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Toxicology 2 Questions and Answers
Xenobiotic biotransformation is performed by multiple enzymes in
multiple subcellular locations. Where would one of these enzymes
most likely NOT be located?
-cytosol
-golgi apparatus
-lysosome
-mitochondria
-microsome
Ans: golgi apparatus
All of the following statements regarding hydrolysis, reduction,
and oxidation biotransformations are true EXCEPT:
-the xenobiotic can be hydrolyzed
-the xenobiotic can be reduced
-there is a large increase in hydrophilicity
-the reactions introduce a functional group to the molecule
-the xenobiotic can be oxidized
Ans: there is a large increase in hydrophilicity
Which of the following is often conjugated to xenobiotics during
phase II biotransformations?
-alcohol group
-sulfhydryl group
-sulfate group
-aldehyde group
-carbonyl group
Ans: sulfate group
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Which of the following is a true statement about the
biotransformation of ethanol?
-alcohol dehydrogenase is only present in the liver
-ethanol is reduced to acetaldehyde by alcohol dehydrogenase
-ethanol and hydrogen peroxide combine to form acetaldehyde
with the aid of catalase
-in spite of its catalytic versatility, cytochrome p450 does not aid
in ehtanol oxidation
-acetaldehyde is oxidized to acetic acid in the mitochondria by
aldehyde dehydrogenase
Ans: acetaldehyde is oxidized to acetic acid in the mitochondria by
aldehyde dehydrogenase
Which of the following enzymes is responsible for the
biotransformation and elimination of serotonin?
-cytochrome p450
-monoamine oxidase
-flavin monooxygenase
-xanthine oxidase
-paraoxonase
Ans: monoamine oxidase
Which of the following reactions would likely NOT be catalyzed by
cytochrome p450?
-dehydrogenation
-oxidative group transfer
-epoxidation
-reductive dehalogenation
-ester cleavage
Ans: reductive dehalogenation
All of the following statements regarding cytochrome p450 are
true EXCEPT:
© 2025 All rights reserved
Toxicology 2 Questions and Answers
Xenobiotic biotransformation is performed by multiple enzymes in
multiple subcellular locations. Where would one of these enzymes
most likely NOT be located?
-cytosol
-golgi apparatus
-lysosome
-mitochondria
-microsome
Ans: golgi apparatus
All of the following statements regarding hydrolysis, reduction,
and oxidation biotransformations are true EXCEPT:
-the xenobiotic can be hydrolyzed
-the xenobiotic can be reduced
-there is a large increase in hydrophilicity
-the reactions introduce a functional group to the molecule
-the xenobiotic can be oxidized
Ans: there is a large increase in hydrophilicity
Which of the following is often conjugated to xenobiotics during
phase II biotransformations?
-alcohol group
-sulfhydryl group
-sulfate group
-aldehyde group
-carbonyl group
Ans: sulfate group
© 2025 All rights reserved
, 2 | Page
Which of the following is a true statement about the
biotransformation of ethanol?
-alcohol dehydrogenase is only present in the liver
-ethanol is reduced to acetaldehyde by alcohol dehydrogenase
-ethanol and hydrogen peroxide combine to form acetaldehyde
with the aid of catalase
-in spite of its catalytic versatility, cytochrome p450 does not aid
in ehtanol oxidation
-acetaldehyde is oxidized to acetic acid in the mitochondria by
aldehyde dehydrogenase
Ans: acetaldehyde is oxidized to acetic acid in the mitochondria by
aldehyde dehydrogenase
Which of the following enzymes is responsible for the
biotransformation and elimination of serotonin?
-cytochrome p450
-monoamine oxidase
-flavin monooxygenase
-xanthine oxidase
-paraoxonase
Ans: monoamine oxidase
Which of the following reactions would likely NOT be catalyzed by
cytochrome p450?
-dehydrogenation
-oxidative group transfer
-epoxidation
-reductive dehalogenation
-ester cleavage
Ans: reductive dehalogenation
All of the following statements regarding cytochrome p450 are
true EXCEPT:
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