Question 1

Which of the following is NOT a characteristic feature of ATP:GS:adenylyl transferase (AT)?

Accepted Answer

A) It catalyzes the adenylation of glutamine synthetase. 
B) It exists in 2 forms,PIIA and PIID.PIIA causes the deadenylation of glutamine synthetase,and its activity increases with an increase in glutamine. 
C) AT:PIIA needs ATP to complete the reaction. 
D) It is an enzyme that causes the adenylation/deadenylation of a specific tyrosine residue. 
A) It catalyzes the adenylation of glutamine synthetase. 
B) It exists in 2 forms,PIIA and PIID.PIIA causes the deadenylation of glutamine synthetase,and its activity increases with an increase in glutamine. 
C) AT:PIIA needs ATP to complete the reaction. 
D) It is an enzyme that causes the adenylation/deadenylation of a specific tyrosine residue.

Question 2

Which of the following describes the role ATP plays in the nitrogenase complex?

Accepted Answer

A) breaks the N₂ triple bond 
B) provides electrons 
C) phosphorylates the enzyme 
D) transfers electrons from ferredoxin 
A) breaks the N₂ triple bond 
B) provides electrons 
C) phosphorylates the enzyme 
D) transfers electrons from ferredoxin

Question 3

Which of the following amino acid carbon skeletons converges to pyruvate?

Accepted Answer

A) methionine 
B) isoleucine 
C) glutamate 
D) cysteine 
A) methionine 
B) isoleucine 
C) glutamate 
D) cysteine

Question 4

The reaction,2 NH₄⁺ + α-ketoglutarate + NADPH + ATP →glutamine + NADP⁺ + ADP + Pᵢ + H₂O,is the combined result of which of the following two enzymes?

Accepted Answer

A) glutamate dehydrogenase and glutamine synthetase 
B) nitrogenase and glutamate dehydrogenase 
C) glutamine synthetase and nitrogenase 
D) α-ketoglutarate dehydrogenase and glutamate synthetase 
A) glutamate dehydrogenase and glutamine synthetase 
B) nitrogenase and glutamate dehydrogenase 
C) glutamine synthetase and nitrogenase 
D) α-ketoglutarate dehydrogenase and glutamate synthetase

Question 5

Which of the following molecules is synthesized using chorismate as a precursor?

Accepted Answer

A) threonine 
B) homocysteine 
C) tyrosine 
D) alanine 
A) threonine 
B) homocysteine 
C) tyrosine 
D) alanine

Question 6

Which of the following compounds is reduced to ammonia during the second step of nitrate assimilation?

Accepted Answer

A) nitrogen 
B) carbon 
C) nitrite 
D) carbon dioxide 
A) nitrogen 
B) carbon 
C) nitrite 
D) carbon dioxide

Question 7

Which of the following serves directly as one of the nitrogen atoms of a urea molecule?

Accepted Answer

A) the amide N of Asn 
B) the N of Asp 
C) the R-group N of Lys 
D) the N of glucosamine 
A) the amide N of Asn 
B) the N of Asp 
C) the R-group N of Lys 
D) the N of glucosamine

Question 8

Which of the following reactions are denitrifying bacteria NOT capable of?

Accepted Answer

A) reducing NO₃- to N₂ 
B) using NO₃- as an electron acceptor in their energy-producing pathways 
C) oxidizing NH₄⁺ to NO₃- 
D) reducing the combined-nitrogen levels 
A) reducing NO₃- to N₂ 
B) using NO₃- as an electron acceptor in their energy-producing pathways 
C) oxidizing NH₄⁺ to NO₃- 
D) reducing the combined-nitrogen levels

Question 9

Which of the following explains why animals totally dependent on plants and microorganisms for nitrogen fixation and nitrate assimilation?

Accepted Answer

A) They lack the enzyme aminotransferase. 
B) They lack the enzymes to reduce N₂ and NO₃- to NH₄⁺. 
C) They lack carbamoyl-phosphate synthetase I. 
D) They lack glutamate dehydrogenase. 
A) They lack the enzyme aminotransferase. 
B) They lack the enzymes to reduce N₂ and NO₃- to NH₄⁺. 
C) They lack carbamoyl-phosphate synthetase I. 
D) They lack glutamate dehydrogenase.

Question 10

Which of the following amino acids are referred to as the ketogenic amino acids?

Accepted Answer

A) those that are precursors for glucose synthesis 
B) those degraded to yield acetyl-CoA or acetoacetate 
C) those that cannot be converted to fatty acids or ketone bodies 
D) those degraded to yield succinyl-CoA,pyruvate,a-ketoglutarate,fumarate,and oxaloacetate 
A) those that are precursors for glucose synthesis 
B) those degraded to yield acetyl-CoA or acetoacetate 
C) those that cannot be converted to fatty acids or ketone bodies 
D) those degraded to yield succinyl-CoA,pyruvate,a-ketoglutarate,fumarate,and oxaloacetate

Question 11

Which of the following regarding the process of transamination is correct?

Accepted Answer

A) The coenzyme needed is thiamine pyrophosphate (TPP). 
B) It is characterized by the transfer of an α-carboxyl group from an amino acid to the α-keto position of an α-keto acid. 
C) The amino donor becomes an α-keto acid. 
D) Humans are capable of synthesizing the α-keto acid analog of essential amino acids and using transamination to form the amino acids,but are not able to construct carbon skeletons of the non-essential amino acids. 
A) The coenzyme needed is thiamine pyrophosphate (TPP). 
B) It is characterized by the transfer of an α-carboxyl group from an amino acid to the α-keto position of an α-keto acid. 
C) The amino donor becomes an α-keto acid. 
D) Humans are capable of synthesizing the α-keto acid analog of essential amino acids and using transamination to form the amino acids,but are not able to construct carbon skeletons of the non-essential amino acids.

Question 12

Ornithine serves 3 metabolically important roles,but is not found in proteins.Which of the following is one of the important roles of ornithine?

Accepted Answer

A) precursor in the synthesis of aspartate 
B) an intermediate in the urea cycle 
C) formation of ornithine from serine 
D) condenses with aspartate to form argininosuccinate 
A) precursor in the synthesis of aspartate 
B) an intermediate in the urea cycle 
C) formation of ornithine from serine 
D) condenses with aspartate to form argininosuccinate

Question 13

Which of the following describes how homoserine and homocysteine are related to serine and cysteine,respectively?

Accepted Answer

A) They have an extra amino group. 
B) They have an additional methylene group. 
C) They have an additional carboxyl group. 
D) They have an aldehyde group. 
A) They have an extra amino group. 
B) They have an additional methylene group. 
C) They have an additional carboxyl group. 
D) They have an aldehyde group.

Question 14

Which of the following is related to elevated level of homocysteine in the blood?

Accepted Answer

A) excess folic acid 
B) homocystinuria at very low levels 
C) lower risk of heart attack and stroke 
D) folic acid-dependent conversion of homocysteine to methionine 
A) excess folic acid 
B) homocystinuria at very low levels 
C) lower risk of heart attack and stroke 
D) folic acid-dependent conversion of homocysteine to methionine

Question 15

Which of the following molecules is transaminated to form aspartate?

Accepted Answer

A) asparagine 
B) aspartame 
C) oxaloacetate 
D) α-ketoglutarate 
A) asparagine 
B) aspartame 
C) oxaloacetate 
D) α-ketoglutarate

Question 16

Which of the following amino acid's carbon and nitrogen atoms are all used in the biosynthesis of ornithine?

Accepted Answer

A) proline 
B) valine 
C) alanine 
D) glutamate 
A) proline 
B) valine 
C) alanine 
D) glutamate

Question 17

Which of the following is a requirement of all N₂-fixing systems?

Accepted Answer

A) the enzyme nitrogenase 
B) GTP 
C) H₂Ofree conditions 
D) a strong oxidizer such as ferredoxin 
A) the enzyme nitrogenase 
B) GTP 
C) H₂Ofree conditions 
D) a strong oxidizer such as ferredoxin

Question 18

Herbicides (e.g.,"Roundup")inhibit biosynthesis of "essential" amino acids.Which of the following explains why these herbicides,however,relatively safe for animal exposure?

Accepted Answer

A) They lack the enzymes for photosynthesis. 
B) They lack the enzymes for the glyoxylate cycle. 
C) They lack the enzymes for the glutamine synthesis pathway . 
D) They lack the enzymes for the Phe,Val,Leu,Ile,and His biosynthetic pathways. 
A) They lack the enzymes for photosynthesis. 
B) They lack the enzymes for the glyoxylate cycle. 
C) They lack the enzymes for the glutamine synthesis pathway . 
D) They lack the enzymes for the Phe,Val,Leu,Ile,and His biosynthetic pathways.

Question 19

Which of the following is a characteristic of phenylketonuria?

Accepted Answer

A) urine turning dark on standing due to air oxidation 
B) deficiency or defect in phenylalanine hydroxylase 
C) treated by putting patient on a diet high in phenylalanine 
D) treated patients suffering severe mental retardation 
A) urine turning dark on standing due to air oxidation 
B) deficiency or defect in phenylalanine hydroxylase 
C) treated by putting patient on a diet high in phenylalanine 
D) treated patients suffering severe mental retardation

Question 20

Which of the following amino acids is biosynthesized from aspartate?

Accepted Answer

A) serine 
B) glycine 
C) cysteine 
D) lysine 
A) serine 
B) glycine 
C) cysteine 
D) lysine

Exam 23: Nitrogen Acquisition and Amino Acid Metabolism

Which of the following is NOT a characteristic feature of ATP:GS:adenylyl transferase (AT)?

Which of the following describes the role ATP plays in the nitrogenase complex?

Which of the following amino acid carbon skeletons converges to pyruvate?

The reaction,2 NH₄⁺ + α-ketoglutarate + NADPH + ATP →glutamine + NADP⁺ + ADP + Pᵢ + H₂O,is the combined result of which of the following two enzymes?

Which of the following molecules is synthesized using chorismate as a precursor?

Which of the following compounds is reduced to ammonia during the second step of nitrate assimilation?

Which of the following serves directly as one of the nitrogen atoms of a urea molecule?

Which of the following reactions are denitrifying bacteria NOT capable of?

Which of the following explains why animals totally dependent on plants and microorganisms for nitrogen fixation and nitrate assimilation?

Which of the following amino acids are referred to as the ketogenic amino acids?

Which of the following regarding the process of transamination is correct?

Ornithine serves 3 metabolically important roles,but is not found in proteins.Which of the following is one of the important roles of ornithine?

Which of the following describes how homoserine and homocysteine are related to serine and cysteine,respectively?

Which of the following is related to elevated level of homocysteine in the blood?

Which of the following molecules is transaminated to form aspartate?

Which of the following amino acid's carbon and nitrogen atoms are all used in the biosynthesis of ornithine?

Which of the following is a requirement of all N₂-fixing systems?

Herbicides (e.g.,"Roundup")inhibit biosynthesis of "essential" amino acids.Which of the following explains why these herbicides,however,relatively safe for animal exposure?

Which of the following is a characteristic of phenylketonuria?

Which of the following amino acids is biosynthesized from aspartate?

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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