Question 1

Denitrification is carried out by

Accepted Answer

A)  animals. 
B)  green plants. 
C)  soil bacteria. 
D)  all of the above. 
E)  none of these 
A)  animals. 
B)  green plants. 
C)  soil bacteria. 
D)  all of the above. 
E)  none of these

Question 2

How many ATP equivalents are required to produce one molecule of urea from ammonia and aspartate?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  6 
A)  1 
B)  2 
C)  3 
D)  4 
E)  6

Question 3

Carbamoyl phosphate is made in both the mitochondria and the cytosol, because it is used in the synthesis of several different molecules which are made in either of the compartments.

Accepted Answer

A) True 
 B)False

Question 4

Cancer treatments which disrupt the function of folic acid have significant side effects, since this therapy also affects the growth of such rapidly dividing tissues as all of the following, except:

Accepted Answer

A)  Skin cells. 
B)  Red and white blood cells. 
C)  Nerve tissue. 
D)  Sperm. 
E)  All of these cell types are affected by this therapy. 
A)  Skin cells. 
B)  Red and white blood cells. 
C)  Nerve tissue. 
D)  Sperm. 
E)  All of these cell types are affected by this therapy.

Question 5

How many electrons are required for the reduction of one nitrogen molecule (N2) to two molecules of ammonia (NH3) and molecule of hydrogen (H2)?

Accepted Answer

A)  2 electrons. 
B)  4 electrons. 
C)  6 electrons. 
D)  8 electrons. 
E)  12 electrons. 
A)  2 electrons. 
B)  4 electrons. 
C)  6 electrons. 
D)  8 electrons. 
E)  12 electrons.

Question 6

In nitrogen fixation, the chemical change is

Accepted Answer

A)  NH4+ to NO2− 
B)  NO3− to NH4+ 
C)  N2 to NH4+ or NH3 
D)  NO2− to N2 
E)  none of these 
A)  NH4+ to NO2− 
B)  NO3− to NH4+ 
C)  N2 to NH4+ or NH3 
D)  NO2− to N2 
E)  none of these

Question 7

Many antibiotics, especially for viruses and cancer therapy involve inhibition of folic acid reactions, especially because folic acid is essential for this reaction:

Accepted Answer

A)  Synthesis of many amino acids. 
B)  Conversion of uracil to thymine for DNA synthesis. 
C)  Synthesis of deoxyribose for DNA synthesis. 
D)  None of these reactions explains the reason why inhibitors of folic acid act as antibiotics. 
E)  All of these reactions are reasons why inhibitors of folic acid act as antibiotics. 
A)  Synthesis of many amino acids. 
B)  Conversion of uracil to thymine for DNA synthesis. 
C)  Synthesis of deoxyribose for DNA synthesis. 
D)  None of these reactions explains the reason why inhibitors of folic acid act as antibiotics. 
E)  All of these reactions are reasons why inhibitors of folic acid act as antibiotics.

Question 8

In the synthesis of pyrimidine nucleotides, the ring system formed just before the attachment of PRPP is

Accepted Answer

A)  5-aminoimidazole 
B)  inosine 
C)  orotate 
D)  xanthine 
A)  5-aminoimidazole 
B)  inosine 
C)  orotate 
D)  xanthine

Question 9

Fluorouracil is an effective inhibitor of

Accepted Answer

A)  ribonucleotide reductase 
B)  thymidylate synthase 
C)  xanthine oxidase 
D)  carbamoyl phosphate synthetase 
A)  ribonucleotide reductase 
B)  thymidylate synthase 
C)  xanthine oxidase 
D)  carbamoyl phosphate synthetase

Question 10

If an amino acid is ketogenic, then it:

Accepted Answer

A)  has a catabolic pathway that leads to acetyl-CoA or acetoacetyl-CoA 
B)  has a one step pathway to a fatty acid 
C)  enters the citric acid cycle as pyruvate 
D)  enters the citric acid cycle as fumarate 
E)  none of these 
A)  has a catabolic pathway that leads to acetyl-CoA or acetoacetyl-CoA 
B)  has a one step pathway to a fatty acid 
C)  enters the citric acid cycle as pyruvate 
D)  enters the citric acid cycle as fumarate 
E)  none of these

Question 11

The serine family of amino acids includes synthesis of all the following amino acids, except:

Accepted Answer

A)  Serine. 
B)  Glycine. 
C)  Cysteine. 
D)  Methionine. 
E)  The serine family includes synthesis of all four of these amino acids. 
A)  Serine. 
B)  Glycine. 
C)  Cysteine. 
D)  Methionine. 
E)  The serine family includes synthesis of all four of these amino acids.

Question 12

Nitrogenase uses which of the following cofactors?

Accepted Answer

A)  molybdenum-iron-sulfur complex 
B)  biotin 
C)  pyridoxal phosphate 
D)  thiamine pyrophosphate 
E)  none of these 
A)  molybdenum-iron-sulfur complex 
B)  biotin 
C)  pyridoxal phosphate 
D)  thiamine pyrophosphate 
E)  none of these

Question 13

Which of the following are all essential amino acids in humans?

Accepted Answer

A)  leucine, lysine, valine 
B)  methionine, threonine, serine 
C)  arginine, histidine, cysteine 
D)  glutamate, glutamine, arginine 
E)  valine, isoleucine, glycine 
A)  leucine, lysine, valine 
B)  methionine, threonine, serine 
C)  arginine, histidine, cysteine 
D)  glutamate, glutamine, arginine 
E)  valine, isoleucine, glycine

Question 14

Essential amino acids cannot be synthesized in sufficient quantities within the human body.

Accepted Answer

A) True 
 B)False

Question 15

Some amino acids can only be made in small quantities in humans and must be supplemented in the diet in children or during repair of injured tissue.

Accepted Answer

A) True 
 B)False

Question 16

By a simple transamination reaction, intermediates in glycolysis or the Kreb's Cycle can be converted in one step to all of these amino acids, except:

Accepted Answer

A)  Alanine. 
B)  Aspartic Acid 
C)  Glutamic Acid. 
D)  Serine. 
E)  All of these amino acids are only one step away from the major metabolic pathways. 
A)  Alanine. 
B)  Aspartic Acid 
C)  Glutamic Acid. 
D)  Serine. 
E)  All of these amino acids are only one step away from the major metabolic pathways.

Question 17

The conversion of uracil to thymine requires

Accepted Answer

A)  a one-carbon transfer with S-adenosylmethionine as the donor 
B)  a one-carbon transfer with tetrahydrofolate as the donor 
C)  a one-carbon transfer with biotin as the donor 
D)  a one-carbon transfer with oxaloacetate as the donor 
A)  a one-carbon transfer with S-adenosylmethionine as the donor 
B)  a one-carbon transfer with tetrahydrofolate as the donor 
C)  a one-carbon transfer with biotin as the donor 
D)  a one-carbon transfer with oxaloacetate as the donor

Question 18

Which of the following is not associated with pyrimidine synthesis?

Accepted Answer

A)  Synthesis of the base while ribose is attached. 
B)  Stimulation of synthesis by purines. 
C)  An orotic acid intermediate. 
D)  Inhibition by pyrimidines. 
E)  All of these are features of pyrimidine synthesis. 
A)  Synthesis of the base while ribose is attached. 
B)  Stimulation of synthesis by purines. 
C)  An orotic acid intermediate. 
D)  Inhibition by pyrimidines. 
E)  All of these are features of pyrimidine synthesis.

Exam 23: The Metabolism of Nitrogen

Denitrification is carried out by

How many ATP equivalents are required to produce one molecule of urea from ammonia and aspartate?

Carbamoyl phosphate is made in both the mitochondria and the cytosol, because it is used in the synthesis of several different molecules which are made in either of the compartments.

Cancer treatments which disrupt the function of folic acid have significant side effects, since this therapy also affects the growth of such rapidly dividing tissues as all of the following, except:

How many electrons are required for the reduction of one nitrogen molecule (N2) to two molecules of ammonia (NH3) and molecule of hydrogen (H2)?

In nitrogen fixation, the chemical change is

Many antibiotics, especially for viruses and cancer therapy involve inhibition of folic acid reactions, especially because folic acid is essential for this reaction:

In the synthesis of pyrimidine nucleotides, the ring system formed just before the attachment of PRPP is

Fluorouracil is an effective inhibitor of

If an amino acid is ketogenic, then it:

The serine family of amino acids includes synthesis of all the following amino acids, except:

Nitrogenase uses which of the following cofactors?

Which of the following are all essential amino acids in humans?

Essential amino acids cannot be synthesized in sufficient quantities within the human body.

Some amino acids can only be made in small quantities in humans and must be supplemented in the diet in children or during repair of injured tissue.

By a simple transamination reaction, intermediates in glycolysis or the Kreb's Cycle can be converted in one step to all of these amino acids, except:

The conversion of uracil to thymine requires

Which of the following is not associated with pyrimidine synthesis?

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

How many electrons are required for the reduction of one nitrogen molecule (N₂) to two molecules of ammonia (NH₃) and molecule of hydrogen (H₂)?