Question 1

Why does the existence of ribozymes offer a possible solution to the question of whether nucleic acids or proteins appeared first in evolution?

Accepted Answer

Because nucleic acids contain the requir

Question 2

If an enzyme is bound by an allosteric activator , the enzyme will convert from a low-affinity state to a high-affinity state.

Accepted Answer

A) True 
 B)False

Question 3

Ribozymes are ____.

Accepted Answer

A)  RNA catalysts 
B)  proteins that catalyze RNA synthesis 
C)  RNA molecules that slow the rate of protein synthesis 
D)  the products of RNA degradation 
E)  amino acids that catalyze RNA synthesis 
A)  RNA catalysts 
B)  proteins that catalyze RNA synthesis 
C)  RNA molecules that slow the rate of protein synthesis 
D)  the products of RNA degradation 
E)  amino acids that catalyze RNA synthesis

Question 4

In order to prevent hair loss in men, one popular treatment is to use an inhibitor of the enzyme that converts testosterone to a different androgen (DHT). The inhibitors are steroids similar to testosterone that cannot be converted into DHT. How would you classify this type of inhibition?

Accepted Answer

A)  competitive inhibition 
B)  noncompetitive inhibition 
C)  allosteric inhibition 
D)  feedback inhibition 
E)  ionic inhibition 
A)  competitive inhibition 
B)  noncompetitive inhibition 
C)  allosteric inhibition 
D)  feedback inhibition 
E)  ionic inhibition

Question 5

ATP synthesis is exergonic .

Accepted Answer

A) True 
 B)False

Question 6

Ribozymes are enzymes.

Accepted Answer

A) True 
 B)False

Question 7

Answer the question using the accompanying graph. Which portion of the graph shows the free energy of the reaction?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  W + X 
E)  Y + Z 
A)  A 
B)  B 
C)  C 
D)  W + X 
E)  Y + Z

Question 8

According to the first law of thermodynamics, ____.

Accepted Answer

A)  matter can be created and destroyed 
B)  matter only changes forms 
C)  energy can be created and destroyed 
D)  energy only changes forms 
E)  matter and energy can be interconverted 
A)  matter can be created and destroyed 
B)  matter only changes forms 
C)  energy can be created and destroyed 
D)  energy only changes forms 
E)  matter and energy can be interconverted

Question 9

Enzymes ____.

Accepted Answer

A)  change the rate of a reaction 
B)  change the direction of a reaction 
C)  change the free energy of a reaction 
D)  are used up in a reaction 
E)  are present in concentrations approaching their substrates' concentrations 
A)  change the rate of a reaction 
B)  change the direction of a reaction 
C)  change the free energy of a reaction 
D)  are used up in a reaction 
E)  are present in concentrations approaching their substrates' concentrations

Question 10

The term that best describes all of the chemical reactions of a cell, including acquisition and use of molecules and energy, is ____.

Accepted Answer

A)  metabolism 
B)  anabolism 
C)  catabolism 
D)  energy budget 
E)  thermodynamics 
A)  metabolism 
B)  anabolism 
C)  catabolism 
D)  energy budget 
E)  thermodynamics

Question 11

Identify the exergonic reaction in the list below.

Accepted Answer

A)  burning wood for a campfire 
B)  folding laundry 
C)  building a tower out of blocks 
D)  synthesizing a protein 
E)  storing the third slice of pie in the form of fat 
A)  burning wood for a campfire 
B)  folding laundry 
C)  building a tower out of blocks 
D)  synthesizing a protein 
E)  storing the third slice of pie in the form of fat

Question 12

What is the significance of activation energy?

Accepted Answer

Activation energy is the initi

Question 13

Energy from ATP is transferred to the reactant of an endergonic reaction by addition of a(n) _____ group to that molecule.

Accepted Answer

A)  nitrate 
B)  ribose 
C)  deoxyribose 
D)  acetyl 
E)  phosphate 
A)  nitrate 
B)  ribose 
C)  deoxyribose 
D)  acetyl 
E)  phosphate

Question 14

Zhang and Cech's experiments confirmed which feature of ribozyme activity?

Accepted Answer

A)  Ribozymes inhibit rates of biological reactions. 
B)  Ribozymes catalyze formation of bonds between amino acids in protein synthesis. 
C)  Ribozymes catalyze formation of the fundamental linkage tying nucleic acids to proteins. 
D)  Ribozymes can link nucleic acids together even if their proteins are removed. 
E)  Ribozymes provide a possible solution to the question of whether proteins or nucleic acids appeared first in evolution. 
A)  Ribozymes inhibit rates of biological reactions. 
B)  Ribozymes catalyze formation of bonds between amino acids in protein synthesis. 
C)  Ribozymes catalyze formation of the fundamental linkage tying nucleic acids to proteins. 
D)  Ribozymes can link nucleic acids together even if their proteins are removed. 
E)  Ribozymes provide a possible solution to the question of whether proteins or nucleic acids appeared first in evolution.

Question 15

In an exothermic reaction, ____.

Accepted Answer

A)  ATP is phosphorylated 
B)  heat energy is absorbed 
C)  the products have less potential energy than the reactants 
D)  the reactants have less potential energy than the products 
E)  H (enthalpy) = 0 
A)  ATP is phosphorylated 
B)  heat energy is absorbed 
C)  the products have less potential energy than the reactants 
D)  the reactants have less potential energy than the products 
E)  H (enthalpy) = 0

Question 16

Enzymes are ____ catalysts.

Accepted Answer

A)  protein 
B)  lipid 
C)  nucleic acid 
D)  inorganic 
E)  ionic 
A)  protein 
B)  lipid 
C)  nucleic acid 
D)  inorganic 
E)  ionic

Question 17

Which reaction is most likely to have more products than reactants when it reaches equilibrium?

Accepted Answer

A)  DG = -25 kcal/mol 
B)  DG = -50 kcal/mol 
C)  DG = -75 kcal/mol 
D)  DG = -100 kcal/mol 
E)  They will all have the same ratio of products to reactants regardless of the DG value. 
A)  DG = -25 kcal/mol 
B)  DG = -50 kcal/mol 
C)  DG = -75 kcal/mol 
D)  DG = -100 kcal/mol 
E)  They will all have the same ratio of products to reactants regardless of the DG value.

Question 18

Figure 6.3
In the accompanying figure, why does the curve sharply drop after approximately 45°C instead of mirroring the slope of the line going from 0-40°C?

Accepted Answer

A)  At high temperatures, the reactions proceed so quickly that enzymes are no longer helpful or required. 
B)  This is true of all catalysts and is not due to any special features of enzymes. 
C)  The kinetic energy of the reactants is so great that it destabilizes the enzyme and diminishes the enzyme's activity. 
D)  The kinetic energy of the reactants is lower than that of the products, forcing a change in enzyme activity. 
E)  The enzyme begins to denature above a certain temperature, eliminating all catalytic activity of the protein. 
A)  At high temperatures, the reactions proceed so quickly that enzymes are no longer helpful or required. 
B)  This is true of all catalysts and is not due to any special features of enzymes. 
C)  The kinetic energy of the reactants is so great that it destabilizes the enzyme and diminishes the enzyme's activity. 
D)  The kinetic energy of the reactants is lower than that of the products, forcing a change in enzyme activity. 
E)  The enzyme begins to denature above a certain temperature, eliminating all catalytic activity of the protein.

Question 19

Figure 6.4
Answer the question by using the accompanying graph. The optimal pH for enzyme 1 is ____.

Accepted Answer

A)  2 
B)  3 
C)  4 
D)  7 
E)  8 
A)  2 
B)  3 
C)  4 
D)  7 
E)  8

Question 20

What happens to an enzyme after it has catalyzed a reaction?

Accepted Answer

A)  It is sent to the proteasome for degradation. 
B)  It is inactivated by phosphorylation. 
C)  It is inactivated by dephosphorylation. 
D)  It releases the cofactor to get a new one ready for catalysis. 
E)  It returns to its original state. 
A)  It is sent to the proteasome for degradation. 
B)  It is inactivated by phosphorylation. 
C)  It is inactivated by dephosphorylation. 
D)  It releases the cofactor to get a new one ready for catalysis. 
E)  It returns to its original state.

Exam 6: Energy, Enzymes, and Biological Reactions

Why does the existence of ribozymes offer a possible solution to the question of whether nucleic acids or proteins appeared first in evolution?

If an enzyme is bound by an allosteric activator , the enzyme will convert from a low-affinity state to a high-affinity state.

Ribozymes are ____.

In order to prevent hair loss in men, one popular treatment is to use an inhibitor of the enzyme that converts testosterone to a different androgen (DHT). The inhibitors are steroids similar to testosterone that cannot be converted into DHT. How would you classify this type of inhibition?

ATP synthesis is exergonic .

Ribozymes are enzymes.

Answer the question using the accompanying graph. Which portion of the graph shows the free energy of the reaction?

According to the first law of thermodynamics, ____.

Enzymes ____.

The term that best describes all of the chemical reactions of a cell, including acquisition and use of molecules and energy, is ____.

Identify the exergonic reaction in the list below.

What is the significance of activation energy?

Energy from ATP is transferred to the reactant of an endergonic reaction by addition of a(n) _____ group to that molecule.

Zhang and Cech's experiments confirmed which feature of ribozyme activity?

In an exothermic reaction, ____.

Enzymes are ____ catalysts.

Which reaction is most likely to have more products than reactants when it reaches equilibrium?

Figure 6.3 In the accompanying figure, why does the curve sharply drop after approximately 45°C instead of mirroring the slope of the line going from 0-40°C?

Figure 6.4 Answer the question by using the accompanying graph. The optimal pH for enzyme 1 is ____.

What happens to an enzyme after it has catalyzed a reaction?

Introduction to Biological Concepts and Research

Life, Chemistry, and Water

Biological Molecules: the Carbon Compounds of Life

Cells

Membranes and Transport

Cellular Respiration: Harvesting Chemical Energy

Photosynthesis

Cell Communication

Cell Division and Mitosis

Meiosis: the Cellular Basis of Sexual Reproduction

Mendel, Genes, and Inheritance

Genes, Chromosomes, and Human Genetics

Dna Structure, Replication, and Organization

Gene Expression: From Dna to Protein

Regulation of Gene Expression

Bacterial and Viral Genetics

Dna Technology: Making and Using Genetically Altered Organisms, and Other Applications

Genomes and Proteomes

The Development of Evolutionary Thought

Microevolution: Genetic Changes Within Populations

Speciation

Paleobiology and Macroevolution

Systematic Biology: Phylogeny and Classification

The Origin of Life

Prokaryotes and Viruses

Protists

Seedless Plants

Seed Plants

Fungi

Animal Phylogeny, Acoelomates, and Protostomes

Deuterostomes: Vertebrates and Their Closest Relatives

The Plant Body

Transport in Plants

Plant Nutrition

Reproduction and Development in Flowering Plants

Plant Signals and Responses to the Environment

Introduction to Animal Organization and Physiology

Information Flow and the Neuron

Nervous Systems

Sensory Systems

The Endocrine System

Muscles, Bones, and Body Movements

The Circulatory System

Defenses Against Disease

Gas Exchange: the Respiratory System

Digestive Systems and Animal Nutrition

Regulating the Internal Environment: Osmoregulation, Excretion, and Thermoregulation

Animal Reproduction

Animal Development

Ecology and the Biosphere

Population Ecology

Population Interactions and Community Ecology

Ecosystems

Biodiversity and Conservation Biology

Animal Behavior

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