Question 1

Which of the following is not a characteristic of pyridoxal in its active form?

Accepted Answer

A)  It is covalently bonded to its enzyme. 
B)  It requires being attached to a phosphate group. 
C)  It bonds to an amine group through by means of the phosphate group. 
D)  It has a particularly reactive carbonyl group. 
A)  It is covalently bonded to its enzyme. 
B)  It requires being attached to a phosphate group. 
C)  It bonds to an amine group through by means of the phosphate group. 
D)  It has a particularly reactive carbonyl group.

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

Isoleucine,leucine and valine are all formed from the same amino acid root,aspartic acid.

Accepted Answer

A) True 
 B)False

Question 4

How many ATP are required for the production of two ammonia molecules (NH3) from one nitrogen molecule (N2)?

Accepted Answer

A)  2 ATP. 
B)  4 ATP. 
C)  8 ATP. 
D)  16 ATP. 
E)  32 ATP. 
A)  2 ATP. 
B)  4 ATP. 
C)  8 ATP. 
D)  16 ATP. 
E)  32 ATP.

Question 5

One way in which the anabolism of pyrimidine nucleotides differs from that of purine nucleotides is that

Accepted Answer

A)  the pyrimidine ring is assembled before being bonded to the ribose phosphate, whereas the purine ring is bonded to the ribose phosphate as it is formed 
B)  there is no feedback inhibition in the anabolism of pyrimidine nucleotides, while feedback inhibition is important in the synthesis of purine nucleotides 
C)  glycine appears in the pathway for formation of pyrimidine nucleotides but not in that for the formation of purine nucleotides 
D)  argininosuccinate is a key intermediate in pyrimidine biosynthesis 
A)  the pyrimidine ring is assembled before being bonded to the ribose phosphate, whereas the purine ring is bonded to the ribose phosphate as it is formed 
B)  there is no feedback inhibition in the anabolism of pyrimidine nucleotides, while feedback inhibition is important in the synthesis of purine nucleotides 
C)  glycine appears in the pathway for formation of pyrimidine nucleotides but not in that for the formation of purine nucleotides 
D)  argininosuccinate is a key intermediate in pyrimidine biosynthesis

Question 6

Which of the following amino acids is not glucogenic?

Accepted Answer

A)  Glycine. 
B)  Alanine. 
C)  Aspartic Acid. 
D)  Leucine. 
E)  All of these amino acids are glucogenic. 
A)  Glycine. 
B)  Alanine. 
C)  Aspartic Acid. 
D)  Leucine. 
E)  All of these amino acids are glucogenic.

Question 7

The sulfur group in cysteine arises from the same source in plants,animals and bacteria.

Accepted Answer

A) True 
 B)False

Question 8

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 9

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 10

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 11

Nitrification is the conversion of

Accepted Answer

A)  nitrogen gas to nitrate. 
B)  nitrogen gas to ammonia. 
C)  nitrate to ammonia. 
D)  nitrate to nitrogen gas. 
E)  ammonia to nitrogen gas. 
A)  nitrogen gas to nitrate. 
B)  nitrogen gas to ammonia. 
C)  nitrate to ammonia. 
D)  nitrate to nitrogen gas. 
E)  ammonia to nitrogen gas.

Question 12

The conversion of a-ketoglutarate to glutamate is

Accepted Answer

A)  a transamination. 
B)  a reductive amination. 
C)  an amidation. 
D)  an oxidation. 
A)  a transamination. 
B)  a reductive amination. 
C)  an amidation. 
D)  an oxidation.

Question 13

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 14

Which best describes the synthesis of purine nucleotides?

Accepted Answer

A)  The basic ring structure, inosine, is synthesized first and then linked to ribose. This is then modified to produce either GMP or AMP. 
B)  The basic ring structure, orotate, is synthesized stepwise on ribose. This is then modified to produce either GMP or AMP. 
C)  The basic ring structure, inosine, is synthesized stepwise on ribose. This is then modified to produce either GMP or AMP. 
D)  The basic ring structure, orotate, is synthesized first and then linked to ribose. This is then modified to produce either UMP or CMP. 
A)  The basic ring structure, inosine, is synthesized first and then linked to ribose. This is then modified to produce either GMP or AMP. 
B)  The basic ring structure, orotate, is synthesized stepwise on ribose. This is then modified to produce either GMP or AMP. 
C)  The basic ring structure, inosine, is synthesized stepwise on ribose. This is then modified to produce either GMP or AMP. 
D)  The basic ring structure, orotate, is synthesized first and then linked to ribose. This is then modified to produce either UMP or CMP.

Question 15

In animals,the synthesis of cysteine involves all of the following,except:

Accepted Answer

A)  Addition of a carbon group to glycine. 
B)  Transfer of the sulfur group from methionine. 
C)  An intermediate of homocysteine. 
D)  Participation of ATP. 
E)  All of these reactions are involved in synthesizing cysteine in animals. 
A)  Addition of a carbon group to glycine. 
B)  Transfer of the sulfur group from methionine. 
C)  An intermediate of homocysteine. 
D)  Participation of ATP. 
E)  All of these reactions are involved in synthesizing cysteine in animals.

Question 16

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 
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

Question 17

High protein diets for humans result in the following.

Accepted Answer

A)  Increased nitrogen metabolism. 
B)  A negative nitrogen balance for the body. 
C)  Increased demand for water in the diet. 
D)  Both increased nitrogen metabolism and need for water. 
E)  All of these are consequences of high protein diets. 
A)  Increased nitrogen metabolism. 
B)  A negative nitrogen balance for the body. 
C)  Increased demand for water in the diet. 
D)  Both increased nitrogen metabolism and need for water. 
E)  All of these are consequences of high protein diets.

Question 18

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.

Exam 23: The Metabolism of Nitrogen

Which of the following is not a characteristic of pyridoxal in its active form?

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

Isoleucine,leucine and valine are all formed from the same amino acid root,aspartic acid.

How many ATP are required for the production of two ammonia molecules (NH3) from one nitrogen molecule (N2)?

One way in which the anabolism of pyrimidine nucleotides differs from that of purine nucleotides is that

Which of the following amino acids is not glucogenic?

The sulfur group in cysteine arises from the same source in plants,animals and bacteria.

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:

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.

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

Nitrification is the conversion of

The conversion of a-ketoglutarate to glutamate is

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

Which best describes the synthesis of purine nucleotides?

In animals,the synthesis of cysteine involves all of the following,except:

If an amino acid is ketogenic,then it:

High protein diets for humans result in the following.

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:

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 ATP are required for the production of two ammonia molecules (NH₃) from one nitrogen molecule (N₂)?