1) All the following are true about enzymes except
A. Enzymes can speed up the rate of spontaneous reactions.
B. Enzymes are often involved in endergonic reactions.
C. Enzymes are the most common type of catalysts in leaving organisms
D. Enzymes are consumed during chemical reactions
2) Enzymes increase the rate of chemical reactions by
A. Making endergonic reactions proceed spontaneously
B. Reducing the initial amount of energy required for the reaction to proceed
C. Increasing the entropy of the reactions
D. Increasing the amount of substrate
3) The place where substrates bind to enzymes is referred to as the
A. Active side
B. Enzyme-substrate complex
C. Transition area
D. Allosteric site (a site on an enzyme where a molecule can bind noncovalently
and affect the function of the active site)
4) Which of the following statements is TRUE
A. An enzyme with high Km will have a low affinity for a substrate
B. An enzyme with high Km will have a high affinity for a substrate
C. An enzyme with high Km will have low Vmax
D. An enzyme with high Km will have a high Vmax
5) How can the effect of a competitive inhibitor be overcome?
A. By increasing the concentration of the enzyme
B. By decreasing the concentration in cofactors
C. By increasing the concentration of the substrate
D. By decreasing the affinity an enzyme has for its substrate
6) What is Vmax?
A. The point at which an enzyme is saturated with substrate
B. The point at which the velocity of a reaction is half its maximal value
C. The point at which the affinity of an enzyme for its substrate is equal to the
substrate concentration
D. The point at which substrate concentration is large enough to cause
Conformational change in an enzyme
7) Which of the following statements is TRUE
A. The ability of enzyme to catalogue a reaction can be affected by pH
B. All cofactors are also coenzymes
C. Enzyme affinity is always positively related to temperature
D. Coenzymes are altered after binding to enzyme.
8) Noncompetitive inhibitors bind to an enzyme’s active site to cause a confrontational
change in enzyme structure
A. True
B. False
9) Which of the following would you predict to be TRUE of the fatty acyl tails of the
phospholipids in a bacterium which live best at very high temperatures
A. Long fatty acid tails
B. Short fatty acid tails
C. Unsaturated fatty acid tails
D. B and C
10) What would you predict to happen if you removed cholesterol from the membrane of
human cell?
A. The membrane would solidify
B. Nothing, cholesterol is not important for membrane structure and function
C. The membrane will become too fluid, resulting in leakiness
D. Nothing, human cells do not normally contain cholesterol
11.Glycolipids and Glycoproteins located in the plasma membrane may serve as
A. Ion channels
B. Recognition signals
C. ATP-driven pumps
D. Transporters
12. Most membrane phospholipids are synthesized
A. At the cytosolic leaflet of the smooth ER membrane
B. At the nuclear envelope
C. vesicles
D. In chloroplast and mitochondria
13. Given an artificial membrane composed only of phospholipids which of
the following would you expect to cross readily?
A. Glucose
B.O2
C. Insulin
D. Na+
14.An electro chemical gradient of H+ across membrane involves
which of the following
A. A change in gradient
B. A gradient of hydrogen ions
C. A gradient of pH
D. All of the above
15. What is the major difference between passive diffusion and facilitated diffusion?
A. Involvement of a transport protein
B. Direction of solute movement
C. Expenditure of energy
D. Movement of solute vs. movement of water.
16. When bacteria use H+/sucrose symporter __________ are moving down their
concentration gradient, while __________ are moving up their concentration gradient
A. Sucrose molecules, H+ ions
B. H+ ions, sucrose molecules
C. H+ ions, ATP
D.ATP, sucrose molecules
17. What is the major difference between active transport and passive transport
C. Whether the solute is hydrophilic or hydrophobic
D. Whether a channel or a transporter is used
E. Whether water or solute is moving across a membrane
D. Energy requirement
18. Trans membrane gradients involving ions have
A. An electrical component
B. A chemical component
C. Both an electrical and chemical component
D. Neither electrical nor chemical component
19. Glycolysis provides ATP by which of the following
A.ATP synthase
B. Substrate- level phosphorylation
C. Electrochemical gradient
D. Oxidative phosphorylation
E. Reduction of CoA
20. What substance is produced by the oxidation of pyruvate and feeds into the citric acid
cycle
A. Carbon dioxide
B.NADH
C.FAD
D. Acetyl-CoA
21. The citric acid cycle starts and ends with the four carbon molecule
A. Oxaloacetate
B. Lactate
C. Citrate
D. Ethanol
D. Pyruvate
22. During what stage of cellular respiration is the most ATP synthesized
A. Citric cycle
B. Oxidation of pyruvate
C. Glycolysis
D. Oxidative phosphorylation
23. Glycolysis occurs in the -------and citric acid cycle in the ----------A. cytosol, inner mitochondria membrane.
B. mitochondrial matrix, inner mitochondria membrane.
C. cytosol, mitochondria matrix.
D. outer mitochondria membrane, inner mitochondria membrane.
24. Which of the following is an example of cellular respiration?
A. breakdown of glucose.
B. breakdown of fats.
C. breakdown of proteins
D. all of the above
25. Why is the maximal amount of ATP that can be made by oxidative
phosphorylation rarely achieved?
A. Excess CO2 produced by the citric acid cycle degrades some ATP.
B. Some NADPH and FADH are used for anabolic pathways.
C. Mitochondria may use some of the H+ electrochemical gradient for
Other purposes.
D. Some NADPH is quickly broken-down to NAD+ when exposed to light.
E. B & C are correct.
1. When the cytoplasm of a cell is hypotonic to its environment:
a) osmosis will cause the cell to lyse
b) osmosis will cause the cell to crenate (shrivel)
c) the solute concentration is greater inside the cell
d) there is no net water movement
e) the membrane potential will become more negative
2. Which is NOT true about the fluid mosaic model?
a) membrane proteins are embedded in the membrane
b) membrane phospholipids are in a liquid state
c) membrane proteins can laterally diffuse
d) some organisms change fatty acid composition with temperature changes
e) membrane protein composition is similar in different cell types
3. Facilitated diffusion transport
a) requires membrane proteins
b) requires ATP hydrolysis
c) requires H+ cotransport
d) requires membrane potential
e) requires osmosis
4. The Na+, K+ pump
a) transports Na+ by its electrochemical gradient
b) transports K+ out of the cell
c) does not require an energy output
d) is regulated by phosphorylation-dephosphorylation
e) is an example of facilitated diffusion
5. Active transport depending on ATP hydrolysis
a) transfers the chemical bond energy of hydrolysis as heat
b) requires fluidity of the membrane lipid bilayer
c) transports ions along their electrochemical gradient
d) has a constant binding affinity for transported ions
e) is not a form of allosteric regulation
6. Cells control their metabolism by
a) inhibitors
b) activators
c) enzymes
d) substrates
e) products
7. When the cytoplasm of a cell is hypertonic to its environment
a) osmosis will cause the cell to lyse
b) osmosis will cause the cell to crenate
c) the solute concentration is greater inside the cell
d) there is no net water movement
e) the membrane potential will become more negative
8. Which of the following statements is true about facilitated diffusion?
a) It depends on the total concentration of all molecules
b) It requires an expenditure of energy by the cell
c) It is a passive process in which molecules move from a region of higher concentration to a
region of lower concentration
d) It is an active process in which molecules move from a region of lower concentration to one
of higher concentration
e) It does not require a channel or carrier protein in the cell membrane
9. Which is true about the fluid mosaic model?
a) Membrane proteins are only attached to the membrane surfaces
b) Membrane phospholipids are in a solid state
c) Membrane proteins are equally distributed throughout the membrane
d) Membrane proteins can penetrate across the lipid bilayer
e) Membrane phospholipids readily flip-flop between leaflets
10. What is/are used by biological systems as energy coupler(s) between catabolism and anabolism?
a) NADPH
b) ATP
c) oxygen
d) A & B
e) B & C
11. The Na+, K+ pump does NOT
a) transport Na+ out of the cell
b) transport K+ into the cell
c) require ATP hydrolysis
d) change its conformation and ion affinity
e) transport equal amounts of Na+ & K+ per cycle
12. A reaction is considered to be spontaneous when
a) it violates the 1st law of thermodynamics
b) it violates the 2nd law of thermodynamics
c) it is anabolic
d) Delta G is less than 0
e) Delta G is greater than 0
13. The 2nd law of thermodynamics requires all reactions
a) to convert one form of energy to another
b) to be endergonic
c) to increase the level of entropy in the universe
d) to decrease the disorder in the universe
e) to always be respectful towards energy
14. Competitive inhibitors of enzyme activity bind at the
a) regulatory site
b) cooperativity site
c) active site
d) allosteric site
e) none of the above
15. Enzyme-substrate binding at the active site is called induced fit because
a) they act as lock-and-key
b) initial weak bond interactions change the active site confirmation for further binding and
catalysis
c) it is like OJ Simpson trying on shrunken gloves
d) catalysis is not initiated by weak bond interactions in the active site
e) active site binding changes allosteric regulation of the enzyme
16. Why doesn’t a spontaneous reaction occur?
a) Delta G of a reaction is less than zero
b) Delta G of a reaction is greater than zero
c) Delta G of a reaction is zero
d) Activation energy is a barrier
e) none of the above
17. Why is the rate of reaction increased by enzyme catalysis?
a) The activation energy barrier is reduced
b) The substrates remain the same
c) The products remain the same
d) B & C
e) A & B
18. If an enzyme is inhibited noncompetitively,
a) the Delta G for the reaction will always be negative
b) the inhibitor may be chemically unrelated to the substrate
d) the active site will be irreversibly occupied by the inhibitor
d) raising the substrate concentration will increase inhibition
e) more energy will be necessary to initiate the reaction
19. If more enzyme is added to a solution where its substrate and product are in equilibreium, what
would happen?
a) Additional product will be formed
b) Additional substrate will be formed
c) The reaction switched from exergonic to endergonic
d) Nothing, the reaction would stay at equilibrium
e) The change in free energy of the reaction would increase
20. Which of the following is NOT associated with allosteric regulation of an enzyme’s activity?
a) A mimic of the substrate competes for the active site
b) An activator stabilizes a catalytically active conformation
c) Regulatory molecules bind at a site separate from the active site
d) Inhibitors and activators may compete with each other for binding
e) The enzyme has quaternary structure
21. The diffusion of an ion is NOT dependent on
a) its chemical concentration gradient
b) the phospholipid content in the membrane
c) the cell membrane potential
d) the presence of channel proteins in the membrane
e) the concentrations of other ions
22. Which statement is true about cotransport?
a) It is a passive transport mechanism
b) It utilizes an ion electrochemical gradient
c) It is not necessary for transport of sugars against their chemical concentration gradient
d) It requires phosphorylation of the transport protein
e) none of the above
23. Which statement is true about osmosis?
a) occurs from higher solute concentration to lower solute concentration
b) depends only on permeant solute concentrations
c) depends only on impermeant solute concentrations
d) requires ATP hydrolysis
e) occurs from lower solute concentration to higher solute concentration
24. What is the effect of an enzyme on a reaction?
a) changes the reactants
b) changes the products
c) changes the free energy difference
d) changes the activation energy barrier
e) changes the allosteric regulation
25. Which of the following statements correctly describes any chemical reaction that has reached
equilibrium?
a) The concentration of products equals the concentration of reactants
b) The rate of the forward reaction equals the rate of the reverse reaction
c) Both the forward and reverse reactions have halted
d) There is no longer any reactants to fuel the reaction
e) The reaction is no longer reversible
26. Which of the following statements about the 5’ end of a nucleic acid is correct?
a) The 5’ end has a phosphate group
b) The 5’ end has a hydroxyl group
c) The 5’ end has a carbonyl group
d) The 5’ end is identical to the 3’ end
e) The 5’ end is the 5th position on one of the nitrogenous bases
27. Which of the following pairs of base sequences could form a short stretch of a normal double helix
of DNA?
a) 5’-A-G-C-T-A-C-3’ & 5’-A-G-C-T-A-C-3’
b) 5’-A-G-C-T-A-C-3’ & 5’-C-A-T-C-G-A-3’
c) 5’-A-G-C-T-A-C-3’ & 5’-G-T-A-G-C-T-3’
d) 5’-A-G-C-T-A-C-3’ & 5’-T-C-G-A-T-G-3’
e) none of the above
28.