
In reverse cholesterol transport HDL interacts with the ABCA1 transporter to move cholesterol
from the cell to the HDL. This also requires the activity of which of the following enzyme? -
Answer Lecithin cholesterol acyltransferase (LCAT)
HDL particles interact with VLDL particles to exchange cholesterol ester for triacylglyerols.
Which of the following enzymes is responsible for this process? - Answer Cholesterol ester
transfer protein (CETP)
Which of the following is a major source of extracellular cholesterol for human tissues? -
Answer LDLs
An individual is suspected of having a deficiency in branched chain keto acid dehydrogenase.
Supplementation of which of the following vitamins or cofactors may help resolve this issue? -
Answer Thiamine
A 55-year old man presents to his primary care physician with bouts of dizziness and confusion.
He is diagnosed with hyperhomocysteinemia due to a deficiency of cystathionine-ß synthase. In
this individual which of the following amino acids could potentially become essential? - Answer
Cysteine
, Phenylketonuria can be caused by an enzymatic deficiency or it can present due to a deficiency
in which of the following required metabolic cofactors? - Answer Tetrahydrobiopterin (BH4)
A 17-year old female presents to her primary care and is diagnosed with a Vitamin B12
(cobalamin) deficiency. In this individual, which of the following reactions would be
compromised? - Answer Conversion of methyl malonyl-Co A to succinyl-CoA
A 15-year-old female presents to her pediatrician with concerns over her inability to sleep,
increased feelings of depression and generalized fatigue. A full laboratory work-up is ordered
and based on these findings she is diagnosed with a melatonin deficiency. Based on this
information, metabolism of which of the following amino acids is likely impaired? - Answer
Tryptophan
A 52-year- old male sought medical help complaining about progressive appearance of
hyperchromic (hyper pigmented) papules on the edge of the second finger of both hands. He
also complained about darkening of urine. Incisional biopsy of one of the spots on his hands and
urine sample tested positive for or homogentisic acid. Based on these findings a diagnosis of
alkaptonuria is made. This diagnosis is consistent with a deficiency in which of the following
enzymes? - Answer Homogentisate oxidase
Methotrexate is a potent anticancer agent that starves dividing cells of deoxyribonucleotides
through direct inhibition of which of the following processes? - Answer Metabolism of folic
acid
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? - Answer Elevated uric acid
Which of the following is the common intermediate for purine synthesis? - Answer Inosine
monophosphate
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? - Answer
Thioredoxin
In pyrimidine synthesis, carbamoyl phosphate synthetase II (CPSII) can be allosterically activated
by which of the following compounds? - Answer 5-phosphoribosyl 1-pyrophosphate (PRPP)
