Question 1

Enthalpy (H) is the ________.

Accepted Answer

A)  total kinetic energy of a system 
B)  total energy in biological systems 
C)  system's entropy 
D)  cell's energy equilibrium 
E)  condition of a cell that is not able to react 
A)  total kinetic energy of a system 
B)  total energy in biological systems 
C)  system's entropy 
D)  cell's energy equilibrium 
E)  condition of a cell that is not able to react B

Question 2

-You have discovered an enzyme that can catalyze two different chemical reactions. Which of the following is most likely to be correct?

Accepted Answer

A)  The enzyme contains α-helices and β-pleated sheets. 
B)  The enzyme is subject to competitive inhibition and allosteric regulation. 
C)  Two types of allosteric regulation occur: The binding of one molecule activates the enzyme, while the binding of a different molecule inhibits it. 
D)  Either the enzyme has two distinct active sites or the reactants involved in the two reactions are very similar in size and shape. 
A)  The enzyme contains α-helices and β-pleated sheets. 
B)  The enzyme is subject to competitive inhibition and allosteric regulation. 
C)  Two types of allosteric regulation occur: The binding of one molecule activates the enzyme, while the binding of a different molecule inhibits it. 
D)  Either the enzyme has two distinct active sites or the reactants involved in the two reactions are very similar in size and shape. D

Question 3

Use the following information to answer the question(s) below.
A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.
-Some bacteria are metabolically active in hot springs because ________.

Accepted Answer

A)  they are able to maintain a lower internal temperature 
B)  high temperatures make catalysis unnecessary 
C)  their enzymes have high optimal temperatures 
D)  their enzymes are completely insensitive to temperature 
E)  they use molecules other than proteins or RNAs as their main catalysts 
A)  they are able to maintain a lower internal temperature 
B)  high temperatures make catalysis unnecessary 
C)  their enzymes have high optimal temperatures 
D)  their enzymes are completely insensitive to temperature 
E)  they use molecules other than proteins or RNAs as their main catalysts C

Question 4

A chemical reaction that has a positive ΔG is best described as ________.

Accepted Answer

A)  endergonic 
B)  entropic 
C)  enthalpic 
D)  spontaneous 
E)  exergonic 
A)  endergonic 
B)  entropic 
C)  enthalpic 
D)  spontaneous 
E)  exergonic

Question 5

Which of the following is TRUE of enzymes?

Accepted Answer

A)  Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered. 
B)  Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. 
C)  Enzymes increase the rate of chemical reaction by lowering activation energy barriers. 
D)  Enzymes increase the rate of chemical reaction by providing activation energy to the substrate. 
A)  Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered. 
B)  Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. 
C)  Enzymes increase the rate of chemical reaction by lowering activation energy barriers. 
D)  Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.

Question 6

-Consider the HIV enzyme called protease. The amino acid residues at the active site are highly hydrophobic. In designing a drug that would bind to the active site and jam it, researchers should use a molecule that is ________.

Accepted Answer

A)  hydrophobic 
B)  polar 
C)  charged 
D)  acidic 
A)  hydrophobic 
B)  polar 
C)  charged 
D)  acidic

Question 7

Which of the following is an example of potential rather than kinetic energy?

Accepted Answer

A)  the muscle contractions of a person mowing grass 
B)  water rushing over Niagara Falls 
C)  light flashes emitted by a firefly 
D)  a molecule of glucose 
E)  a crawling beetle foraging for food 
A)  the muscle contractions of a person mowing grass 
B)  water rushing over Niagara Falls 
C)  light flashes emitted by a firefly 
D)  a molecule of glucose 
E)  a crawling beetle foraging for food

Question 8

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction?

Accepted Answer

A)  -40 kcal/mol 
B)  -20 kcal/mol 
C)  0 kcal/mol 
D)  +20 kcal/mol 
E)  +40 kcal/mol 
A)  -40 kcal/mol 
B)  -20 kcal/mol 
C)  0 kcal/mol 
D)  +20 kcal/mol 
E)  +40 kcal/mol

Question 9

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure.  
-Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C + D → A + B, in the figure?

Accepted Answer

A)  a 
B)  b 
C)  c 
D)  d 
E)  e 
A)  a 
B)  b 
C)  c 
D)  d 
E)  e

Question 10

Why is ATP an important molecule in metabolism?

Accepted Answer

A)  Its hydrolysis provides an input of free energy for exergonic reactions. 
B)  It provides energy coupling between exergonic and endergonic reactions. 
C)  Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. 
D)  Its terminal phosphate bond has higher energy than the other two phosphate bonds. 
E)  It is one of the four building blocks for DNA synthesis. 
A)  Its hydrolysis provides an input of free energy for exergonic reactions. 
B)  It provides energy coupling between exergonic and endergonic reactions. 
C)  Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. 
D)  Its terminal phosphate bond has higher energy than the other two phosphate bonds. 
E)  It is one of the four building blocks for DNA synthesis.

Question 11

Use the following information to answer the question(s) below.
A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.
-With respect to the enzyme that converts X to Y, substance A functions as ________.

Accepted Answer

A)  a coenzyme 
B)  an allosteric inhibitor 
C)  the substrate 
D)  an intermediate 
E)  a competitive inhibitor 
A)  a coenzyme 
B)  an allosteric inhibitor 
C)  the substrate 
D)  an intermediate 
E)  a competitive inhibitor

Question 12

To attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur for the final attachment to occur?

Accepted Answer

A)  The ATP must first have to attach to the tRNA. 
B)  The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme. 
C)  The ATP must be hydrolyzed to allow the amino acid to bind to the synthetase. 
D)  The tRNA molecule must alter its shape to be able to fit into the active site with the other two molecules. 
E)  The 3' end of the tRNA must be cleaved before it can have an attached amino acid. 
A)  The ATP must first have to attach to the tRNA. 
B)  The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme. 
C)  The ATP must be hydrolyzed to allow the amino acid to bind to the synthetase. 
D)  The tRNA molecule must alter its shape to be able to fit into the active site with the other two molecules. 
E)  The 3' end of the tRNA must be cleaved before it can have an attached amino acid.

Question 13

According to the induced fit hypothesis of enzyme catalysis, ________.

Accepted Answer

A)  the binding of the substrate depends on the shape of the active site 
B)  some enzymes change their structure when activators bind to the enzyme 
C)  a competitive inhibitor can outcompete the substrate for the active site 
D)  the binding of the substrate changes the shape of the enzyme's active site 
E)  the active site creates a microenvironment ideal for the reaction 
A)  the binding of the substrate depends on the shape of the active site 
B)  some enzymes change their structure when activators bind to the enzyme 
C)  a competitive inhibitor can outcompete the substrate for the active site 
D)  the binding of the substrate changes the shape of the enzyme's active site 
E)  the active site creates a microenvironment ideal for the reaction

Question 14

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

Accepted Answer

A)  the need for a coenzyme 
B)  allosteric inhibition 
C)  competitive inhibition 
D)  insufficient cofactors 
A)  the need for a coenzyme 
B)  allosteric inhibition 
C)  competitive inhibition 
D)  insufficient cofactors

Question 15

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as ________.

Accepted Answer

A)  metabolic inhibition 
B)  feedback inhibition 
C)  allosteric inhibition 
D)  noncooperative inhibition 
E)  reversible inhibition 
A)  metabolic inhibition 
B)  feedback inhibition 
C)  allosteric inhibition 
D)  noncooperative inhibition 
E)  reversible inhibition

Question 16

You collect data on the effect of pH on the function of the enzyme catalase in human cells. Which of the following graphs would you expect?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
A) 
  
B) 
  
C) 
  
D)

Question 17

Which of the following statements is a logical consequence of the second law of thermodynamics?

Accepted Answer

A)  If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe. 
B)  If there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe. 
C)  Every energy transfer requires activation energy from the environment. 
D)  Every chemical reaction must increase the total entropy of the universe. 
E)  Energy can be transferred or transformed, but it cannot be created or destroyed. 
A)  If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe. 
B)  If there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe. 
C)  Every energy transfer requires activation energy from the environment. 
D)  Every chemical reaction must increase the total entropy of the universe. 
E)  Energy can be transferred or transformed, but it cannot be created or destroyed.

Question 18

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure.  
-HIV is the virus that causes AIDS. In the mid-1990s, researchers discovered an enzyme in HIV called protease. Once the enzyme's structure was known, researchers began looking for drugs that would fit into the active site and block it. If this strategy for stopping HIV infections were successful, it would be an example of what phenomenon?

Accepted Answer

A)  vaccination 
B)  denaturation 
C)  allosteric regulation 
D)  competitive inhibition 
A)  vaccination 
B)  denaturation 
C)  allosteric regulation 
D)  competitive inhibition

Question 19

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________.

Accepted Answer

A)  exergonic; spontaneous 
B)  exergonic; endergonic 
C)  free energy; entropy 
D)  work; energy 
E)  entropy; enthalpy 
A)  exergonic; spontaneous 
B)  exergonic; endergonic 
C)  free energy; entropy 
D)  work; energy 
E)  entropy; enthalpy

Question 20

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure.  
-Which of the following terms best describes the forward reaction in the figure?

Accepted Answer

A)  endergonic, ∆G > 0 
B)  exergonic, ∆G  0 
E)  chemical equilibrium, ∆G = 0 
A)  endergonic, ∆G > 0 
B)  exergonic, ∆G  0 
E)  chemical equilibrium, ∆G = 0

Exam 8: Energy and Enzymes: an Introduction to Metabolism

Enthalpy (H) is the ________.

-You have discovered an enzyme that can catalyze two different chemical reactions. Which of the following is most likely to be correct?

A chemical reaction that has a positive ΔG is best described as ________.

Which of the following is TRUE of enzymes?

-Consider the HIV enzyme called protease. The amino acid residues at the active site are highly hydrophobic. In designing a drug that would bind to the active site and jam it, researchers should use a molecule that is ________.

Which of the following is an example of potential rather than kinetic energy?

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction?

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure. -Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C + D → A + B, in the figure?

Why is ATP an important molecule in metabolism?

According to the induced fit hypothesis of enzyme catalysis, ________.

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as ________.

You collect data on the effect of pH on the function of the enzyme catalase in human cells. Which of the following graphs would you expect?

Which of the following statements is a logical consequence of the second law of thermodynamics?

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________.

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure. -Which of the following terms best describes the forward reaction in the figure?

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

Protein Structure and Function

Nucleic Acids and the Rna World

An Introduction to Carbohydrates

Ecosystems and Global Ecology

Lipids, Membranes, and the First Cells

Inside the Cell

Cellular Respiration and Fermentation

Photosynthesis

Cellcell Interactions

The Cell Cycle

Meiosis

Mendel and the Gene

Dna and the Gene: Synthesis and Repair

How Genes Work

Transcription, Rna Processing, and Translation

Control of Gene Expression in Bacteria

Control of Gene Expression in Eukaryotes

The Molecular Revolution: Biotechnology and Beyond

Genes, Development, and Evolution

Evolution by Natural Selection

Evolutionary Processes

Speciation

Phylogenies and the History of Life

Bacteria and Archaea

Protists

Green Algae and Land Plants

Fungi

An Introduction to Animals

Protostome Animals

Deuterostome Animals

Viruses

Plant Form and Function

Water and Sugar Transport in Plants

Plant Nutrition

Plant Sensory Systems, Signals, and Responses

Plant Reproduction and Development

Animal Form and Function

Water and Electrolyte Balance in Animals

Animal Nutrition

Gas Exchange and Circulation

Animal Nervous Systems

Animal Sensory Systems

Animal Movement

Chemical Signals in Animals

Animal Reproduction and Development

The Immune System in Animals

An Introduction to Ecology

Behavioral Ecology

Population Ecology

Community Ecology

Biodiversity and Conservation Biology

Filters

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as is to .