Question 1

How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction?

Accepted Answer

A)  by binding to the active site of the enzyme, thus preventing binding of the normal substrate 
B)  by binding to an allosteric site, thus changing the shape of the active site of the enzyme 
C)  by decreasing the free-energy change of the reaction catalyzed by the enzyme 
D)  by binding to the substrate, thus changing its shape so that it no longer binds to the active site of the enzyme 
A)  by binding to the active site of the enzyme, thus preventing binding of the normal substrate 
B)  by binding to an allosteric site, thus changing the shape of the active site of the enzyme 
C)  by decreasing the free-energy change of the reaction catalyzed by the enzyme 
D)  by binding to the substrate, thus changing its shape so that it no longer binds to the active site of the enzyme

Question 2

Biological systems use free energy based on empirical data that all organisms require a constant energy input. The first law of thermodynamics states that energy can be neither created nor destroyed. For living organisms, which of the following statements is an important consequence of this first law?

Accepted Answer

A)  The energy content of an organism is constant except for when its cells are dividing. 
B)  The organism must ultimately obtain all the necessary energy for life from its environment. 
C)  The entropy of an organism decreases with time as the organism grows in complexity. 
D)  Organisms are unable to transform energy from the different states in which it can exist. 
A)  The energy content of an organism is constant except for when its cells are dividing. 
B)  The organism must ultimately obtain all the necessary energy for life from its environment. 
C)  The entropy of an organism decreases with time as the organism grows in complexity. 
D)  Organisms are unable to transform energy from the different states in which it can exist.

Question 3

Which of the following statements is consistent with the second law of thermodynamics?

Accepted Answer

A)  A gain of free energy in a system is always associated with conversion of energy from one form to another. 
B)  A constant input of energy is required to maintain the high level of cellular organization. 
C)  Without an input of energy, the entropy of an organism would tend to decrease over time. 
D)  Every energy transformation performed by an organism decreases the entropy of the universe. 
A)  A gain of free energy in a system is always associated with conversion of energy from one form to another. 
B)  A constant input of energy is required to maintain the high level of cellular organization. 
C)  Without an input of energy, the entropy of an organism would tend to decrease over time. 
D)  Every energy transformation performed by an organism decreases the entropy of the universe.

Question 4

Use the following information to answer the question below.
 
Activity of various enzymes at various temperatures (a) and at various pH (b)
Which temperature and pH profile curves on the graphs are most likely associated with an enzyme isolated from a human stomach where conditions are strongly acid?

Accepted Answer

A)  curves 1 and 4 
B)  curves 1 and 5 
C)  curves 2 and 4 
D)  curves 3 and 4 
A)  curves 1 and 4 
B)  curves 1 and 5 
C)  curves 2 and 4 
D)  curves 3 and 4

Question 5

Rate of an enzyme-catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme constant.
For the enzyme-catalyzed reaction shown in the figure, if the initial reactant concentration is 1.0 micromolar, which of these treatments will cause the greatest increase in the rate of the reaction?

Accepted Answer

A)  doubling the activation energy needed 
B)  cooling the reaction by 10°C 
C)  doubling the enzyme concentration 
D)  increasing the concentration of reactants to 10.0 micromolar, while reducing the concentration of enzyme by 1/2 
A)  doubling the activation energy needed 
B)  cooling the reaction by 10°C 
C)  doubling the enzyme concentration 
D)  increasing the concentration of reactants to 10.0 micromolar, while reducing the concentration of enzyme by 1/2

Question 6

The mathematical expression for the change in free energy of a system is ΔG = ΔH - TΔS. Which of the following statements is correct?

Accepted Answer

A)  ΔS is the change in enthalpy, a measure of randomness. 
B)  ΔH is the change in entropy, the energy available to do work. 
C)  ΔG is the change in free energy. 
D)  T is the temperature in degrees Celsius. 
A)  ΔS is the change in enthalpy, a measure of randomness. 
B)  ΔH is the change in entropy, the energy available to do work. 
C)  ΔG is the change in free energy. 
D)  T is the temperature in degrees Celsius.

Question 7

Which of the following statements describes a key component of the induced fit hypothesis of enzyme catalysis?

Accepted Answer

A)  Substrate binds to an allosteric site rather than to the active site of an enzyme. 
B)  Binding of an activator molecule changes the shape of the active site of an enzyme. 
C)  The conformation of the active site is determined by the tertiary or quaternary structure of the enzyme. 
D)  Binding of substrate to the active site changes the shape of the active site of an enzyme. 
A)  Substrate binds to an allosteric site rather than to the active site of an enzyme. 
B)  Binding of an activator molecule changes the shape of the active site of an enzyme. 
C)  The conformation of the active site is determined by the tertiary or quaternary structure of the enzyme. 
D)  Binding of substrate to the active site changes the shape of the active site of an enzyme.

Exam 8: An Introduction to Metabolism

How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction?

Which of the following statements is consistent with the second law of thermodynamics?

Use the following information to answer the question below. Activity of various enzymes at various temperatures (a) and at various pH (b) Which temperature and pH profile curves on the graphs are most likely associated with an enzyme isolated from a human stomach where conditions are strongly acid?

The mathematical expression for the change in free energy of a system is ΔG = ΔH - TΔS. Which of the following statements is correct?

Which of the following statements describes a key component of the induced fit hypothesis of enzyme catalysis?

Evolution, the Themes of Biology, and Scientific Inquiry

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Viruses

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Vascular Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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