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AAMC Chemical and Physical Foundations Biological Systems Questions with Correct Answers.
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AAMC Chemical and Physical Foundations Biological Systems Questions with Correct Answers.
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AAMC Chemical and Physical Foundations BiologicalSystems Questions with Correct Answers
What is the mechanical work done by the cantilever when the extension
increases from 10 nm to 15 nm?
2.00 × 10-22 J
4.70 × 10-20 J
2.50 × 10-19 J
5.00 × 10-18 J Correct Answer-This question requires you to apply the
graphical method of calculating the work done by a variable force,
namely the elastic force, W = ksx2/2. Mechanical work by an elastic
force is W = ksx2/2 = Fx/2. Graphically, it is the area under the force-
extension graph between the corresponding data points. From Figure 2,
the correct response is {[(100 - 0) × 10-12]N ×[(15 - 10) × 10-9]m}/2 =
2.50 × 10-19 J.
What are the units for the rate constant ku discussed in the passage?
M-1•s-1
M•s
M•s-1
s-1 Correct Answer-The protein unfolds by a unimolecular mechanism.
The rate of unfolding has units of M/s and is given by the expression
Δ[unfolded protein length]/Δt = ku[folded protein length]. The units of
ku are therefore s-1.
,What modification of Compound 1 will favor transport of Na+ relative
to K+?
Replace X with CH3.
Replace Y with CH3.
Increase the ring size by adding one -CH2CH2O-.
Decrease the ring size by removing one -CH2CH2O-. Correct Answer-
From the passage, it was stated that K+ is transported within the central
portion of Compound 1. Since Na+ is chemically similar to K+ it is
reasonable to assume that there might be a way to favor its transport
over K+ by changing the size of the ring. The change necessary would
be to decrease the ring size since Na+ is smaller than K+.
A compound has 5 chiral centers. How many possible stereoisomers
does it have? Correct Answer-32. 2^n
Why do kidney stones form in some individuals treated with Compound
1?
A.[Ca2+] + [C2O42-] > Ksp
B.[Ca2+][C2O42-] > Ksp
C.[Ca2+] + [C2O42-] < Ksp
D.[Ca2+][C2O42-] < Ksp Correct Answer-B. Precipitates occur when
concentrations exceed Ksp (solubility product constant)
,In the membrane of an axon in respect to its extracellular environment,
which direction would electric field lines be drawn? Correct Answer-
Pointing from extracellular fluid to the inside of the axon membrane.
Electric field lines exit from positive and enter negative charges. The
axon is negatively charged. The extracellular solution has a zero net
potential.
Channel X transmits only the smallest substances dissolved in the
extracellular fluid through the axon membrane. Which substance does
Channel X transmit?
A.Proteins
B.Sodium ions
C.Potassium ions
D.Chloride ions Correct Answer-The answer to this question is B
because sodium cations are the smallest of the species listed. You can
use the periodic table to establish that sodium ions are smaller than
either potassium or chloride ions
A nerve impulse lasts about 1ms. If the signal is conducted at 100 m/s,
What is the closest distance the electrodes used in an NCV test can be
placed on a nerve in order to measure the voltage change as a response
to the stimulus?
A.0.01 m
B.0.1 m
C.1.0 m
, D.10 m Correct Answer-The answer to this question is B because the
shortest time duration that can be detected is not less than the action
potential time response of 1 msec, according to Figure 1. The distance
travelled by the impulse during this time is 1 msec × 100 m/s = 0.1 m,
which is the closest distance the electrodes must be placed on the nerve.
What information about an axon is required to calculate the current
associated with an NCV pulse?
A.Conductivity, resistivity, and length
B.Potential, conductivity, and radius
C.Potential, resistivity, and radius
D.Potential, resistance per unit length, and length Correct Answer-The
answer to this question is D. This is a question about Ohm's Law, I =
V/R. To determine R, the resistance per unit length, the length, and the
potential V are needed.
The hydrogen ion concentration of the unknown aqueous solution was 1
× 10-5 M.
What was the pH of the unknown aqueous solution?
A.4
B.5
C.9
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