Unit 2 (Week 5 Assignment Questions) Flashcards
Reactions that release free energy are
exergonic.
spontaneous.
endergonic.
endothermic.
both a and b.
E
Enzymes speed up reactions by
providing chemical energy to fuel a reaction.
lowering the activation energy necessary to initiate a reaction.
causing an endergonic reaction to become an exergonic reaction.
substituting for one of the reactants necessary for a reaction.
none of the above.
B
For the idealized reaction aA + bB ⇌ cC + dD, suppose that the equilibrium constant, Keq, is 0.01. If the starting concentrations for A, B, C, and D are 1 M each, what would you predict based on the value of Keq?
The forward reaction is favored.
The reverse reaction is favored.
The forward reaction is fast.
The reverse reaction is fast.
both b and d.
B
IF the EC is over 1.0, the reaction is forward. Less than 1, the reaction is favored in reverse.
Researchers analyzed a cell extract—a mixture of molecules isolated from a certain type of cell—and studied a chemical reaction in which a carbohydrate was broken down into smaller molecules. When they added a protease to the cell extract, they discovered that the protease greatly inhibited the rate of the reaction. Based on this observation, you could conclude that the reaction is
exergonic.
endergonic.
catalyzed by an enzyme.
catalyzed by a ribozyme.
Both b and c are true of this reaction.
C
In biological systems, ATP functions by
providing the energy to drive endergonic reactions.
acting as an enzyme and lowering the activation energy of certain reactions.
adjusting the pH of intracellular solutions to maintain optimal conditions for enzyme activity.
regulating the speed at which endergonic reactions proceed.
interacting with enzymes as a cofactor to stimulate chemical reactions.
A
In a chemical reaction, NADH is converted to NAD+ + H+. We say that NADH has been
reduced.
phosphorylated.
oxidized.
decarboxylated.
methylated.
C
Scientists identify proteins that use ATP as an energy source by
determining whether a protein functions in anabolic or catabolic reactions.
determining if a protein has a known ATP-binding site.
predicting the free energy necessary for a protein to function.
determining if a protein has an ATP synthase subunit.
all of the above.
B
For a particular chemical reaction, an inhibitor raises the KM but does not affect the Vmax. This inhibitor
is a competitive inhibitor.
is a noncompetitive inhibitor.
binds to the active site of the enzyme.
binds to an allosteric site of the enzyme.
is a competitive inhibitor and binds to the active site of the enzyme.
E
Which of the following is (are) key benefits of catabolic reactions?
recycling of organic building blocks
breakdown of organic molecules to obtain energy
synthesis of important polymers, such as polypeptides
all of the above
a and b only
E
With regard to rate and direction, discuss the differences between endergonic and exergonic reactions.
Exergonic reactions are spontaneous. They proceed in a particular direction. An exergonic reaction could be slow or fast. By comparison, an endergonic reaction is not spontaneous. It will not proceed in a particular direction unless free energy is supplied. An endergonic reaction can be fast or slow.
Describe the mechanism and purpose of feedback inhibition in a metabolic pathway.
During feedback inhibition, the product of a metabolic pathway binds to an allosteric site on an enzyme that acts earlier in the pathway. The product inhibits this enzyme, thereby preventing the overaccumulation of the product.
A core concept of biology is that living organisms use energy. Explain why the recycling of amino acids and nucleotides is energy-efficient.
Recycling of amino acids and nucleotides conserves a great deal of energy. Cells don’t have to remake these building blocks, which would require a large amount of energy.
Which of the following can take place during a chemical reaction?
Multiple select question.
The amount of matter increases.
Molecules are broken apart.
Electrons are transferred between atoms.
Molecules attach to each other to form larger molecules.
Rearrangements of atoms within molecules occur.
B, C, D, E
What are the two main factors that determine the outcome of a chemical reaction in a living cell?
Multiple choice question.
Direction and rate
Reactants and products
Energy and reactants
Direction and rate
What is the term for the ability to do work?
Multiple choice question.
Kinetic energy
ATP
Energy
Potential energy
Energy
Energy that is associated with movement is termed ___________ energy, while _________ is stored energy.
Kinetic and potential
Which of the following statements are true according to the second law of thermodynamics?
Multiple select question.
As disorder increases, entropy increases.
Energy can be transferred or transformed from one form to another.
The transformation of energy from one form to another increases the entropy of a system.
Energy is conserved when transferred from one form to another.
As disorder increases, entropy increases.
The transformation of energy from one form to another increases the entropy of a system.
One or more substances are changed or converted into other substances during _____ reactions.
Chemical
For living organisms, the total energy (H) is called
_________, while the free energy (G) is the amount available to do work.
Enthalpy
A chemical reaction that will proceed without the input of energy is a(n) ________ reaction.
Exergonic or spontaneous
Which of the following describes the major difference between kinetic and potential energy?
Multiple choice question.
Kinetic energy is the energy of motion and potential energy is associated with the position of an object.
Potential energy is the energy of motion and kinetic energy is associated with the position of an object.
Kinetic energy is stored in chemical bonds and potential energy is associated with the position of an object.
A
What equation is used to evaluate whether a chemical reaction is spontaneous?
Multiple choice question.
ΔG = ΔH - TΔS
ΔG = ΔH + TΔS
ΔG = ΔH - TΔS
The delta indicates change, such as before and after a chemical reaction.
These statements pertain to the first law of thermodynamics. Which of them are true?
Multiple select question.
Energy is conserved when transferred from one form to another.
As disorder increases, entropy increases.
Energy can be transferred or transformed from one form to another.
The transformation of energy from one form to another increases the entropy of a system.
Energy is conserved when transferred from one form to another.
Energy can be transferred or transformed from one form to another.
What type of reaction results in products that contain less free energy than the reactants do?
Multiple select question.
exergonic reaction
spontaneous reaction
exothermic
passive
exergonic
endergonic
chemical
catabolic
anabolic
spontaneous
Exergonic reaction, spontaneous reaction, exergonic, spontaneous
When a water molecule is used to remove a phosphate group from ATP, this is called the __________ of ATP.
hydrolysis
What is enthalpy?
The total energy of a system
When does chemical equilibrium occur?
Multiple choice question.
When there is no enzyme available to catalyze a reaction
When the rate of formation of products equals the rate of formation of reactants
When no more reactants are available for the reaction
When a chemical reaction has gone to completion and the rate is zero
B
