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**Unformatted text preview: **Biophysical Chemistry Exam #5"
Hunter College, Spring 2016
Professor Massa 1) Why is the stoichiometric equation insufﬁcient for determining reaction rates? A. Stoichiometry provides theory but not the experimental component necessary for reaction rates. B. Stoichiometry provides the microscopic detail but not the broad overview of the reaction. C. The stoichiometric mechanism does not include the time dependence needed for reaction rates.
@ Many mechanisms can satisfy the stoichiometric equation. ~2) Which factors have the least impact on reaction rates?
. Catalysts.
Equilibrium constants
C. Enzymes.
D. Temperature. 3) What is generally false in regard to rate laws?
They may be determined by examining the stoichiometric equation.
. They may exhibit different orders as the reaction progresses.
C. They may be pseudo ﬁrst order.
D. They may be non-integral. 4) Reactions of which order exhibit a constant change in concentration with time?
A. First order. B. One-half order. C. Second order.
@ Zeroth order. 5) Which is true with regard to chemical kinetics and reaction rates? A. A ﬁrst order reaction must be ﬁrst order with respect to each of its reactants. B. A zeroth order reaction will have a constant concentration vs. time C. The test for zeroth order is to plot the log of the concentration vs. time.
@ A reaction that is second order overall may be first order with respect to each of its reactants. 6) Which is usually insufficient as a test for ﬁnding the order of a reaction?
A. Look for a straight line fit to the log of concentration vs. time.
Q) A visual examination of the concentration data vs. time.
C. Look for a straight line fit to concentration vs. time.
D. Look for a straight line ﬁt to the inverse concentration vs. time 7) What is true of a reaction that is overall second order given that rate = k[A][B]? A. Reaction rate decreases as the square as when the reactant concentrations double. B. Reaction rate increases as the square root when the reactant concentrations double.
@ Reaction rate quadruples when the reactant concentrations double. D. Reaction rate increases as the square when the reactant concentrations double. 8) For which plot depicted in k. the rate determining step?
tat >< K
\ i 9) For the generalized plot depicted in the figure. what can be said about E. vs. EM? A. The k, and k; values are apparently equal in both cases. .
B. It is not possible to tell from a visual examination. 0. The graph on the top ® The graph on the bottom A. E. is greater in the reverse reaction.
E. is greater in the forward reaction.
. E. is lesser in the forward reaction.
D. E. and EM are equal in the forward and reverse reactions. |N I” m m
Mo“ 10) Which photochemical effect has the clearest hazards to biological systems?
® UV light of sufﬁcient energy to create genetic mutations.
B. Cis to trans conversion of retinal in the delicate eye photoreceptors.
C. Light that generates ozone in our atmosphere.
D. Photochemistry to produce a chemical mix of radicals. charged species and neutrals of different oxygen.
nitrogen and hydrogen compounds. 11) Which is the optimal method for extracting Vm and Km from enzyme conversion data?
A. Prepare an Eadie-Hofstee plot.
B. Prepare a Dixon plot.
C. Prepare a Lineweaver—Burk plot.
® Prepare a direct least-squares fit to the experimental rate data as a function of [S]. 12) Why are graphical methods still essential to understanding enzyme kinetics?
A. They are the only method to acquire Km.
B. Their current primary utility is as teaching aids. They are the only method to acquire me. .
They relate measured concentrations under different important extrema to direct human interpretation. 13) Why is the uncatalyzed breakdown of H202 so slow?
A. Due to the activation energy of the reverse reaction
(3 Due to the activation energy of the forward reaction
. Due to the rapid reverse reaction that replenishes H20, nearly as rapidly as it is broken down
D. Due to the fact that the H20, breakdown reaction is a three-body problem 14) What is the turnover number as relates to the maximum kinetic reaction rate in enzyme kinetics?
Q The rate divided by the concentration of enzyme sites '. The rate divided by the number of enzymes C. The rate divided by the concentration of substrates D. The rate divided by the normalized concentration of substrates 15) Which is NOT known to act as an enzyme?
A Ribonucleic acid molecules
Deoxyﬁbonucieic acids
. Proteins
D. Metallic groups 16) Which of these guarantees that for a quantum mechanical calculation, the probability of ﬁnding an electron in all space will be 100 percent?
A. The calculation of the average position of the electron
B. Electron energy distribution
Normalization
. The calculation of the time-dependent orbital shape 17) Which is an invalid boundary condition for a wavefunction? Q? The wave function should have symmetric potential.
. The wavefunction of a bound electron should vanish at inﬁnite distance.
C. The wavefunction should be continuous both as a function and for the ﬁrst derivative, except where at a boundary.
D. The wave function should be single-valued and ﬁnite. 18) For a particle in a box, how would the emission wavelength from n = 5 to n = 4 compare to the emission
from n = 4 to n = 3?
A. This transition is absorption, not emission. B. It would be longer.
@ It wouid be shorter.
D. It would be the same wavelength. 19) Of the choices below, what is the most general solution of the time-independent Schrodinger equation?
A Asin(kx)
Asin(kx)+Bcos(kx)
. Ae-kx+Bekx
D. Bcos(kx) 20) The Wavefunction W of a particle is in general
A. a real quantity. 3 complex quantity. . not differentiable. D. none of the above. 21) For a particle in a one-dimensional box the ground state energy is obtained for n = 0,where the integer n,
is a quantum number. " ' ~ : True.
6 False. 22) For a particle in a three-dimensional particle in a box the wave function W can be written, by the method
of separation of variables, as a sum of three functions, X, Y and 2 each of which depends on only one of the coordinates. ‘ True.
False. 23) A particle is conﬁned to a one-dimensional box on the x-axis between x = O and x =L. The potential height
of the walls of the box is inﬁnite. The normalized wave function of the particle, which is in the ground state, is
given by W(x) = x/(ZI L) sin rrxl L, 0 5x SL. The probability of finding the particle between x = 0 and x =U2, is
closest to: A 0.20 0.33
0.50
. 0.62 E. 0.80 24) How does the probability of an electron tunneling through a potential barrier vary with the thickness of the
barrier" A It decreases with decreasing thickness.
.It decreases with increasing thickness. C. It increases with increasing thickness. D. It is independent of the barrier thickness. 25) Particles in a box with ﬁnite potential energy walls have no probability of being outside the box.
A True. @alse. ...

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