BIOC 385 Exam 3 (Summer 2025)
questions well answered
In the duodenum, enter peptidase __________.
A.
B.
C.
D. - correct answer ✔✔cleaves trypsinogen to make trypsin.
Which of the three proteins in the ubiquination pathway is the most responsible for recognizing
the ubiquintated target protein?
A. E3
B. E2
C. All of the target proteins
D. E1 - correct answer ✔✔A. E3
What is the regulatory mechanism by which arginine stimulates flux through the urea cycle?
,A. Arginine stimulates flux through the urea cycle by inhibiting the enzyme nitrogenase.
B. Arginine stimulates the production of N-acetylglutamate which activates arginase.
C. Arginine stimulates the production of the allosteric activator N-acetylglutamate.
D. Arginine stimulates the activity of carbamoyl phosphate synthetase I. - correct answer ✔✔C.
Arginine stimulates the production of the allosteric activator N-acetylglutamate.
A person who has alkaptonuria is easily diagnosed from their black urine. What causes the black
color?
A. Oxidation of phenylalanine
B. Oxidation of homogentisate
C. Reduction of acetoacyl-CoA
D. phenylpyruvate and phenylacetate. - correct answer ✔✔B. Oxidation of homogentisate
Aspartate is a(n) ________ amino acid, so if a person had a diet that contained no aspartate
then ________.
A. nonessential; they would be unable to synthesize proteins.
B. essential; they would be unable to synthesize proteins.
,C. essential; aspartate could be synthesized from other intermediates.
D. nonessential; aspartate could be synthesized from other intermediates. - correct answer
✔✔D. nonessential; aspartate could be synthesized from other intermediates.
What is the mechanism by which glyphosate, the active ingredient in Roundup, kills plants?
A. Glyphosate is an allosteric activator to plant EPSP synthase.
B. Glyphosate binds to tyrosine and prevents incorporation into proteins
C. Glyphosate inhibits the production of aspartate, alanine, and glycine.
D. Glyphosate is a competitive inhibitor of plant EPSP synthase. - correct answer ✔✔D.
Glyphosate is a competitive inhibitor of plant EPSP synthase.
Diseases affecting heme biosynthesis as a result of deficiencies in the heme biosynthetic
pathway are called _________.
A. porphyria
B. phenylketonuria
C. albinism
D. alkaptonuria - correct answer ✔✔A. porphyria
, What molecule signals the endothelial cell to produce nitric oxide, and what is the enzymatic
reaction?
A. dopamine;
L-arginine + 1.5 NADPH + H+ + 2O2 --> dopamine + NO + 1.5 NADP+
B. acetylcholine;
citrulline + NO + 1.5 NADP+ --> L-arginine + 1.5 NADPH + H+ + 2O2
C. acetylcholine;
L-arginine + 1.5 NADP+ + H+ + 2O2 --> citrulline + NO + 1.5 NADPH
D. citrulline;
L-arginine + 1.5NADP+ + H+ + 2O2 --> citrulline + NO + 1.5NADP+ - correct answer ✔✔C.
acetylcholine;
L-arginine + 1.5 NADP+ + H+ + 2O2 --> citrulline + NO + 1.5 NADPH
Which of the following is the reaction for nitric oxide synthase?
A. L-arginine + 1.5 NADPH + H+ + 2O2 citrulline + NO + 1.5 NADP+
questions well answered
In the duodenum, enter peptidase __________.
A.
B.
C.
D. - correct answer ✔✔cleaves trypsinogen to make trypsin.
Which of the three proteins in the ubiquination pathway is the most responsible for recognizing
the ubiquintated target protein?
A. E3
B. E2
C. All of the target proteins
D. E1 - correct answer ✔✔A. E3
What is the regulatory mechanism by which arginine stimulates flux through the urea cycle?
,A. Arginine stimulates flux through the urea cycle by inhibiting the enzyme nitrogenase.
B. Arginine stimulates the production of N-acetylglutamate which activates arginase.
C. Arginine stimulates the production of the allosteric activator N-acetylglutamate.
D. Arginine stimulates the activity of carbamoyl phosphate synthetase I. - correct answer ✔✔C.
Arginine stimulates the production of the allosteric activator N-acetylglutamate.
A person who has alkaptonuria is easily diagnosed from their black urine. What causes the black
color?
A. Oxidation of phenylalanine
B. Oxidation of homogentisate
C. Reduction of acetoacyl-CoA
D. phenylpyruvate and phenylacetate. - correct answer ✔✔B. Oxidation of homogentisate
Aspartate is a(n) ________ amino acid, so if a person had a diet that contained no aspartate
then ________.
A. nonessential; they would be unable to synthesize proteins.
B. essential; they would be unable to synthesize proteins.
,C. essential; aspartate could be synthesized from other intermediates.
D. nonessential; aspartate could be synthesized from other intermediates. - correct answer
✔✔D. nonessential; aspartate could be synthesized from other intermediates.
What is the mechanism by which glyphosate, the active ingredient in Roundup, kills plants?
A. Glyphosate is an allosteric activator to plant EPSP synthase.
B. Glyphosate binds to tyrosine and prevents incorporation into proteins
C. Glyphosate inhibits the production of aspartate, alanine, and glycine.
D. Glyphosate is a competitive inhibitor of plant EPSP synthase. - correct answer ✔✔D.
Glyphosate is a competitive inhibitor of plant EPSP synthase.
Diseases affecting heme biosynthesis as a result of deficiencies in the heme biosynthetic
pathway are called _________.
A. porphyria
B. phenylketonuria
C. albinism
D. alkaptonuria - correct answer ✔✔A. porphyria
, What molecule signals the endothelial cell to produce nitric oxide, and what is the enzymatic
reaction?
A. dopamine;
L-arginine + 1.5 NADPH + H+ + 2O2 --> dopamine + NO + 1.5 NADP+
B. acetylcholine;
citrulline + NO + 1.5 NADP+ --> L-arginine + 1.5 NADPH + H+ + 2O2
C. acetylcholine;
L-arginine + 1.5 NADP+ + H+ + 2O2 --> citrulline + NO + 1.5 NADPH
D. citrulline;
L-arginine + 1.5NADP+ + H+ + 2O2 --> citrulline + NO + 1.5NADP+ - correct answer ✔✔C.
acetylcholine;
L-arginine + 1.5 NADP+ + H+ + 2O2 --> citrulline + NO + 1.5 NADPH
Which of the following is the reaction for nitric oxide synthase?
A. L-arginine + 1.5 NADPH + H+ + 2O2 citrulline + NO + 1.5 NADP+
