Missed Chem and Physics Questions
Kaplan FL4 Q58. In the reaction below, the carbanion acts as:
a strong Bronsted base. (exp. it accepts 2 hydrogens so it is a bronsted base. CaOH in the reaction is a strong base, and the reaction is proceeding forward. CaOH is a product, but if it is still going forward then carbanion must be stronger.)
Kaplan FL5 Q3. A combustion engine in a production plant is in contact with a coil of pipes carrrying water that functions to cool the engine. The water is converted to steam and flows through a long vertical pipe to be released into the atmosphere. Heat is transferred from the engine to the atmosphere primarily by:
conduction, then convection.
As an alternative to Experiment 2, the chemist also can improve the yield of the polymer obtained in Experiment 1 by increasing the amount of:
CDP (substrate). This is due to Le Chat principle. Increasing enzyme wouldn't increase product, just the rate.
Which of the following compounds is expected to be the most acidic?
CH3OH2+ (this molecule is eager to deprotonate and that is why it is a stronger acid)
Kaplan FL4 Q14. The electrons that give color to a carotene molecule are found in:
pi orbitals. The paragraph 2 talks about conjugated double bonds and that wavelength of absorbbed light increases with the number of double bonds.
Kaplan FL5 Q50. Which of the following CANNOT be the rate law for the production of AA metabolites?
rate = k[arachidonic acid][cyclooxygenase] (exp. Arachidonic acid is the rate determinng step.)
Kaplan FL4 Q52. In order to be transported form the skin to the liver via the bloodstream, vitamin D3 must:
travel throught he circualtory system attached to a vitamin D-binding protein. (Exp. vitamin D is fat soluble so it needs something to carry it through the aqueous blood)
Kaplan FL5 Q14. The stereogenic center created in Step 4 predominantly exists in only one configuration because in order to create the stereogenic center with the opposite configuration:
The reaction would have to proceed through a more strained transition state.
Kaplan FL5 Q54. The biophysical model described in the passage assumes that the lipid bilayer acts like a parallel plate capacitor with a fixed capacitance. Which of the following is NOT an assumption made by the model?
The resistivity of the axon's cytoplasm is 2.0 ohms/meter (exp. the resistivity of the axoplasm is irrelevant to the capacitive ability of the lipid bilayer, since the axoplasm is outside (not betwee) the two layers that make up the lipid bilayer and form parallel plates in the model)
Kaplan FL4 Q30. A student performs a titration with a base as the itrant and an acid as the analyte. He finds that the pH at the equivalenc point is 8.3, and concludes that he was adding NaOH to HF. Which of the following observations made during the titration does NOT support his conclusion?
To reach the equivalence point, 10 mL of base (0.5M) was added to 5mL of acid (0.25M). (Exp. it would take 20mL of acid (0.25M) to neutralize the base.
Kaplan FL26. Based on the Venturi effect, if a kidney stone is partially blocking one ureter, how are the velocity and hydrostatic pressure of urine affected as it passes through the point of the blockage?
Velocity increases and hydrostatic pressure decreases. (Exp. velocity increases to maintain continuity and hydrostatic pressure decreases to conserve mechanical energy)
Kaplan FL4. Q A scientist measures the rate of phosphatidic acid production in stock solutions containing physiologic concentrations of glycer-3-phosphate, ATP, fatty acids, and CoA. His enzye assay includes numerous trials in which he varies the concentrations of acyl-CoA transferase and acyl-CoA synthetase. The results from this study would most help answer which of the following questions.
Which enzyme is physiologically saturated at a lower concentration?
Kaplan FL4 Q57. Which of the following statements about NAD is true?
NAD is composed of two nucleotides joined by their phosphate groups.
Kaplan FL4 Q33. A typical MRI system used in a hospital has a magnetic field strength between 1.5 and 5 T, while a refrigerator magnet has a strength of 5 mT. Which of the following is NOT equivalent to 1 T?
1(C x s)/(kg) (Exp. F=qvB, B=F/qv)
Kaplan FL5 Q52. A capacitor containing two flat, parallel plates separated by a vacuum is connected to a battery with voltage V. While still connected to the battery, its plates arepulled apart to a distance double the original one. By what factor does the energy density between the plates change?
1/4 (exp. E = V/d and u = 1/2 eE^2)
Kaplan FL4 Q34. Although MRI relies on signals from hydrogen because of its abundance in the body, other elements can be imaged with MRI. Which of the follwoing are most likely to be good candidates for MRI imagine?
13C and 31P (Exp. Needs to have a magnetic momentum to interact in a magnetic field. Odd number of protons and neutrons would allow this.)
Kaplan FL5 Q42. What is the root mean square speed of an As4 particle as it is sublimed? (assume at high temperatures arsenic acts like an ideal gas; the Boltzmann constant, kB, can be approximated as 1.4 x 10^-23 J/K) and the kinetic energy of the gas is equal to 3/2kB T.
270 m/s (exp. 3/2kB T = 1/2 mv^2)
Kaplan FL5 Q24. The researcher wants to construct a shielding apparatus for a laboratory facility that experiments with 50 keV X-rays. What is the minimum thickness for a lead shield that could reasonably be considered safe?
3.1 mm (see explanation in test)
Kaplan FL5 Q33. In an exhibition, the fastest recorded pitcher was playing against a batter 60 feet from the pitching mound. If the ball was thrown horizontally and took 0.4 seconds to reach home plate, what was its vertical velocity as it passed over home plate?
4 m/s (exp. (10 m/s^2)(0.4 m/s))
Kaplan FL5 Q32. Assume that the human arm has a mass of 4.5 kg in a baseball player, and that it is distributed half in the hand, half in the shoulder. If the length from the shoulder to the hand is 0.8 m, the tension exerted by the arm as it reaches maximal velocity is most nearly:
40 kN. (exp. F=mv^2/r. Half the weight is in the hand so the mass is 2.25 kg, r is 0.8m. To find velocity you must find the distance using the circumference equation C=2(pi)r= 2(3.14)(0.8) ~5. Then you take 24 revolutions at 5 meters per second and get 120 m/s. F = (2.25)(120)^2/0.8 = 40,000 N.)
Kaplan FL5 Q46. The isoelectric points of glycine and lysine are 6.0 and 9.6, respectively. These amino acids can be separated by electrophoresis at a pH of:
6.0 or 9.6
Kaplan FL4, Q1. Based on the information in the passage, how many molecules of NADH would be produced by the complete B-oxidation of stearic acid, which has 18 carbons, into acetyl-CoA? Ignore any further production of NADH by other metabolic pathways.
8. It undergoes 8 rounds of Beta oxidation and releases an NADH each time. The final C4 molecule is converted to acetyl-CoA
Which of the following statements is consistent with the incorrect conclusion that HCl is an ionic compound?
A 1 M solution conducts electricity
Kaplan Fl4 Q29. An axon can be modeled as a repeating array of resistors and capacitors; one model is shown below. R and C are resistance and capacitance of the membrane, respectively. After the switch is closed, how does the voltage at point V1 change over time?
A. (Exp. when battery resistor and capacitor are in series, the voltage on the capacitor starts at 0 and charges higher and higher until it reaches the voltage of the battery.)
Kaplan FL5 Q30. Energy is removed from the body by all of the following types of heat transfer EXCEPT:
All of the above are ways that heat leaves the body through skin and sweat. Radiation convection and conduction.
Kaplan FL4 Q37. The calorimeter must be thermally isolated so that:
All the heat released by the smaple will be absorbed by the bomb and all the water. (Exp. No heat leaves the system cause it is thermally isolated so it is absorbed by water and the bomb. Not just the water)
Kaplan FL4 Q13. An arteriole is almost completely blocked by a blood clot as shown below. At which point will the velocity of blood flow be the greatest? (Assume ideal laminar flow throughout. Diagram is drawn to scale.)
B. Use V1A1 = V2A2
Kaplan FL5 Q51. A new study reports the discovery of a novel phospholipase that cleaves only saturated fatty acids "tails" from phospholipids and replaces them with unsaturated fatty acid "tails". which of the following effects of the novel phospholipase would be observed?
The fluidity of a cellular lipid bilayer is increased. (exp. Unsaturated fatty acids have double bonds. This causes kinks and prevents from stacking. This would increase the fluidity)
Kaplan FL4 Q49. Melanin, which is found in its greates concentrations in the three outermost layers of the epidermis, was studied to determine its absorptive ability. The results are shown below. Under which of the following conditions would someone produce the most Vitamin D3?
Low epidermal melanin concentrations and exposure to 320 nm light. (Exp. light has to reach the two deepest layers of the skin to make vitamin D3. so melanin must be in low concentration so the light can penetrate. UVB light (270 - 330nm) is for vitamin D3.)
Kaplan FL5 Q37. The student concludes from her observations that Compound A is a tertiary alcohol and Compound D is a primary alcohol. Which additional piece of information supports her conclusion?
Compound D is a better reducing agent than Compound A. (exp. Compound A is tertiary alcohol and cannot be oxidized at all. So it is a poor reducing agent. Thus, the primary alcohol, which can be oxidized is a better reducing agent and (A) is the correct answer.)
Kaplan FL5 Q19. Norepinephrine causes constriction of blood vessels. If a certain blood vessel is constricted to half of its diameter yet maintains the same pressure gradient, according to Poiseuille's Law, the volumetric flow rate is expected to:
Decrease by a factor of 16. (exp. Poiseuille flow is Q=(P(pi)(r^4))/(8(uL))
Kaplan FL4 Q25. Physicians recommend drinking more water when one is at risk for kidney stone formation. This measure prevents all categories of stones because it increases urine volume while:
Having no efect on the number of moles of all solutes in the kidney. (Exp. increasing water consumption increases fluid output. But the same number of moles of ions taken in the body is still the same. Concentration decreases)
Kaplan FL5 Q15. At the end of the synthesis, proline is extracted from the reaction mixture. Which of the follwoing types of intermolecular forces are likely present in the proline solution?
Hydrogen bonds, Ion-dipole foces, Dispersion forces, and dipole-dipole forces.
Kaplan FL4 Q23. Disorders that increase the metabolic breakdown of which of the following biological molecules are considered a direct risk factor for uric acid kidney stones?
I. ATP and II. DNA (Exp. Uric acid is produced from breakdown of purines. adenine is in ATP. DNA contains purines. Urea was not mentioned)
Kaplan FL4 Q28. Which forward reaction would be expected to have the larger equilibrium constant?
II, because Y is more stable than X (Exp. Y is a 5-carbon ring and X is a 3-carbon ring. 5 carbon rings are more stable. More stable means it will.)
A student receives a solution containing an unknown anion and is required to characterize the identity of the anion. Which of the following NOT a plausible conclusion the student could make?
If dilute ammonia, followed by BaCl2, is added to the unknown and a yellow precipitate forms, then the anion is NO3-.
Kaplan FL5 Q53. What could account for the difference in capacitance per area between myelinated axon and unmyelinated axon?
In unmyelinated axons, the lipid bilayer is thinner.
Kaplan FL4 Q46. Which of the following statments is true of acetone?
It exists as a pair of tautomers, of which the keto form predominates. (Exp. The Carbon oxygen double bond is much stronger than the carbon-carbon double bond)
Kaplan FL5 Q55. Sodium and potassium are the ions primarily responsible for conduction of the impulse down the axon. Which of the following correctly orders the atoms by the size of their radii?
K>K+>Na+
Kaplan FL5 Q27. Based on the two stereoisomers of alanine shown below, which of the following is true about alanine?
L-alanine could also be called (S)-alanine.
Kaplan FL4 Q41. Which of the following acids will be most susceptible to lipid peroxidation?
Linoleic acid CH2(CH2)4CH=CHCH2CH=CH(CH2)7COOH. (Exp. lipid peroxidation requires an unsaturated fatty acid. Having a double bond makes it more susceptible to removal of H and an electron. The mechanism shows this. So linoleic acid has 2 double bonds)
Kaplan FL5 Q25. The researcher concludes from his experiment that the only reason lead is an excellent shielding material for X-rays is because it has a high atomic weight. Is the researcher's conclusion correct?
No, because gold is a better shielding material than lead. (exp. gold has a higher absorbance)
The SOD-catalyzed reaction of superoxide anion is an example of disproptionation because:
O2- is both reduced and oxidized. (Exp. O2- turns into O2 and H2O2. So both oxidation and reduction are occuring)
Kaplan FL4 Q15. Two pigments are nearly identical and differ only in the lengths of their conjugated polyene chains. Pigment A transmits yellow light and Pigment B transmits red light. What can be said about the sizes of the chromophores. ?
Pigment B has a longer chain. (explanation: the wavelength that is absorbed generally increases with the number of conjugated bonds. More conjugated bonds means it is bigger)
Kaplan FL4. Q5. Derivatives of phosphatidic acid, such as phosphatidylinositol, are found in the mylin sheath that surrounds neurons. Such compounds are likely incorporated beause they are:
Poor conductors, which help myelin speed up action potential transmission.
Kaplan FL4 Q9. If the elastic component of the models were removed, which of the following would be true of the visous component?
Rate of flow would be proportional to the pressure difference between adjacent locations until flow became turbulent.
Kaplan FL5 Q20. What is the likely effect on AchE of a temperature much higher than 42C?
Secondary and tertiary structure breakdown only
Kaplan FL4 Q8. Which of the following graphs best illustrates the elongation visoelastic material as modeled by the diagram below?
See Test.
Kaplan FL4 Q27. Increasing consumption of dietary calcium has been shown to decrease the ris of calcium oxalate stone formation, while consumption of calcium supplements has been shown to increase risk. If true, which of the following would best resolve this contradiction?
Supplements are most often taken without food, and dietary calcium can prevent ingested oxalate from being absorbed.
What is the best explanation for the fact that a solution of NaNO2(aq) is basic?
The NO2- reacts with water, forming OH- ions
Kaplan FL4 Q6. Why does the Voigt model indicate an asymptotic limit of elongation during constant stretch over time while the Maxwell model does not?
The ability of the viscous component to stretch infinitely is limited by the elastic component.
Kaplan FL 4 Q12. The reaction coordinate diagram below shows the progress of a reaction catalyzed by carbonic anhydrase. If topiramate (an inhibitor of carbonic anhydrase) were added to the reaction vessel, how would the reaction most likely be affected?
The activation energy would increase.
Kaplan FL5 Q2. Two identical balloons of negligible mass are tethered at altitudes of 2000 meters and 2600 meters, respectively. The balloons are filled with helium gas to equal volumes. Which of the following statements is true concerning the buoyant force acting on each balloon?
The buoyant force on the balloon at 2000 meters will be greater. (exp. more pressure at 2000 meters so it will result in a greater buoyant force)
Kaplan FL5 Q16. Since several different mechanisms underlying the proline-catalyzed reaction have been proposed, a researcher sets out to verify whether it actually occurs via an enamine mechanism. He runs the reaction in the presence of 18O-enriched water. Which of the following findings support the enamine mechanism outlined in the passage?
The carbonyl oxygen of the beta-hydroxyketone carries the isotopic label
Kaplan FL4 Q36. A heater is used to calibrate a constant-volume calorimeter. After operating the heater inside the bomb, which of the following physical quantities must be determined? (Note: The bomb and the water surronding it remain in thermal equilibrium.)
The change in temperature of the water, the power of the heater, and the total time the heater was operated. (Exp. Q=C(deltaT) C is heat capacitance and that is given as Kj so to determine the amount of Kj you need to know the time and power of the heater. change in T is by increase in temp of water)
Kaplan FL5 Q1. The decrease in temperature of a parcel of hot air rising from a smoke stack is a result of:
The expansion of the parcel (exp. It is adiabatic so there is no transfer of heat. The parcel of hot air rises, it expands approximately adiabatically doing work on the surrounding air"
Kaplan FL4 Q50. Pyrocalciferol and lumisterol can be seperated on the basis of:
The fact that the two molecules will have different physical properties. (Exp. diasteroemers have different chemical and physical properties from eachother)
