Question 1

Which of the following is NOT a characteristic of alkaptonuria?

Accepted Answer

A) excretion of homogentisate 
B) urine turning dark on standing due to air oxidation 
C) possibility of arthritis due to accumulation of homogentisate in joints 
D) possibility of mental retardation due to accumulation of Phe metabolites 
A) excretion of homogentisate 
B) urine turning dark on standing due to air oxidation 
C) possibility of arthritis due to accumulation of homogentisate in joints 
D) possibility of mental retardation due to accumulation of Phe metabolites D

Question 2

Which of the following amino acids is classified as an essential amino acid?

Accepted Answer

A) proline 
B) valine 
C) glutamine 
D) aspartate 
A) proline 
B) valine 
C) glutamine 
D) aspartate B

Question 3

Which of the following describes the role of N-acetylglutamate in the incorporation of ammonium into metabolic intermediates?

Accepted Answer

A) coenzyme for glutamine synthetase (GS) 
B) competitive inhibitor for glutamine synthetase (GS) 
C) allosteric activator for carbamoyl-phosphate synthetase I (CPS-I) 
D) substrate for the amination of the g-glutamyl-phosphate 
A) coenzyme for glutamine synthetase (GS) 
B) competitive inhibitor for glutamine synthetase (GS) 
C) allosteric activator for carbamoyl-phosphate synthetase I (CPS-I) 
D) substrate for the amination of the g-glutamyl-phosphate C

Question 4

Which of the following molecules is NOT a convergent metabolic intermediate of a-amino acid carbon skeletons?

Accepted Answer

A) citrate 
B) α-ketoglutarate 
C) oxaloacetate 
D) succinyl-CoA 
A) citrate 
B) α-ketoglutarate 
C) oxaloacetate 
D) succinyl-CoA

Question 5

Which of the following compounds is involved in electron transport carried out by nitrate reductase?

Accepted Answer

A) NADH 
B) FMN 
C) MoCo 
D) CO₂ 
A) NADH 
B) FMN 
C) MoCo 
D) CO₂

Question 6

Which of the following compounds provides the 6 electrons required by nitrite reductase to reduce NO₂⁻ to NH₄⁺ in higher plants?

Accepted Answer

A) plastoquinone 
B) heme 
C) CO₂ 
D) ferredoxin 
A) plastoquinone 
B) heme 
C) CO₂ 
D) ferredoxin

Question 7

Which of the following amino acids is formed by transamination of pyruvate with glutamate?

Accepted Answer

A) alanine 
B) serine 
C) cysteine 
D) aspartate 
A) alanine 
B) serine 
C) cysteine 
D) aspartate

Question 8

Which of the following describes how control over nitrogenase activity accomplished?

Accepted Answer

A) NH₄⁺ prevents expression of the genes that encode nitrogenase. 
B) ATP serves as an allosteric activator. 
C) AMP serves as an allosteric inhibitor. 
D) Phosphorylation prevents activity. 
A) NH₄⁺ prevents expression of the genes that encode nitrogenase. 
B) ATP serves as an allosteric activator. 
C) AMP serves as an allosteric inhibitor. 
D) Phosphorylation prevents activity.

Question 9

Which of the following is a commonly used transamination pair?

Accepted Answer

A) Asp / oxaloacetate 
B) Phe / phenylpyruvate 
C) Glu / pyruvate 
D) Ala / α-ketoglutarate 
A) Asp / oxaloacetate 
B) Phe / phenylpyruvate 
C) Glu / pyruvate 
D) Ala / α-ketoglutarate

Question 10

Which of the following explains why bacterial glutamine synthetase monomers are inactive?

Accepted Answer

A) They must be phosphorylated for activity. 
B) They must be activated by binding glutamine. 
C) They must be stacked for interface active site development. 
D) They must be combined for allosteric regulation. 
A) They must be phosphorylated for activity. 
B) They must be activated by binding glutamine. 
C) They must be stacked for interface active site development. 
D) They must be combined for allosteric regulation.

Question 11

Which of the following identifies where nitrifying bacteria obtain their chemical energy?

Accepted Answer

A) from the formation of NH₄⁺ from N₂ gas 
B) from the oxidation of NH₄⁺ to N₂ 
C) from the oxidation of NH₄⁺ to NO₃- 
D) from the formation of NO₂- from NO₃- 
A) from the formation of NH₄⁺ from N₂ gas 
B) from the oxidation of NH₄⁺ to N₂ 
C) from the oxidation of NH₄⁺ to NO₃- 
D) from the formation of NO₂- from NO₃-

Question 12

Which of the following enzymes catalyzes the reaction below?
Glutamate + NAD(P)⁺ + H₂O → NH₄⁺ + α-ketoglutarate + NAD(P)H + H⁺

Accepted Answer

A) nitrogenase 
B) carbamoyl-phosphate synthetase (CPS-I) 
C) glutamine synthetase (GS) 
D) glutamate dehydrogenase (GDH) 
A) nitrogenase 
B) carbamoyl-phosphate synthetase (CPS-I) 
C) glutamine synthetase (GS) 
D) glutamate dehydrogenase (GDH)

Question 13

Which of the following regarding the 3-phosphoglycerate family is correct?

Accepted Answer

A) Production of glycine also produces N5,N10-methylene-THF,which is important in the biosynthesis of purines. 
B) 3-PG is diverted from glycolysis by phosphoglycerate mutase. 
C) Serine,glycine,and methionine are all non-essential amino acids. 
D) Glycine production is regulated by a direct feedback mechanism. 
A) Production of glycine also produces N5,N10-methylene-THF,which is important in the biosynthesis of purines. 
B) 3-PG is diverted from glycolysis by phosphoglycerate mutase. 
C) Serine,glycine,and methionine are all non-essential amino acids. 
D) Glycine production is regulated by a direct feedback mechanism.

Question 14

How are glutamic acid,glutamine,proline,and arginine related to the process of amino acid biosynthesis?

Accepted Answer

A) They are all derived from a-ketoglutarate. 
B) They are all derivatives of acetyl-CoA. 
C) They are all derivatives of pyruvate. 
D) They are all derived from aspartate. 
A) They are all derived from a-ketoglutarate. 
B) They are all derivatives of acetyl-CoA. 
C) They are all derivatives of pyruvate. 
D) They are all derived from aspartate.

Question 15

Which of the following regarding the urea cycle is correct?

Accepted Answer

A) Stimulation of carbamoyl-phosphate synthetase I (CPS-I)decreases the activity of the urea cycle. 
B) It results in the accumulation of excess nitrogen. 
C) It is linked to the citric acid cycle through citrate. 
D) It is completed by the regeneration of ornithine from arginine. 
A) Stimulation of carbamoyl-phosphate synthetase I (CPS-I)decreases the activity of the urea cycle. 
B) It results in the accumulation of excess nitrogen. 
C) It is linked to the citric acid cycle through citrate. 
D) It is completed by the regeneration of ornithine from arginine.

Question 16

Which of the following classes of enzymes does glutamine synthetase belong to?

Accepted Answer

A) isomerase 
B) oxidoreductase 
C) ligase 
D) transferase 
A) isomerase 
B) oxidoreductase 
C) ligase 
D) transferase

Question 17

The structural difference between serine and homoserine is the same as the structural difference between cysteine and homocysteine.How are homoserine and homocysteine different from their commonly occurring amino acid partners?

Accepted Answer

A) 1 additional -CH₂- group 
B) 1 additional -COOH group 
C) 1 additional -NH₂ group 
D) 2 additional -NH₂ groups 
A) 1 additional -CH₂- group 
B) 1 additional -COOH group 
C) 1 additional -NH₂ group 
D) 2 additional -NH₂ groups

Question 18

Which of the following is a characteristic of maple syrup urine disease?

Accepted Answer

A) non-hereditary enzyme defect 
B) decreased levels of Val,Leu,and Ile and their corresponding a-keto acids in blood and urine 
C) elevated blood levels of acetoacetate and b-hydroxybutyrate 
D) fatal without detection and treatment 
A) non-hereditary enzyme defect 
B) decreased levels of Val,Leu,and Ile and their corresponding a-keto acids in blood and urine 
C) elevated blood levels of acetoacetate and b-hydroxybutyrate 
D) fatal without detection and treatment

Question 19

Which of the following describes the process of nitrogen fixation?

Accepted Answer

A) the reduction of NO₃- to NH₄⁺ 
B) the formation of NH₄⁺ from N₂ gas 
C) the oxidation of NH₄⁺ to N₂ gas 
D) the oxidation of NH₄⁺ to NO₃- 
A) the reduction of NO₃- to NH₄⁺ 
B) the formation of NH₄⁺ from N₂ gas 
C) the oxidation of NH₄⁺ to N₂ gas 
D) the oxidation of NH₄⁺ to NO₃-

Question 20

Which of the following acts in feedback inhibition of glutamine synthetase in prokaryotes?

Accepted Answer

A) proline 
B) ATP 
C) glucose-6-phosphate 
D) histidine 
A) proline 
B) ATP 
C) glucose-6-phosphate 
D) histidine

Exam 23: Nitrogen Acquisition and Amino Acid Metabolism

Which of the following is NOT a characteristic of alkaptonuria?

Which of the following amino acids is classified as an essential amino acid?

Which of the following describes the role of N-acetylglutamate in the incorporation of ammonium into metabolic intermediates?

Which of the following molecules is NOT a convergent metabolic intermediate of a-amino acid carbon skeletons?

Which of the following compounds is involved in electron transport carried out by nitrate reductase?

Which of the following compounds provides the 6 electrons required by nitrite reductase to reduce NO₂⁻ to NH₄⁺ in higher plants?

Which of the following amino acids is formed by transamination of pyruvate with glutamate?

Which of the following describes how control over nitrogenase activity accomplished?

Which of the following is a commonly used transamination pair?

Which of the following explains why bacterial glutamine synthetase monomers are inactive?

Which of the following identifies where nitrifying bacteria obtain their chemical energy?

Which of the following enzymes catalyzes the reaction below? Glutamate + NAD(P)⁺ + H₂O → NH₄⁺ + α-ketoglutarate + NAD(P)H + H⁺

Which of the following regarding the 3-phosphoglycerate family is correct?

How are glutamic acid,glutamine,proline,and arginine related to the process of amino acid biosynthesis?

Which of the following regarding the urea cycle is correct?

Which of the following classes of enzymes does glutamine synthetase belong to?

The structural difference between serine and homoserine is the same as the structural difference between cysteine and homocysteine.How are homoserine and homocysteine different from their commonly occurring amino acid partners?

Which of the following is a characteristic of maple syrup urine disease?

Which of the following describes the process of nitrogen fixation?

Which of the following acts in feedback inhibition of glutamine synthetase in prokaryotes?

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Lipid Biosynthesis

Membranes and Membrane Transport

The Reception and Transmission of Extracellular Information

Enzymes Kinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Nutrition and the Organization of Metabolism

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Synthesis and Degradation of Nucleotides

Recombinant Dna: Cloning and Creation of Chimeric Genes

DNA Metabolism: Replication, recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Post-Transcriptional Regulation of Gene Expression

Completing the Protein Life Cycle: Folding, processing, and Degradation

Metabolic Integration and Organ Specialization

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