CHEM 1005 UPDATED EXAM SCRIPT QUESTIONS AND
SOLUTIONS GRADED A+
✔✔which of the following is the regulatory enzyme for fatty acid synthesis? - ✔✔acetyl-
CoA carboxylase
✔✔bile salts are synthesized from cholesterol and are used for the emulsification of
dietary lipids. what is the primary fate of bile salts during digestion? - ✔✔they are
reabsorbed in the ileum
✔✔elevated cholesterol can enhance bile acid synthesis through which of the following
mechanisms? - ✔✔increasing the activity of 7 a-hydroxylase
✔✔a 55 year old male is diagnosed with type 2 diabetes and his current presentation is
consistent with a lack of insulin production. Serum levels of free fatty acids were
elevated in this individual primarily due to an increased activity of which of the following
enzymes? - ✔✔hormone sensitive lipase
✔✔short chain fatty acids and medium chain fatty acids enter mitochondria by -
✔✔diffusion
✔✔the interaction of chylomicrons with lipoprotein lipase is stimulated by which of the
following apoproteins? - ✔✔ApoCII
✔✔which of the following best describes the mechanism by which cholesterol is
eliminated - ✔✔cholesterol is used to synthesize secondary bile acids that are
eliminated in the feces
✔✔which of the following enzymes is regulated by N-acetyl glutamate ? - ✔✔carbamoyl
phosphate synthetase I
✔✔Which of the following statements is consistent with protein catabolism in the fed
state? - ✔✔high levels of arginine will stimulate the activity of urea synthesis
✔✔which of the following amino acids has a nitrogen in its side chain AND is an
intermediate of the urea cycle? - ✔✔arginine
✔✔a deficiency in the following enzymes will not result in an increase in orotic acid? -
✔✔N-acetyl glutamate synthetase
✔✔the transamination of all amino acids requires which of the following cofactors? -
✔✔pyridoxal phosphate
, ✔✔a comatose infant is brought to the emergency department. 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 most likely diagnosis - ✔✔ornithine transcarbamylase
✔✔a reaction of ammonia with a-ketoglutarate is catalyzed by ___ and requires ___ as
a reactant - ✔✔glutamate dehydrogenase; NADH or NADPH
✔✔select the choice that correctly indicates the proper sequence of the three stages of
urea biosynthesis leading to the urea cycle - ✔✔transamination -> oxidative
deamination of glutamate -> ammonia transport
✔✔nitrogen from amino acid metabolism is incorporated into all of the following
compounds except - ✔✔cholesterol
✔✔in the case of a deficiency in phenylalanine hydroxylase which of the following
amino acids will become essential? - ✔✔tyrosine
✔✔which of the following cofactors or vitamins is required for the conversion of
homocysteine to cysteine? - ✔✔pyridoxal phosphate
✔✔supplementation of which of the following cofacors/coenzymes may assist in the
activity of the branched-chain ketoacid dehydrogenase? - ✔✔thiamine
✔✔a 15 year old female is diagnosed with a melatonin deficiency. Based on this
information, metabolism of which of the following amino acids is likely impaired? -
✔✔tryptophan
✔✔a 55 year old man is diagnosed with hyperhomocysteinemia due to a deficiency in
cystathionine-B synthase. In this individual which of the following amino acids could
potentially become essential? - ✔✔cysteine
✔✔hyperpigmentation disorder is primarily due to deficient metabolism of which of the
following amino acids? - ✔✔tyrosine
✔✔serotonin is synthesized from which of the following amino acids? - ✔✔tryptophan
✔✔which of the following is the regulatory enzyme in pyrimidine synthesis? -
✔✔carbamoyl phosphate synthetase II
✔✔methotrexate is a potent anticancer agent that starves dividing cells of
deoxyribonucleotides through direct inhibition of which of the following processes? -
✔✔metabolism of folic acid
SOLUTIONS GRADED A+
✔✔which of the following is the regulatory enzyme for fatty acid synthesis? - ✔✔acetyl-
CoA carboxylase
✔✔bile salts are synthesized from cholesterol and are used for the emulsification of
dietary lipids. what is the primary fate of bile salts during digestion? - ✔✔they are
reabsorbed in the ileum
✔✔elevated cholesterol can enhance bile acid synthesis through which of the following
mechanisms? - ✔✔increasing the activity of 7 a-hydroxylase
✔✔a 55 year old male is diagnosed with type 2 diabetes and his current presentation is
consistent with a lack of insulin production. Serum levels of free fatty acids were
elevated in this individual primarily due to an increased activity of which of the following
enzymes? - ✔✔hormone sensitive lipase
✔✔short chain fatty acids and medium chain fatty acids enter mitochondria by -
✔✔diffusion
✔✔the interaction of chylomicrons with lipoprotein lipase is stimulated by which of the
following apoproteins? - ✔✔ApoCII
✔✔which of the following best describes the mechanism by which cholesterol is
eliminated - ✔✔cholesterol is used to synthesize secondary bile acids that are
eliminated in the feces
✔✔which of the following enzymes is regulated by N-acetyl glutamate ? - ✔✔carbamoyl
phosphate synthetase I
✔✔Which of the following statements is consistent with protein catabolism in the fed
state? - ✔✔high levels of arginine will stimulate the activity of urea synthesis
✔✔which of the following amino acids has a nitrogen in its side chain AND is an
intermediate of the urea cycle? - ✔✔arginine
✔✔a deficiency in the following enzymes will not result in an increase in orotic acid? -
✔✔N-acetyl glutamate synthetase
✔✔the transamination of all amino acids requires which of the following cofactors? -
✔✔pyridoxal phosphate
, ✔✔a comatose infant is brought to the emergency department. 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 most likely diagnosis - ✔✔ornithine transcarbamylase
✔✔a reaction of ammonia with a-ketoglutarate is catalyzed by ___ and requires ___ as
a reactant - ✔✔glutamate dehydrogenase; NADH or NADPH
✔✔select the choice that correctly indicates the proper sequence of the three stages of
urea biosynthesis leading to the urea cycle - ✔✔transamination -> oxidative
deamination of glutamate -> ammonia transport
✔✔nitrogen from amino acid metabolism is incorporated into all of the following
compounds except - ✔✔cholesterol
✔✔in the case of a deficiency in phenylalanine hydroxylase which of the following
amino acids will become essential? - ✔✔tyrosine
✔✔which of the following cofactors or vitamins is required for the conversion of
homocysteine to cysteine? - ✔✔pyridoxal phosphate
✔✔supplementation of which of the following cofacors/coenzymes may assist in the
activity of the branched-chain ketoacid dehydrogenase? - ✔✔thiamine
✔✔a 15 year old female is diagnosed with a melatonin deficiency. Based on this
information, metabolism of which of the following amino acids is likely impaired? -
✔✔tryptophan
✔✔a 55 year old man is diagnosed with hyperhomocysteinemia due to a deficiency in
cystathionine-B synthase. In this individual which of the following amino acids could
potentially become essential? - ✔✔cysteine
✔✔hyperpigmentation disorder is primarily due to deficient metabolism of which of the
following amino acids? - ✔✔tyrosine
✔✔serotonin is synthesized from which of the following amino acids? - ✔✔tryptophan
✔✔which of the following is the regulatory enzyme in pyrimidine synthesis? -
✔✔carbamoyl phosphate synthetase II
✔✔methotrexate is a potent anticancer agent that starves dividing cells of
deoxyribonucleotides through direct inhibition of which of the following processes? -
✔✔metabolism of folic acid
