Chapter 8
Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
catabolism
A chemical reaction that has a +ΔG. is correctly describes as
Endergonic
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
It is lost to the environment.
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. What is substance X?
substrate
Which of the following is a statement of the first law of thermodynamics
Energy cannot be created or destroyed
Which of the following best describes enthalpy(H)
The heat content of a chemical system
How can one increase the rate of a chemical reaction
add a catalyst
Which of the following is considered an open system?
an organism
How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?
by changing the shape of a reactant
Catabolism is to animalism as
Exergonic is to endergonic
When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows:
+ΔG, +ΔH, -ΔS.
Which shows the correct changes in thermodynamic properties for a chemical reaction in which amino acid's are links to form a protein
+ΔG, -ΔS, +ΔH
During a laboratory experiment, you discover that an enzyme catalyzed reaction has a ΔG of -20 kcal/mole. If you double the amount of enzyme in the reaction, what will be the ΔG for the new reaction
-20 kcal/mole
Which of the following statements describes enzyme cooperativity
A substrate molecule bound to an active site affects the active site of several subunits
Reactants capable of interchanging to form products in a chemical reaction must first overcome a thermal dynamics barrier known as the reactions
Activation energy
Living organisms increasing complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?
As a consequence of growing, organisms create more disorder in their environment then the decrease in entropy associated with their growth
Which statement is representative of the second law of thermodynamics
Cells require a constant input of energy to maintain their high level of organization.
When you have a severe fever, what may be a grave consequences if this is not controlled
Change in the folding of enzymes
Besides turning enzymes on or off, what other means doesn't cell use to control enzymatic activity
Compartmentalization of enzymes into defined organelles
Which of the following metabolic processes can occur without a net influx of energy from some other process
C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O
The mathematical expression for the change in free energy of a system is delta G equals delta H minus T delta S. Which of the following is correct?
Delta G is change in free energy
What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways
Energy coupling
Which of the following statements regarding enzymes is true
Enzymes increase the rate of a reaction
Which of the following is true of enzymes
Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
Which of the following statements is a logical consequence of the second law of thermodynamics
Every chemical reaction must increase the total entropy of the universe.
When ATP release some energy, it also releases inorganic phosphate. What purpose does that serve in the cell?
It can be added to other molecules in order to activate them
Why is ATP an important molecule in metabolism?
It provides energy coupling between exergonic and endergonic reactions.
Which of the following is true of metabolism in its entirety
Metabolism is a property of organismal life
If an enzyme is added to a solution with substrate and product are in equilibrium, what would occur
Nothing
Which of the following is most similar in structure to ATP
RNA nucleotide
When 10,000 molecules of ATP are hydrolyzed to ADP and Pi in a test tube, about twice as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation?
Reactant and product concentrations are not the same
According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
The binding of the substrate changes the shape of the enzyme's active site.
For a living organisms, which of the following is an important consequence of the first law of thermodynamics
The organism ultimately must obtain all of the necessary energy for life from its environment.
Which of the following statements is true about enzyme catalyzed reactions
The reaction is faster than the same reaction in the absence of the enzyme.
Which of the following is true for all Exergonic reactions
The reaction proceeds with a net release of free energy.
Assume that the reaction has a ΔG of -5.6 kcal/mole. Which of the following would be true?
The reaction would result in an increase in entropy(S) and a Decrease in the total energy content (H) of the system.
What must be the difference between the structure of ATP in the structure of the precursor of the A nucleotide in DNA and RNA
There is no difference
Which of the following statements is true concerning catabolic pathways
They are usually coupled with anabolic pathways to which they supply energy in the form of ATP.
Which of the following is true about anabolic pathways
They consume energy to build up polymers from monomers
Chemical equilibrium is relatively rare in living cells which of the following could be an example of a reaction a chemical equilibrium in the cell
a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway
Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n)
a cofactor necessary for enzyme activity
Which of the following is an example of potential rather than Kinetic Energy?
a food molecule made up of energy-rich macromolecules
Which of the following is an example of cooperativity
a molecule binding at one unit of a tetramer, allowing faster binding at each of the other three
If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to
add more of the enzyme
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. Substance A functions as
an allosteric inhibitor
Some enzymatic regulation is allosteric. In such cases, which of the following would usually be found?
an enzyme with more than one subunit
Which of the following is likely to lead to an increase in the concentration of ATP in a cell
an increase in a cell's catabolic activity
Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in
breaking the bond between glucose and fructose and forming new bonds from the atoms of water.
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following
competitive inhibition
Which Of the following types of reactions would decrease the entropy within a cell
dehydration reactions
Whenever energy is transformed, there is always an increase in the
entropy of the universe
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as
feedback inhibition
The organization of organisms has become increasingly complex with time. This statement
is consistent with the second law of thermodynamics
The active site of an enzyme is the region that
is involved in the catalytic reaction of the enzyme
What is the change in free energy of a system at chemical equilibrium
no net change
Most cells cannot harness heat to perform work because
temperature is usually uniform throughout a cell
Competitive inhibitors block the entry of a substrate Into the active site of an enzyme. On which of the following properties of an active site does this primarily depend
the ability of an enzyme to form a template for holding and joining molecules
A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because
the activation energy barrier for this reaction cannot be surmounted.
Among enzymes, kinases catalyze phosphorylation, while phosphatases catalyze removal of phosphate(s). A cell's use of these enzymes can therefore function as an on-off switch for various processes. Which of the following is probably involved?
the change in a protein's charge leading to a conformational change.
Some bacteria are metabolically active in hot springs because
their enzymes have high optimal temperatures
