Question 1

Deoxyribonucleotides are formed

Accepted Answer

A)  by a pathway entirely different from that of ribonucleotides 
B)  exclusively by hydrolysis of the DNA of the organism 
C)  as monophosphates by reduction of ribonucleoside monophosphates 
D)  as diphosphates by reduction of ribonucleoside disphosphates 
A)  by a pathway entirely different from that of ribonucleotides 
B)  exclusively by hydrolysis of the DNA of the organism 
C)  as monophosphates by reduction of ribonucleoside monophosphates 
D)  as diphosphates by reduction of ribonucleoside disphosphates

Question 2

The following two amino acids are key to the transfers of amino groups during breakdown and synthesis of amino acids.

Accepted Answer

A)  GLU and ASP 
B)  GLU and ARG 
C)  GLU and GLN 
D)  ALA and GLN 
E)  ASP and GLN 
A)  GLU and ASP 
B)  GLU and ARG 
C)  GLU and GLN 
D)  ALA and GLN 
E)  ASP and GLN

Question 3

Glycine, alanine, serine, histidine, tryptophan, CTP, AMP, and carbamoyl-phosphate all have what in common?

Accepted Answer

A)  They are all inhibitors of glutamine synthase 
B)  They are all amino acids 
C)  They are all cofactors in transamination reactions 
D)  They are activators of the urea cycle 
A)  They are all inhibitors of glutamine synthase 
B)  They are all amino acids 
C)  They are all cofactors in transamination reactions 
D)  They are activators of the urea cycle

Question 4

While the reduction of nitrogen to ammonia in plants follows the same net chemical reaction, the source of electrons for the process varies from plant to plant.

Accepted Answer

A) True 
 B)False

Question 5

Nitrogen fixation in legumes may use as much as half of the ATP made in the plant.

Accepted Answer

A) True 
 B)False

Question 6

In the urea cycle, the molecule that is synthesized in the cytosol and transported to the mitochondrial matrix for subsequent reaction is

Accepted Answer

A)  citrulline 
B)  ornithine 
C)  argininosuccinate 
D)  aspartate 
E)  fumarate 
A)  citrulline 
B)  ornithine 
C)  argininosuccinate 
D)  aspartate 
E)  fumarate

Question 7

The conversion of glutamate to glutamine is catalyzed by glutamine synthetase and requires ATP.

Accepted Answer

A) True 
 B)False

Question 8

Which of the following compounds does not serve as an intermediate for the entry of amino acid carbon chains into the major metabolic pathways?

Accepted Answer

A)  Alpha-ketoglutarate. 
B)  Pyruvate. 
C)  Glyceraldehyde. 
D)  Acetyl CoA. 
E)  All of these are entry points for amino acid catabolism. 
A)  Alpha-ketoglutarate. 
B)  Pyruvate. 
C)  Glyceraldehyde. 
D)  Acetyl CoA. 
E)  All of these are entry points for amino acid catabolism.

Question 9

Pyridoxal phosphate forms a Schiff base with amino groups in transaminase reactions.

Accepted Answer

A) True 
 B)False

Question 10

Which group of small molecules best fit the boxes associated with the reaction shown?  
$$\begin{array} { l l l } 
& \mathbf { A } & \mathbf { B } \
\hline \text { I. } & 2 \mathrm { ATP } & 2 \mathrm { ADP } + \mathrm { P } _ { i } \
\text { II. } & \text { ATP } & \mathrm { AMP } + \mathrm { P } _ { i } \
\text { III. } & \text { ATP } & \mathrm { ADP } ^ { 2 } \
\text { IV. } & \text { NADPH } & \mathrm { NADP } ^ { + }
\end{array}$$

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
A)  I 
B)  II 
C)  III 
D)  IV

Question 11

The form in which nitrogen waste is removed from the body is dependent mostly on the organism's availability of water.

Accepted Answer

A) True 
 B)False

Question 12

The nitrogen-fixing enzyme system, nitrogenase, is found exclusively in

Accepted Answer

A)  plants 
B)  bacteria 
C)  some viruses 
D)  eukaryotic organisms 
E)  mammals 
A)  plants 
B)  bacteria 
C)  some viruses 
D)  eukaryotic organisms 
E)  mammals

Question 13

The two nitrogens in urea arise directly from:

Accepted Answer

A)  Ammonia and aspartic acid. 
B)  Carbamoyl phosphate and aspartic acid. 
C)  Carbamoyl phosphate and glutamic acid. 
D)  Ammonia and glutamic acid. 
E)  Carbamoyl phosphate and glutamine. 
A)  Ammonia and aspartic acid. 
B)  Carbamoyl phosphate and aspartic acid. 
C)  Carbamoyl phosphate and glutamic acid. 
D)  Ammonia and glutamic acid. 
E)  Carbamoyl phosphate and glutamine.

Question 14

A metabolic intermediate that is not a precursor for an amino acid family is

Accepted Answer

A)  α-ketoglutarate 
B)  pyruvate 
C)  glyceraldehyde-3-phosphate 
D)  oxaloacetate 
A)  α-ketoglutarate 
B)  pyruvate 
C)  glyceraldehyde-3-phosphate 
D)  oxaloacetate

Question 15

The ultimate end products of xanthine catabolsim are:

Accepted Answer

A)  two pyrimidines 
B)  urea and glyoxylate 
C)  uric acid 
D)  allantoin 
A)  two pyrimidines 
B)  urea and glyoxylate 
C)  uric acid 
D)  allantoin

Question 16

If an amino acid's degradation pathway leads to α-ketoglutarate, is it glucogenic?

Accepted Answer

A)  Yes. 
B)  No. 
C)  Only if the organism has a glyoxylate pathway. 
D)  Only if the organism does not have a glyoxylate pathway. 
A)  Yes. 
B)  No. 
C)  Only if the organism has a glyoxylate pathway. 
D)  Only if the organism does not have a glyoxylate pathway.

Question 17

Purine salvage reactions

Accepted Answer

A)  use bases as the substrate 
B)  use nucleosides as the substrate 
C)  produce nucleosides as products 
D)  require the hydrolysis of ATP 
E)  none of these 
A)  use bases as the substrate 
B)  use nucleosides as the substrate 
C)  produce nucleosides as products 
D)  require the hydrolysis of ATP 
E)  none of these

Question 18

Kwashiorkor is a malnutrition disease in which high quality proteins are lacking, even if enough calories are available for survival.

Accepted Answer

A) True 
 B)False

Question 19

Which of the following is not an intermediate in the urea cycle?

Accepted Answer

A)  arginine 
B)  citrulline 
C)  ornithine 
D)  lysine 
A)  arginine 
B)  citrulline 
C)  ornithine 
D)  lysine

Question 20

The initial, common intermediate in purine catabolism for both AMP and GMP is

Accepted Answer

A)  xanthine 
B)  hypoxanthine 
C)  inosine 
D)  uric acid 
A)  xanthine 
B)  hypoxanthine 
C)  inosine 
D)  uric acid

Exam 23: The Metabolism of Nitrogen

Deoxyribonucleotides are formed

The following two amino acids are key to the transfers of amino groups during breakdown and synthesis of amino acids.

Glycine, alanine, serine, histidine, tryptophan, CTP, AMP, and carbamoyl-phosphate all have what in common?

While the reduction of nitrogen to ammonia in plants follows the same net chemical reaction, the source of electrons for the process varies from plant to plant.

Nitrogen fixation in legumes may use as much as half of the ATP made in the plant.

In the urea cycle, the molecule that is synthesized in the cytosol and transported to the mitochondrial matrix for subsequent reaction is

The conversion of glutamate to glutamine is catalyzed by glutamine synthetase and requires ATP.

Which of the following compounds does not serve as an intermediate for the entry of amino acid carbon chains into the major metabolic pathways?

Pyridoxal phosphate forms a Schiff base with amino groups in transaminase reactions.

Which group of small molecules best fit the boxes associated with the reaction shown? I. 2 2+ II. ATP + III. ATP IV. NADPH

The form in which nitrogen waste is removed from the body is dependent mostly on the organism's availability of water.

The nitrogen-fixing enzyme system, nitrogenase, is found exclusively in

The two nitrogens in urea arise directly from:

A metabolic intermediate that is not a precursor for an amino acid family is

The ultimate end products of xanthine catabolsim are:

If an amino acid's degradation pathway leads to α-ketoglutarate, is it glucogenic?

Purine salvage reactions

Kwashiorkor is a malnutrition disease in which high quality proteins are lacking, even if enough calories are available for survival.

Which of the following is not an intermediate in the urea cycle?

The initial, common intermediate in purine catabolism for both AMP and GMP is

Biochemistry and the Organization of Cells

Water: the Solvent for Biochemical Reactions

Amino Acids and Peptides

The Three-Dimensional Structure of Proteins

Protein Purification and Characterization Techniques

The Behavior of Proteins: Enzymes

The Behavior of Proteins: Enzymes, Mechanisms, and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids: How Structure Conveys Information

Biosynthesis of Nucleic Acids: Replication

Transcription of the Genetic Code: Biosynthesis of RNA

Protein Synthesis: Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses, Cancer, and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

Integration of Metabolism: Cellular Signaling

Filters