Question 1

Which of the following is not associated with purine synthesis?

Accepted Answer

A)  Synthesis of the base while ribose is attached. 
B)  Stimulation of ATP synthesis by GTP and of GTP synthesis by ATP 
C)  An Inosine intermediate. 
D)  Inhibition by pyrimidines. 
E)  All of these are features of purine synthesis. 
A)  Synthesis of the base while ribose is attached. 
B)  Stimulation of ATP synthesis by GTP and of GTP synthesis by ATP 
C)  An Inosine intermediate. 
D)  Inhibition by pyrimidines. 
E)  All of these are features of purine synthesis. D

Question 2

Which of the following is not true regarding ammonia and fertilizers?

Accepted Answer

A)  Ammonia gas is seldom an effective plant fertilizer, since it is usually consumed by the bacteria in the soil. 
B)  Many fertilizers are made from ammonia synthesized by the Haber process 
C)  Researchers are looking for ways to incorporate the genes for nitrogenase into crop plants so that not as much fertilizer is needed 
D)  Both ammonium and nitrate ions are frequently used in fertilizers 
A)  Ammonia gas is seldom an effective plant fertilizer, since it is usually consumed by the bacteria in the soil. 
B)  Many fertilizers are made from ammonia synthesized by the Haber process 
C)  Researchers are looking for ways to incorporate the genes for nitrogenase into crop plants so that not as much fertilizer is needed 
D)  Both ammonium and nitrate ions are frequently used in fertilizers B

Question 3

How is cancer chemotherapy related to purine biosyntheis?

Accepted Answer

A)  rapidly dividing cells require more purine biosynthesis and some chemotherapy drugs inhibit a key enzyme in purine biosynthesis 
B)  aminopterin is a good chemotherapy drug because it inhibits aspartate transcarbamoylase 
C)  cancer cells lack folic acid, and chemotherapy drugs like sulfanamide act by overproducing folic acid, which is then poisonous to the cancer cells 
D)  none of these 
A)  rapidly dividing cells require more purine biosynthesis and some chemotherapy drugs inhibit a key enzyme in purine biosynthesis 
B)  aminopterin is a good chemotherapy drug because it inhibits aspartate transcarbamoylase 
C)  cancer cells lack folic acid, and chemotherapy drugs like sulfanamide act by overproducing folic acid, which is then poisonous to the cancer cells 
D)  none of these A

Question 4

A characteristic feature of feedback inhibition is that

Accepted Answer

A)  it is wasteful of energy and reducing power in anabolic pathways 
B)  it leads to buildup of the end products of anabolic pathways 
C)  it seldom occurs in the metabolism of compounds of nitrogen 
D)  it commonly appears in biosynthesis of amino acids 
E)  it always involves the inhibition of the first step of a pathway 
A)  it is wasteful of energy and reducing power in anabolic pathways 
B)  it leads to buildup of the end products of anabolic pathways 
C)  it seldom occurs in the metabolism of compounds of nitrogen 
D)  it commonly appears in biosynthesis of amino acids 
E)  it always involves the inhibition of the first step of a pathway

Question 5

Orotic acid is synthesized from

Accepted Answer

A)  glycine and carbamoyl phosphate. 
B)  arginine and carbamoyl phosphate. 
C)  aspartic acid and carbamoyl phosphate. 
D)  aspartic acid and glutamine. 
A)  glycine and carbamoyl phosphate. 
B)  arginine and carbamoyl phosphate. 
C)  aspartic acid and carbamoyl phosphate. 
D)  aspartic acid and glutamine.

Question 6

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 7

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 8

What intermediate of the TCA cycle is produced from aspartic acid during the urea cycle, synthesis of IMP, and conversion from IMP to adenosine?

Accepted Answer

A)  fumarate 
B)  malate 
C)  α-ketoglutarate 
D)  succinate 
A)  fumarate 
B)  malate 
C)  α-ketoglutarate 
D)  succinate

Question 9

Pyridoxal phosphate is involved in which of the following reactions?

Accepted Answer

A)  transaminations 
B)  decarboxylations 
C)  racemizations 
D)  movement of hydroxymethyl groups 
E)  all of these 
A)  transaminations 
B)  decarboxylations 
C)  racemizations 
D)  movement of hydroxymethyl groups 
E)  all of these

Question 10

Which of the following is not a carrier of one-carbon groups?

Accepted Answer

A)  S-adenosylmethionine 
B)  biotin 
C)  tetrahydrofolate 
D)  thiamine pyrophosphate 
A)  S-adenosylmethionine 
B)  biotin 
C)  tetrahydrofolate 
D)  thiamine pyrophosphate

Question 11

The carbon skeleton used to make serine is:

Accepted Answer

A)  3-phosphoglycerate 
B)  glutamate 
C)  á-ketoglutarate 
D)  oxaloacetate 
E)  pyruvate 
A)  3-phosphoglycerate 
B)  glutamate 
C)  á-ketoglutarate 
D)  oxaloacetate 
E)  pyruvate

Question 12

The urea cycle is linked to the citric acid cycle by

Accepted Answer

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

Question 13

Which of the following is not a component of the nitrogenase complex?

Accepted Answer

A)  a molybdenum complex 
B)  a nonheme iron-sulfur protein (Fe protein) 
C)  ferredoxin 
D)  pyridoxal phosphate 
A)  a molybdenum complex 
B)  a nonheme iron-sulfur protein (Fe protein) 
C)  ferredoxin 
D)  pyridoxal phosphate

Question 14

Which of the following is not an interconversion of nitrogen performed by living organisms?

Accepted Answer

A)  Fixation of atmospheric nitrogen into ammonia. 
B)  Fixation of atmospheric nitrogen into nitrate. 
C)  Nitrification of soil nitrate into ammonia 
D)  Denitrification of nitrogen oxides to gaseous nitrogen. 
E)  All of these are common bioconversions in the nitrogen cycle. 
A)  Fixation of atmospheric nitrogen into ammonia. 
B)  Fixation of atmospheric nitrogen into nitrate. 
C)  Nitrification of soil nitrate into ammonia 
D)  Denitrification of nitrogen oxides to gaseous nitrogen. 
E)  All of these are common bioconversions in the nitrogen cycle.

Question 15

The conversion of α-ketoglutarate to glutamate is

Accepted Answer

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

Question 16

A coenzyme frequently encountered in transamination reactions is

Accepted Answer

A)  tetrahydrofolate. 
B)  pyridoxal phosphate. 
C)  thiamine pyrophosphate. 
D)  biotin. 
A)  tetrahydrofolate. 
B)  pyridoxal phosphate. 
C)  thiamine pyrophosphate. 
D)  biotin.

Question 17

The carbon skeletons of many amino acids can be used to replenish the intermediates of the citric acid cycle.

Accepted Answer

A) True 
 B)False

Question 18

High protein foods are not advisable for the long distance runner during a race because they increase the need for water and for urination.

Accepted Answer

A) True 
 B)False

Question 19

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 20

Enzymes which carry out one-carbon transfers can use any of these compounds, except:

Accepted Answer

A)  Biotin 
B)  Pyridoxal 
C)  Folic Acid 
D)  S-adenosylmethionine 
E)  All of these can carry out one-carbon transfers. 
A)  Biotin 
B)  Pyridoxal 
C)  Folic Acid 
D)  S-adenosylmethionine 
E)  All of these can carry out one-carbon transfers.

Exam 23: The Metabolism of Nitrogen

Which of the following is not associated with purine synthesis?

Which of the following is not true regarding ammonia and fertilizers?

How is cancer chemotherapy related to purine biosyntheis?

A characteristic feature of feedback inhibition is that

Orotic acid is synthesized from

High protein diets for humans result in the following.

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

What intermediate of the TCA cycle is produced from aspartic acid during the urea cycle, synthesis of IMP, and conversion from IMP to adenosine?

Pyridoxal phosphate is involved in which of the following reactions?

Which of the following is not a carrier of one-carbon groups?

The carbon skeleton used to make serine is:

The urea cycle is linked to the citric acid cycle by

Which of the following is not a component of the nitrogenase complex?

Which of the following is not an interconversion of nitrogen performed by living organisms?

The conversion of α-ketoglutarate to glutamate is

A coenzyme frequently encountered in transamination reactions is

The carbon skeletons of many amino acids can be used to replenish the intermediates of the citric acid cycle.

High protein foods are not advisable for the long distance runner during a race because they increase the need for water and for urination.

Which of the following amino acids is not glucogenic?

Enzymes which carry out one-carbon transfers can use any of these compounds, 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

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