Question 1

Which base is not found in DNA?

Accepted Answer

A)  Thymine 
B)  Adenine 
C)  Uracil 
D)  Guanine 
E)  Cytosine 
A)  Thymine 
B)  Adenine 
C)  Uracil 
D)  Guanine 
E)  Cytosine C

Question 2

Which protein structure is not destroyed by denaturation?

Accepted Answer

A)  Primary 
B)  Secondary 
C)  Tertiary 
D)  Quaternary 
E)  Both a and b 
A)  Primary 
B)  Secondary 
C)  Tertiary 
D)  Quaternary 
E)  Both a and b A

Question 3

How do competitive and noncompetitive enzyme inhibitors differ?

Accepted Answer

A)  Competitive inhibitors bind to the active site,whereas noncompetitive inhibitors may change the shape of the active site. 
B)  Competitive inhibitors have a higher energy of activation than noncompetitive inhibitors. 
C)  Competitive and noncompetitive inhibitors function at different pH values. 
D)  Noncompetitive inhibitors contain magnesium,whereas competitive inhibitors contain iron. 
E)  Noncompetitive inhibitors are reversible,whereas competitive inhibitors are irreversible. 
A)  Competitive inhibitors bind to the active site,whereas noncompetitive inhibitors may change the shape of the active site. 
B)  Competitive inhibitors have a higher energy of activation than noncompetitive inhibitors. 
C)  Competitive and noncompetitive inhibitors function at different pH values. 
D)  Noncompetitive inhibitors contain magnesium,whereas competitive inhibitors contain iron. 
E)  Noncompetitive inhibitors are reversible,whereas competitive inhibitors are irreversible. A

Question 4

You add substrate to an enzyme reaction until the rate no longer changes,and then,upon raising the temperature,you see the reaction rate go up even further.You conclude that

Accepted Answer

A)  increasing the temperature has activated an inhibitor. 
B)  the saturation rate was not determined at the optimal temperature. 
C)  the increased temperature has removed a prosthetic group,thus activating the enzyme. 
D)  the reaction is regulated by feedback inhibition. 
E)  the subunits of the enzyme have denatured. 
A)  increasing the temperature has activated an inhibitor. 
B)  the saturation rate was not determined at the optimal temperature. 
C)  the increased temperature has removed a prosthetic group,thus activating the enzyme. 
D)  the reaction is regulated by feedback inhibition. 
E)  the subunits of the enzyme have denatured.

Question 5

Which characteristic allows cells to control their internal environment?

Accepted Answer

A)  Their ability to control the synthesis of an enzyme 
B)  Their ability to control the activity of an enzyme 
C)  The balance of ions in the external environment 
D)  The light-dark cycle 
E)  Both a and b 
A)  Their ability to control the synthesis of an enzyme 
B)  Their ability to control the activity of an enzyme 
C)  The balance of ions in the external environment 
D)  The light-dark cycle 
E)  Both a and b

Question 6

In a chemical reaction,transition-state species have free energies that are

Accepted Answer

A)  lower than either the reactants or the products. 
B)  higher than either the reactants or the products. 
C)  lower than the reactants,but higher than the products. 
D)  higher than the reactants,but lower than the products. 
E)  lower than the reactants,but the same as the products. 
A)  lower than either the reactants or the products. 
B)  higher than either the reactants or the products. 
C)  lower than the reactants,but higher than the products. 
D)  higher than the reactants,but lower than the products. 
E)  lower than the reactants,but the same as the products.

Question 7

A $\beta$ pleated sheet organization in a polypeptide chain is an example of _______ structure.

Accepted Answer

A)  primary 
B)  secondary 
C)  tertiary 
D)  quaternary 
E)  coiled 
A)  primary 
B)  secondary 
C)  tertiary 
D)  quaternary 
E)  coiled

Question 8

The shape of a folded protein is determined by

Accepted Answer

A)  its tertiary structure. 
B)  the sequence of its amino acids. 
C)  whether the peptide bonds have $\alpha$or $\beta$ linkages. 
D)  the number of peptide bonds. 
E)  the base-pairing rules. 
A)  its tertiary structure. 
B)  the sequence of its amino acids. 
C)  whether the peptide bonds have $\alpha$or $\beta$ linkages. 
D)  the number of peptide bonds. 
E)  the base-pairing rules.

Question 9

Which statement about the feedback inhibition of enzymes is false?

Accepted Answer

A)  It is usually exerted through allosteric effects. 
B)  It is directed at the enzyme that catalyzes the commitment step in a metabolic pathway. 
C)  It affects the rate of a reaction,not the concentration of the enzyme. 
D)  It acts by permanently modifying the active site. 
E)  It is an example of reversible inhibition. 
A)  It is usually exerted through allosteric effects. 
B)  It is directed at the enzyme that catalyzes the commitment step in a metabolic pathway. 
C)  It affects the rate of a reaction,not the concentration of the enzyme. 
D)  It acts by permanently modifying the active site. 
E)  It is an example of reversible inhibition.

Question 10

Which statement about purines and pyrimidines is true?

Accepted Answer

A)  Purines include the bases of cytosine and thymine;pyrimidines include the bases of adenine and guanine. 
B)  Pyrimidines are found in RNA,whereas purines are found in DNA. 
C)  Purines consist of hydrogen,carbon,oxygen,and nitrogen,whereas pyrimidines have phosphorus,hydrogen,carbon,oxygen,and nitrogen. 
D)  Purines have only single bonds in their structure,whereas pyrimidines have both single and double bonds. 
E)  Purines are double-ring structures,whereas pyrimidines are single-ring structures. 
A)  Purines include the bases of cytosine and thymine;pyrimidines include the bases of adenine and guanine. 
B)  Pyrimidines are found in RNA,whereas purines are found in DNA. 
C)  Purines consist of hydrogen,carbon,oxygen,and nitrogen,whereas pyrimidines have phosphorus,hydrogen,carbon,oxygen,and nitrogen. 
D)  Purines have only single bonds in their structure,whereas pyrimidines have both single and double bonds. 
E)  Purines are double-ring structures,whereas pyrimidines are single-ring structures.

Question 11

Amino acids can be classified by the

Accepted Answer

A)  number of monosaccharides they contain. 
B)  number of carbon-carbon double bonds in their fatty acids. 
C)  number of peptide bonds they can form. 
D)  number of disulfide bridges they can form. 
E)  characteristics of their side chains. 
A)  number of monosaccharides they contain. 
B)  number of carbon-carbon double bonds in their fatty acids. 
C)  number of peptide bonds they can form. 
D)  number of disulfide bridges they can form. 
E)  characteristics of their side chains.

Question 12

Cytosine is a pyrimidine that forms three hydrogen bonds.Uracil is also a pyrimidine.Based on this information,one can conclude that uracil forms _______ hydrogen bonds and pairs with _______.

Accepted Answer

A)  three;guanine (a two-bond pyrimidine) 
B)  three;adenine (a three-bond purine) 
C)  three;guanine (a three-bond purine) 
D)  two;adenine (a two-bond purine) 
E)  two;thymine (a two-bond pyrimidine) 
A)  three;guanine (a two-bond pyrimidine) 
B)  three;adenine (a three-bond purine) 
C)  three;guanine (a three-bond purine) 
D)  two;adenine (a two-bond purine) 
E)  two;thymine (a two-bond pyrimidine)

Question 13

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate $\rightarrow$   1,3-diphosphoglycerate.The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)

Accepted Answer

A)  transition state. 
B)  activation groove. 
C)  catalyst. 
D)  enzyme-substrate complex. 
E)  energy barrier. 
A)  transition state. 
B)  activation groove. 
C)  catalyst. 
D)  enzyme-substrate complex. 
E)  energy barrier.

Question 14

Two complementary nucleotides are connected by _______ bonds.

Accepted Answer

A)  hydrogen 
B)  ionic 
C)  peptide 
D)  phosphodiester 
E)  covalent 
A)  hydrogen 
B)  ionic 
C)  peptide 
D)  phosphodiester 
E)  covalent

Question 15

Noncovalent binding of substrate to the active site of an enzyme is

Accepted Answer

A)  reversible. 
B)  irreversible. 
C)  noncompetitive. 
D)  coupled. 
E)  allosteric. 
A)  reversible. 
B)  irreversible. 
C)  noncompetitive. 
D)  coupled. 
E)  allosteric.

Question 16

In order for a reaction to occur,many enzymes require ATP and ADP,which temporarily bind to and then release from the substrate.ATP and ADP are therefore considered to be

Accepted Answer

A)  a side chain. 
B)  coenzymes. 
C)  substrates. 
D)  a prosthetic group. 
E)  cocatalysts. 
A)  a side chain. 
B)  coenzymes. 
C)  substrates. 
D)  a prosthetic group. 
E)  cocatalysts.

Question 17

The enzyme glucose oxidase binds the 6-carbon sugar glucose and catalyzes its conversion to glucono-1,5-lactone.Mannose is also a 6-carbon sugar,but glucose oxidase cannot bind mannose.The specificity of glucose oxidase is based on the

Accepted Answer

A)  free energy of the transition state. 
B)  activation energy of the reaction. 
C)  change in free energy of the reaction. 
D)  three-dimensional shape and structure of the active site. 
E)  rate constant of the reaction. 
A)  free energy of the transition state. 
B)  activation energy of the reaction. 
C)  change in free energy of the reaction. 
D)  three-dimensional shape and structure of the active site. 
E)  rate constant of the reaction.

Question 18

The process by which a final product acts as an inhibitor to the enzyme that catalyzes the commitment step in a metabolic pathway is called

Accepted Answer

A)  feedback activation. 
B)  feedback inhibition. 
C)  positive feedback. 
D)  concerted activation. 
E)  competitive inhibition. 
A)  feedback activation. 
B)  feedback inhibition. 
C)  positive feedback. 
D)  concerted activation. 
E)  competitive inhibition.

Question 19

How many different types of tetrapeptides (molecules with four linked amino acids)can be made from the 20 common amino acids?

Accepted Answer

A)  4 
B)  80 
C)  256 
D)  8,000 
E)  160,000 
A)  4 
B)  80 
C)  256 
D)  8,000 
E)  160,000

Question 20

Enzymes are sensitive to

Accepted Answer

A)  temperature. 
B)  pH. 
C)  irreversible inhibitors such as DIPF. 
D)  allosteric effectors. 
E)  All of the above 
A)  temperature. 
B)  pH. 
C)  irreversible inhibitors such as DIPF. 
D)  allosteric effectors. 
E)  All of the above

Exam 3: Nucleic Acids, Proteins, and Enzymes

Which base is not found in DNA?

Which protein structure is not destroyed by denaturation?

How do competitive and noncompetitive enzyme inhibitors differ?

You add substrate to an enzyme reaction until the rate no longer changes,and then,upon raising the temperature,you see the reaction rate go up even further.You conclude that

Which characteristic allows cells to control their internal environment?

In a chemical reaction,transition-state species have free energies that are

A β\betaβ pleated sheet organization in a polypeptide chain is an example of _______ structure.

The shape of a folded protein is determined by

Which statement about the feedback inhibition of enzymes is false?

Which statement about purines and pyrimidines is true?

Amino acids can be classified by the

Cytosine is a pyrimidine that forms three hydrogen bonds.Uracil is also a pyrimidine.Based on this information,one can conclude that uracil forms _______ hydrogen bonds and pairs with _______.

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate →\rightarrow→ 1,3-diphosphoglycerate.The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)

Two complementary nucleotides are connected by _______ bonds.

Noncovalent binding of substrate to the active site of an enzyme is

In order for a reaction to occur,many enzymes require ATP and ADP,which temporarily bind to and then release from the substrate.ATP and ADP are therefore considered to be

The enzyme glucose oxidase binds the 6-carbon sugar glucose and catalyzes its conversion to glucono-1,5-lactone.Mannose is also a 6-carbon sugar,but glucose oxidase cannot bind mannose.The specificity of glucose oxidase is based on the

The process by which a final product acts as an inhibitor to the enzyme that catalyzes the commitment step in a metabolic pathway is called

How many different types of tetrapeptides (molecules with four linked amino acids)can be made from the 20 common amino acids?

Enzymes are sensitive to

Introduction

The Chemistry and Energy of Life

Cells: the Working Units of Life

Cell Membranes and Signaling

Pathways That Harvest and Store Chemical Energy

The Cell Cycle and Cell Division

Inheritance, Genes, and Chromosomes

DNA and Its Role in Heredity

From Dna to Protein: Gene Expression

Regulation of Gene Expression

Genomes

Biotechnology

Genes, Development, and Evolution

Processes of Evolution

Reconstructing and Using Phylogenies

Speciation

The History of Life on Earth

Bacteria, Archaea, and Viruses

The Origin and Diversification of Eukaryotes

The Evolution of Plants

The Evolution and Diversity of Fungi

Animal Origins and Diversity

The Plant Body

Plant Nutrition and Transport

Plant Growth and Development

Reproduction of Flowering Plants

Plants in the Environment

Fundamentals of Animal Function

Nutrition and Digestion

Breathing

Circulation

Muscle and Movement

Neurons, Sense Organs, and Nervous Systems

Nervous and Endocrine Control

Water and Salts: Excretion

Animal Reproduction

Animal Development

Immunology: Animal Defense Systems

Animal Behavior

The Distribution of Earths Ecological Systems

Populations

Ecological and Evolutionary Consequences of Interactions Within and Among Species

Ecological Communities

The Global Ecosystem

Filters

A $\beta$ pleated sheet organization in a polypeptide chain is an example of _______ structure.

Cytosine is a pyrimidine that forms three hydrogen bonds.Uracil is also a pyrimidine.Based on this information,one can conclude that uracil forms _ hydrogen bonds and pairs with _.

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate $\rightarrow$ 1,3-diphosphoglycerate.The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)