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122 Cards in this Set

  • Front
  • Back
Which of the following statement(s) about biochemical pathways is (are) TRUE?
a. they are very well organized and structured.
b. they convert an initial substrate via a series of steps into an end product.
c. they can only function for a few runs.
d. A and B
e. A, B, and C
d. A and B
Consider the biochemical pathway: A - E1--> B - E2--> C
Enzyme 1 can utilize:
a. only A as substrate
b. only B as substrate
c. both A and B as substrates
d. neither A nor B as substrate
e. either A or B as substrate, but not both.
a. only A as substrate
Consider the biochemical pathway: A – E1 –> B – E2 –> C
If Enzyme 2 is inactive, which of the following compounds will accumulate?
a. A only
b. B only
c. C only
d. A and B
e. B and C
b. B only
True/False
In a biochemical pathway, the product of the first reaction becomes the substrate in the second reaction.
True
True/False All biochemical pathways have the same number of enzymatic reactions.
False
Which of the following is the most comprehensive definition of "energy"?
a. the ability to make high-energy compounds.
b. the capacity to do work.
c. changes in the amount of heat in a system.
d. potential power.
b.
How does a catalyst assist a chemical reaction?
a. it allows the reaction to release more energy upon completion.
b. it adds more energy to the reactant so it can achieve an unstable state, thus exceeding the activation energy demand.
c. it provides an alternative method for the reaction to occur which is more energetically favorable than would occur without the catalyst.
d. it converts a nonspontaneous (endergonic) reaction to a spontaneous one (exergonic).
e. it allows the second law of thermodynamics to be reversed.
c.
True/False
ATP is a nucleotide
False
Which of the following is MOST likely to affect the effeciancy (activity) of an enzymatic reaction?
a. Changes in temperature.
b. Feedback Inhibition.
c. Absence of cofactors such as metal ions in the active site.
d. All of the above affect enzyme activity
e. None of the above affect enzyme activity.
d.
How might a membrane improve the efficiency of an enzymatic pathway?
a. It creates order in what is otherwise a highly disordered cytoplasm.
b. it can orient active sites of enzymes in the same pathway towards a chamber containing the reactants.
c. it increases the amount of entropy in the reaction, giving the overall reaction and more negative ΔG value.
d. it decreases the activation energy of all the enzymatic catalysts by an equal amount.
d.
Enzymes are
a. lipids
b. proteins
c. carbohydrates
d. nucleic acids
d. steroids
b.
Which of the following binds to the active site of an enzyme?
a. water
b. product
c. substrate
d. any other enzyme
e. none of the above
b. pr
c.
Which of the following correctly represents the mechanism of enzyme function?
a. S + P --> E-P --> E + P
b. E + P --> E-P--> E-S--> E+S
c. E + P --> E-S--> E-P--> E + P
d. E + S --> E-S --> E-P --> E + P
e. E + S --> E-P -->E-S --> E+S
d.
True/False
An enzyme can only bind one reactant at a time.
False
True/False
An enzyme speeds up a chemical reaction in the cell, but can only be used once.
False
In simple terms sucrase
a. joins glucose and fructose together to form sucrose
b. breaks sucrose into glucose and fructose
c. forms a dissacharide from a monosaccharide
d. breaks sucrose into hydrogen, oxygen and carbon atoms
b.
How does sucrose change the configuration of sucrase?
a. by significant trauma when they collide randomly.
b. by changing the pH of the solvent.
c. by force when under pressure.
d. by binding to the active site.
d.
How does the energy of sunlight enter into biological systems?
a. it increases the kinetic energy of the molecules it contacts.
b. it oxidizes organic molecules in a redox reactio.
c. it allows the conversion of simple molecules into complex ones.
d. it breaks the bonds between carbon and hydrogen.
e. it is converted from potential to kinetic energy during photosynthesis
c.
During an endergonic reaction
a. disorder of the individual molecules of the reaction is increased.
b. the amount of entropy in a system is decreased
c. the ΔG of the overall reaction is negative.
d. all of the above occurs.
e. none of the above occurs.
b.
The formation of ATP from ADP and phosphate is analogous to
a. Breakind down glucose to get its energy.
b. Climbing stairs up a slide then going down it
c. The flowing of water from the top of a waterfall to a pool below.
d. The priming of a mouse trap by fastening the trap wire after tightening its spring.
e. Absorption of sunlight by a plant pigment.
d.
The active site of an enzyme which breaks down fatty acids is most likely
a. dominated by polar amino acid side chains (R groups)
b. Hydrophobic
c. Rich in nonpolar covalent bonds found in hydrocarbons.
d. Rich in acidic R-groups
e. Rich in basic R-groups
c.
Why does the activity of an enzyme decline assymetrically from the optimal pH on either side, rather than showing a rapid decline as temperature increases from the optimum?
a. hydrogen bonds, which are most susceptible to heat, pull apart suddenly but the covalent bonds in disulfide linkages are broken down during pH changes in either direction.
b. enzymes work best at around 40 degrees C but are evolutionarily turned to function at a variety of pH levels.
c. only heat can denature an enzyme.
d. The acids and bases hydrolyze the amino acids at the same time.
e. Ionization changes in acid R-groups on one side of the optimum are offset about equally for those changes in basic R-groups on the other side, disrupting ionic stabilization of the tertiary structure.
e.
In feedback inhibition, the inhibitor of the biochemical pathway is typically
a. the substrate of the enzyme inhibited.
b. the product of the enzyme inhibited.
c. a substance that is produced towards the middle of the biochemical pathway.
d. the final product of the biochemical pathway.
e. a product of another biochemical pathway.
d.
What does the inhibitor bind to during feedback inhibition?
a. active site of the enzyme being inhibited.
b. allosteric site of enzyme being inhibited.
b.
Consider the biochemical pathway used to synthesize the amino acid proline. A high increase in the level of proline will most likely lead to
a. a decrease in proline production.
b. a further increase in proline production.
c. no change in the rate of proline production.
d. increased breakdown of proline.
e. proline being converted to praline.
a.
True/False If the end product of a biochemical pathway becomes available in the environment it is crucial for the cell to continue making the product.
False
True/False A biochemical pathway consists of a specific sequence of enzyme-catalyzed reactions.
True
A covalent bond between two atoms represents what kind of energy?
a. kinetic energy
b. potential energy
c. mechanical energy
d. solar energy
b.
During a redox reaction the molecule that gains an electron has been--
a. reduced and now has a higher energy level
b. oxidized and now has a lower energy level
c. reduced and now has a lower energy level
d. oxidized and now has a higher energy level
a.
An endergonic reaction has the following properties--
a. +ΔG and the reaction is spontaneous
b. +ΔG and the reaction is not spontaneous
c. -ΔG and the reaction is spontaneous
d. -ΔG and the reaction is not spontaneous
b.
A spontaneous reaction is one in which--
a. the reactants have a higher free energy than the products
b. the products have a higher free energy than the reactants
c. energy is required
d. entropy is decreased.
a.
What is activation energy?
a. the thermal energy associated with random movements of molecules.
b. the energy released through the active breaking of chemical bonds.
c. the difference in free energy between reactants and products.
d. the energy required to initiate a chemical reaction
d.
Which of the following is NOT a property of a catalyst?
a. a catalyst reduces the activation energy of a reaction. b. a catalyst lowers the free energy of the reactants.
c. a catalyst does not change as the result of the reaction.
d. a catalyst works in both forward and reverse directions of a reaction.
b.
Where is the energy stored in a molecule of ATP?
a. Within the bonds between nitrogen and carbon.
b. In the carbon bonds found in the ribose.
c. In the oxygen double bound.
d. in the bonds connecting the two terminal phosphate groups
d.
Why is ATP capable of driving endergonic reactions?
a. Because ATP is a catalyst.
b. Energy released by ATP makes the ∆G for coupled reactions more negative
c. Energy released by ATP makes the ∆G for coupled reactions more positive
d. Because the conversion of ATP to ADP is also endergonic.
b.
Which of the following statements is NOT true about enzymes?
a. Enzymes use the 3-D shape of their active site to bind reactants.
b. enzymes lower the activation energy for a reaction
c. the process of the reactions alters the enzyme
d. Enzymes can catalyze the forward and reverse directions of a reaction.
c.
What is the function of the active site of an enzyme?
a. It binds to the substrate, forming an enzyme-substrate complex.
b. Side groups within the active site interact with the substrate
c. It binds to the product, triggering induced fit of the protein.
d. both A and B
d.
A multienzyme complex is capable of--
a. catalyzing a single reaction at a much greater rate
b. catalyzing a series of reactions using multiple different enzymes
c. lowering the activation energy for a reaction through the activity of multiple enzymes.
d. both a and c
b.
What is the common factor that influences enzyme function at extreme temperatures or pH?
a. the rate of movement of the substrate molecules
b. the strength of the chemical bonds within the substrate
c. the three dimensional shape of the enzyme
d. the rate of movement of the enzyme
c.
The discovery of ribozymes meant that--
a. only proteins have catalytic function.
b. only nucleic acids have catalytic function
c. some RNAs have enzymatic activity
d. RNA could be destroyed by enzymes
c.
Molecules that bind within the active site of an enzyme are ________, whereas molecules that bind at a site distant from the active site are ___________.
competitive inhibitors, allosteric inhibitors
In glycolysis, a glucose in converted to
a. CO2 and H2O
b. pyruvate
c. citrate
d. acetyl-CoA
e. NAD+ and ADP.
b.
The NET result of a single glycolysis run is the formation of how many NADH and ATP?
2 NADH and 2 ATP
Under anaerobic conditions, the end-product of glycolysis is converted to
a. amino acids
b. lactic acid
c. hydrochloric acid
d. acetic acid
c.
True/False During glycolysis, a 6-carbon sugar disphosphate molecule is split into two 3-carbon sugar phosphate molecule.
True
Under aerobic conditions, the end-product of glycolysis is further REDUCED to yield more ATP.
False- oxidized
Cells obtain energy by ________ food molecules such as glucose.
a. reducing
b. oxidizing
c. redoxing
d. anabolizing
e. phosphorylating
b.
A hydrogen atom consists of
protons and electrons
True/False Whenever a molecule is oxidized, another molecule must be reduced.
True
True/False NADH serves an electron carrie that can donate its hydrogen to other molecules.
True
Before entering the Krebs cycle, pyruvate is converted to
a. glucose
b. acetic acid
c. acetyl-CoA
d. oxaloacetate
c.
A single "turn" of the Krebs cycle will yield
__ ATP, ___NADH, __FADH2
1 ATP
3 NADH
1 FADH2
The initial reaction of the Krebs cycle involves the addition of a
a. 2 carbon molecule to a 4 carbon molecule
b. 2 carbon molecule to a 5 carbon molecule
c. 2 carbon molecule to a 6 carbon molecule
d. 3 carbon molecule to a 4 carbon molecule
e. 3 carbon molecule to a 5 carbon molecule
a.
True/False The Krebs cycle occurs in the mitochondrion.
True
True/False A single "turn" of the Krebs cycle involves four different decarboxylation reactions.
False-two
Arrange the following electron acceptors in the proper order in which they participate in electron transport.
1=cytochrome c
2=oxygen
3=cytochrome c oxidase
a. 1,2,3
b. 1,3,2
c. 2,3,1
d. 3,1,2
e. 3,2,1
b.
The electrons that are transferred through the electron transport system initially belonged to
a. NADH
b. FADH2
c. ATP
d. oxygen
e. NADH and FADH2
e.
The movement of protons through ATP synthase occurs from the
a. matrix to the intermembrane space
b. matrix to the cytoplasm
c. intermembrane space to the matrix
d. intermembrane space to the cytoplasm
e. cytoplasm to the intermembrane space
c.
True/False When oxygen accepts electrons, water is produced as a byproduct.
True
True/False The formation of True/False ATP as a result of the activity of the electron transport system is termed substrate-level phosphorylation.
False
The electron transport chain in bacteria is located
a. in the cytoplasm
b. in the mitochondria
c. in the cell wall
d. in the cell membrane
e. in the plasmid
d.
During aerobic respiration, the last carrier protein transfers a pair of electrons to
a. water
b. NADH
c. Oxygen
d. coenzyme Q.
e. a proton (H+)
c.
The function of the enzyme ATP synthase is to
a. accept a proton from the inside of the cell membrane as it accepts electrons
b. utilize the energy of the proton motive force to convert ADP to ATP.
c. produce reduced coenzymes like NADH
d. transfer hydrogen to the electron transport chain
e. shuttle electrons from NADH to a terminal electron acceptor
b.
True/False Electrons enter the electron transport chain when NADH transfers them there along with protons in the form of hydrogen.
True
True/False The electron transport chain consists of a series of membrane-bound carriers that shuttle protons and electrons to NADH.
False- Oxygen
Which is the best definition for cellular respiration?
a. the use of oxygen in a cell.
b. the oxidation of organic compounds to extract energy from chemical bonds.
c. production of ATP in a cell
d. respiration of cells to get energy to survive
e. reduction of NADH to drive chemical reactions in a cell.
b.
True/False
Because it has 6 carbons, glucose can power 6 cycles ("turns") of the Krebs cycle.
False- 2 turns
Which of the following statements is false?
a. some ATP is consumed in glycolysis
b. glycolysis releases two pyruvate and two CO2 molecules
c. Some ATP is created through substrate-level phosphorylation
d. Overall, glycolysis releases energy and is thus termed exergonic.
e. All of the above statements are true
b.
Where in a eukaryotic cell does pyruvate oxidation occur?
a. in the mitochondrion.
b. in the electron transport chain.
c. in the cytoplasm, just like in prokaryotes
d. anywhere in the cell, provided pyruvate dehydrogenase is present
e. two of the above are locations where pyruvate oxidation occurs
c.
True/False
The Krebs cycle is responsible for making most of the cell's ATP.
False
Which of the following is most directly responsible for creation of ATP at the mitochondrial inner membrane?
a. vast quantities of NADH.
b. a proton gradient
c. a lot of FADH2 in the cell
d. movement of electrons along the membrane itself
e. the activity of NADH hydrogenase
b.
Why is it misleading to say "when completely oxidized, each glucose molecule results in the production of 36 ATP molecules"?
a. because of the efficiency of chemiosmosis, the result is actually much higher.
b. FADH2 actually consumes some ATP.
c. The cell membrane is someowhat leaky to H+ ions.
d. the proton gradient can facilitate other tasks besides ATP synthesis
e. You had to add in ATP produced during glycolysis, which has nothing to do with oxidation.
d.
Which of the following serve as control points to regulate the rate of glucose catabolism?
a. Phosphofructokinase and pyruvate dehydrogenase
b. The electron transport chain
c. all of the above.
a.
True/False The purpose of fermentation is to make ethanol.
False- ethanol and lactic acid
What process must occur to allow amino acids to be catabolized for energy?
a. deamination
b. depurination
c. dephosphorylation
d. dehydration
e. deoxygenation
a.
Primitive prokaryotes probably used H2S instead of water as a source of electrons. What would have been released into the environment as photosynthesis occured?
a. gaseous hydrogen
b. liquid hydrogen
c. water
d. HS
e. sulfur
e.
Why does NAD+ serve as an important electron carrier?
a. it is readily reduced and oxidized.
b. it is insoluble and is stationary within the cell
c. it can accept electrons in a variety of positions along its length
d. it "protects" electrons from winding up in fatty acid precursors where the energy would be wasted.
e. all of the above are correct.
a.
What products result from the complete oxidation of glucose?
a. CO2
b. ATP
c. NADH
d. FADH2
e. all of these result from glucose oxidation
e.
Why must NAD+ be present during glycolysis?
a. it creates pyruvate directly from glucose.
b. a glycolysis intermediate must be oxidized in order to receive a phosphate so that substrate-level phosphorylation may occur.
c. it powers the electron transport chain.
d. it is a coenzyme which allows the 6 carbons of glucose to separate from each other.
e. This is a trick question: NAD+ is only involved in the Krebs cycle
b.
What is/are the product(s) of pyruvate oxidation?
a. O2
b. Acetyl-CoA
c. NAD+
d. ATP
e. all of the above are created during pyruvate oxidation
b.
How many CO2 molecules are released specifically from the Krebs cycle for each glucose molecule consumed?
a. 1
b. 2
c. 3
d. 4
e. 5
d.
Suppose the catalytic heads of ATP synthase are all enzymatically removed (say, by cutting the stalk which holds it to the rotor). What consequence is most logical?
a. Negative feedback will be decreased, causing faster ATP production.
b. The electron transport chain will slow down.
c. The cell will have no mechanism to make ATP and will die.
d. Protons will quickly equilibrate between the matrix and intermediate space
e. all of the above will occur
d.
For one molecule of glucose, what is the maximum number of ATP molecules created directly from the Kreb's cycle?
a. 1
b. 2
c. 3
d. 4
e. 5
b.
What is the name of the mechanism by which pyruvate dehydrogenase is inhibited by the end poduct of the biochemical pathway?
a. anabolism
b. catabolism
c. regulation
d. negative inhibition
e. regurgitation
d.
When yeast ferment a product, they create CO2, but animal cells do not. What is the difference in their fermentation strategies?
a. Yeast prefer to make ethanol.
b. Ethanol has two carbons, while lactate has three.
c. Yeast get more energy when they ferment than do animals
d. Animals have a central nervous system, which allows for bette metabolic decisions
e. Yeast are protists, and do things differently than more-evolved creatures such as animals
a.
Some diet regimens claim to operate by excluding some chemicals from the food consumed. People who abstain from eating certain foods don't simply run out of energy and die. Choose the most plausible answer for why they don't.
a. They create all the enzymes they need after ingesting food.
b. Macromolecules have an inherent property of stimulating the enzymes required for their degradation for energy.
c. Oxidation pathways of food molecules are interrelated to such an extent that enzymes can link their breakdown from different starting points.
d. Life is so intentive and versatile that natural selection can take over and bind organic pathways to allow the organism to survive.
e. The genetic information in an organism are so complex that it's possible to create new enzymes when required.
c.
Which of the following argues most strongly for glycolysis as one of the most primitive biochemical pathway?
a. It does not require oxygen in order to function.
b. It occurs in the cytoplasm of cells
c. It is exergonic, and therefore obeys the laws of thermodynamis which are fundamental to chemistry and physics.
d. the amino acid sequence for enzymes of this pathway are almost identical in all living creatures
e. There is no evidence that glycolysis is primitive
d.
An autotroph is an organism that--
a. extracts energy from organic sources
b. converts energy from sunlight into chemical energy
c. relies on the energy produced by other organisms as an energy source
d. both a and b
d.
Which of the following processes is (are) required for the complete oxidation of glucose?
a. The Krebs cycle
b. Glycolysis
c. Pyruvate oxidation
d. All of the above
d.
The energy associated with a molecule of glucose is stored in its--
a. carbon atoms
b. chemical bonds
c. electrons
d. protons
b.
How is ATP produced by glycolysis?
a. Through the priming reactions
b. Through the production of glyceraldehyde-3-phosphate
c. By substrate-level phosphorylation
d. As a result of the reduction of NAD+ to NADH
c.
Which of the following is NOT a true statement regarding cellular respiration?
a. Enzymes catalyze reactions that transfer electrons
b. Electrons have a higher potential energy at the end of the process
c. Carbon dioxide is a byproduct
d. The process involves multiple redox reactions
b.
An autotroph is an organism that--
a. extracts energy from organic sources
b. converts energy from sunlight into chemical energy
c. relies on the energy produced by other organisms as an energy source
d. both a and b
d.
Which of the following processes is (are) required for the complete oxidation of glucose?
a. The Krebs cycle
b. Glycolysis
c. Pyruvate oxidation
d. All of the above
d.
The energy associated with a molecule of glucose is stored in its--
a. carbon atoms
b. chemical bonds
c. electrons
d. protons
b.
How is ATP produced by glycolysis?
a. Through the priming reactions
b. Through the production of glyceraldehyde-3-phosphate
c. By substrate-level phosphorylation
d. As a result of the reduction of NAD+ to NADH
c.
Which of the following is NOT a true statement regarding cellular respiration?
a. Enzymes catalyze reactions that transfer electrons
b. Electrons have a higher potential energy at the end of the process
c. Carbon dioxide is a byproduct
d. The process involves multiple redox reactions
b.
The majority of the ATP produced during aerobic respiration is made by--
a. the electrons carried by NADH
b. the movement of hydrogen ions through an ATP synthase enzyme
c. substrate-level phosphorylation
d. autophosphorylation
b.
What is the role of NAD+ in the process of cellular respiration?
a. It functions as an electron carrier.
b. It functions as an enzyme.
c. It is the final electron acceptor for anaerobic respiration
d. It is a nucleotide source for the synthesis of ATP.
a.
Which of the following is NOT a product of glycolysis?
a. ATP
b. Pyruvate
c. CO2
d. NADH
c.
Why is fermentation an important metabolic function in cells?
a. It generates glucose for the cell in the absence of O2.
b. It oxidizes NADH to NAD+
c. It oxidizes pyruvate
d. It produces ATP
b.
Which of the following statements is NOT true about the oxidation of pyruvate?
a. Pyruvate oxidation occurs in the cytoplasm.
b. Pyruvate oxidation only occurs if oxygen is present.
c. Pyruvate is converted into acetyl-CoA
d. Pyruvate oxidation results in the production of NADH.
a.
The Krebs cycle occurs in which region of a mitochondrion?
a. the inner membrane
b. the intermembrane space
c. the outer membrane
d. the matrix
d.
What happens to the electrons carried by NADH and FADH2?
a. they are pumped into the intermembrane space
b. they are transferred to the ATP synthase
c. they are moved between proteins in the inner membrane of the mitochondrion.
d. they are transported into the matrix of the mitochondrion.
c.
Can cellular respiration occur in the absence of O2?
a. No, O2 is required as the final electron acceptor.
b. No, anaerobic organisms only need glycolysis and fermentation
c. Yes, because oxygen can be generated by splitting H2O.
d. Yes, but only when another final electron acceptor is available.
d.
Catabolism of fatty acids results in the production of--
a. pyruvate
b. glucose
c. acetyl-CoA
d. citrate
c.
What evidence supports the idea that glycolysis evolved early in the history of life?
a. Glucose is a simple molecule
b. The reaction of glycolysis is common to all living things
c. Glycolysis requires few steps compared with other reactions
d. all of the above
b.
High levels of NADH will inhibit what enzyme in aerobic respiration?
Pyruvate dehydrogenase
High levels of ATP in aerobic respiration inhibit what enzyme in aerobic respiration?
Citrate synthetase
What enzyme can be inhibited by high levels of ATP and activated by high levels of ADP?
Phosphofructokinase
How can proteins be catabolized to enter the Krebs cycle or glycolysis?
Through deamination and transamination
What is the difference between deamination and transamination?
Deamination is the removal of an amino group and transamination is the transferring of an amino group to another molecule
What happens to the amino group when it undergoes transamination?
It is converted to urea through the urea cycle and is transported to urine
How are fats catabolized to acetyl groups?
Through Beta-oxidation to move onto the Krebs cycle
True/False The respiration of a 6-carbon fatty acid yields 30% more energy than glucose
False 20%
Acetyl CoA gives __ ATP through beta-oxidation
14
ATP can use what acid to convert fatty acids to adipose tissue?
pyruvic acid
Methanogens make use anaerobic respiration by using what molecule and converting it the CH4 which is what?
CO2
CH4 is methane
Which of the following reactions shows anaerobic respiration through nitrate reduction?
a. NO4- + 2e- + 2H+ --> NO3- + H2O
b. NO2- + 2e- + 2H+ --> NO3- + H2O
c. NO3- + 2e- + 2H+ --> NO2- + H2O
d. NO2- + 2e- + 2H+ -->NO4- + H2O
c.
In anaerobic respiration by sulfur bacteria, inorganic sulfate (SO4) is reduced to what?
Hydrogen sulfide (H2S)
In alcohol fermentation in yeast, 2 pyruvates each give off a carbon dioxide and create 2 _____________, which is reduce by NADH to 2 ethanol.
acetaldehyde
In lactic acid fermentation in muscle cells, electrons are transferred from 2 NADH to 2 pyruvate to produce 2 ______ ____ molecules.
lactic acid