Missed C/P Questions Flashcards
(166 cards)
1
Q
What was the principal factor determining the migration of individual components in the sample with paper chromatography?
A
Hydrogen bonding. The relative amount of hydrogen bonding to the stationary phase will determine the relative rate of migration of the various components in the sample.
2
Q
What type of functional group is formed when aspartic acid reacts with another amino acid to form a peptide bond?
A
An amide group
3
Q
What is the difference between an Amine and an Amide
A
The main difference between amine and amide is the presence of a carbonyl group in their structure; amines have no carbonyl groups attached to the nitrogen atom whereas amides have a carbonyl group attached to a nitrogen atom.
4
Q
What type of reaction forms a peptide bond? What is the leaving group?
A
Condensation or dehydration synthesis. H2O is leaving group
5
Q
Which of the following will decrease the percentage ionization of 1.0 M acetic acid, CH3CO2H(aq)?
A.Chlorinating the CH3 group
B.Diluting the solution
C.Adding concentrated HCl(aq)
D.Adding a drop of basic indicator
A
The answer to this question is C because HCl is a strong acid that will increase the amount of H+ in solution and thus decrease the percentage of CH3CO2H that ionizes.
6
Q
The intensity of the radiation emitted by the oxygen sensor is directly proportional to the:
A.propagation speed of the radiation.
B.wavelength of the radiation.
C.polarization of photons emitted.
D.number of photons emitted.
A
The answer to this question is D because the energy of electromagnetic radiation is directly proportional to the number of photons, and the intensity of electromagnetic radiation is defined as energy emitted per unit time. Thus, intensity is directly proportional to the number of photons emitted
7
Q
What is the conversion from Hz to THz?
A
1 Hertz = 1x10^-12 THz
8
Q
What is standard atmospheric pressure in mmHg, Torr, and atm?
A
760 mmHg, 760 Torr, 1 atm
9
Q
What does lipase do?
A
Lipase is an enzyme that breaks down dietary fats into smaller molecules called fatty acids and glycerol.
10
Q
Which type of bond is formed by glycogen synthase upon release of UDP?
A.α-1,4-Glycosidic bond
B.α-1,6-Glycosidic bond
C.β-1,4-Glycosidic bond
D.β-1,6-Glycosidic bond
A
The answer is A because the bond that is formed by glycogen synthase is the main chain linkage of glycogen, which is an α-1,4-glycosidic bond. UDP release means that only glucose was added.
11
Q
What types of bonds occur with glycogen branching?
A
Branching occurs through an α-1,6-glycosidic bond in glycogen.
12
Q
Each of the following equations shows the dissociation of an acid in water. Which of the reactions occurs to the LEAST extent?
A.HCl + H2O → H3O+ + Cl−
B.HPO42− + H2O → H3O+ + PO43−
C.H2SO4 + H2O → H3O+ + HSO4−
D.H3PO4 + H2O → H3O+ + H2PO4−
A
The answer to this question is B. HPO42− has a high negative charge and so dissociation of it will occur to the least extent.
13
Q
Which of the following most likely will occur if a homogeneous catalyst CANNOT be separated from the products at the end of a reaction?
A.The catalyst will become heterogeneous.
B.The products will be contaminated.
C.The reaction will not occur.
D.The reaction rate will speed up.
A
The answer to this question is B. If a homogeneous catalyst cannot be separated from the products at the end of a reaction then the products will be contaminated with the catalyst. I
14
Q
How will the rate of a catalyzed reaction be affected if the solid catalyst is finely ground before it is added to the reaction mixture?
A.The rate will be faster because a greater mass of catalyst will be present.
B.The rate will be faster because a greater surface area of catalyst will be exposed.
C.The rate will be slower because the fine catalyst particles will interfere with product formation.
D.The rate will remain the same because the mass of catalyst will be the same.
A
The answer to this question is B because grinding a heterogeneous catalyst increases the amount of catalyst available to the reaction and therefore increases its rate.
15
Q
Which measurement unit CANNOT be used to express power?
A.kg•m2 •s2
B.J•s-1
C.ft•lb •s-1
D.W
A
The answer to this question is A because the measurement unit of power is watt, defined as J/s = ft•lb/s = kg•m2/s3.
16
Q
What is the equation for dB?
A
1dB = 10 log10(I/I0)
where I0 is a reference intensity equal to the human threshold of hearing, 10–12 W/m2
17
Q
The mathematical expression for h is:
A. mv2/2.
B. v2/(2g).
C. mg.
D. mv.
A
The correct answer is B.
Conservation of energy implies KEinitial = PEfinal, or mv2/2 = mgh; therefore, h = v2/2g. Thus, B is the best answer.
18
Q
How do you find λ using frequency (f) ?
A
λ = vsound/f
19
Q
What does the focal length of a mirror depend on?
A
The radius of the curvature
20
Q
Visible light travels more slowly through an optically dense medium than through a vacuum. A possible explanation for this could be that the light:
A. is absorbed and re-emitted by the atomic structure of the optically dense medium.
B. is absorbed and re-emitted by the nucleus of the material in the optically dense medium.
C. bounces around randomly inside of the optically dense medium before emerging.
D. loses amplitude as it passes through the optically dense medium.
A
The correct answer is A.
A is known to occur and is the reason for the slowing down of light. B is incorrect because the nucleus is involved. C is incorrect because the motion of the photons is certainly not random. D is true but does not answer the question. Thus, A is the best answer.
21
Q
Which circuit elements store energy?
Capacitors
Resistors
Batteries
A
Capacitors and Batteries
22
Q
How do you find the pressure in a cylinder contain a liquid?
A
Pressure is given by (density) • g • (height)
23
Q
What are the relationships between intensity and dB?
A
10x intensity = 10^1 = 10 dB
100x intensity = 10^2 = 20 dB
1000x intensity = 10^3 = 30 dB
This is because β = 10Log(I/I0)
24
Q
A climber using bottled oxygen accidentally drops the oxygen bottle from an altitude of 4500 m. If the bottle fell straight down this entire distance, what is the velocity of the 3-kg bottle just prior to impact at sea level? (Note: ignore air resistance)
What equation would you use to solve this?
A
A is correct. As an object falls, the kinetic energy (KE) that it gains is equal to the potential energy (PE) that it loses. Thus, for this object, we can say that 1/2m(vfinal)2 = mgΔh, where g ~ 10 m/s2:
½(3) (vfinal)2 = 3(10) (4500)
(vfinal) 2 = (10)(4500)(2)
(vfinal) 2 = 9 x 104
vfinal = 3 x 102 m/s = 300 m/s
25
The hemoglobin (Hb) dissociation curve at high altitude has a distinct shape from that at atmospheric pressure. Which of the following best explains this shape?
D is correct.
The sigmoidal shape of the curve implies that as each oxygen molecule binds to Hb, the affinity of Hb for oxygen goes up. Homotropic regulation is when a molecule serves as a substrate for its target enzyme, as well as a regulatory molecule of the enzyme's activity. O2 is a homotropic allosteric modulator of hemoglobin. The four subunits of hemoglobin actually bind to oxygen cooperatively, meaning the binding of oxygen to one of the four subunits will increase the likelihood that the remaining sites will bind with oxygen as well. This is the cause of the sigmoidal curve shown in the figure.
26
Homotropic regulation
Homotropic regulation is when a molecule serves as a substrate for its target enzyme, as well as a regulatory molecule of the enzyme's activity. O2 is a homotropic allosteric modulator of hemoglobin.
27
Fluid pressure changes with depth are assumed to be linear. Which statement best explains why this does not hold true for atmospheric pressure changes?
A. At very high temperatures, air behaves less ideally.
B. The volume of a mass of air is not constant.
C. The majority of molecules in air are nonpolar.
D. Air is not of a uniform composition.
B is correct. Hydrostatic pressure for liquids is linear because as depth changes, the density of the liquid remains constant. Gases, however, have densities that change according to the forces applied to them. Gases are compressible, while liquids and solids are not.
28
State what you know about the properties of gases
Gases lack a fixed shape and volume. The lack of a fixed volume—or compressibility—is especially important because it means that the density of a given gas is not constant. Rather, if the gas is forced into a smaller container, its density will increase as its particles pack more closely together
29
Melting/Fusion
Solid to liquid
30
Evaporation
Liquid to gas
31
Sublimation
Solid to gas
32
Condensation
Gas to liquid
33
Freezing
Liquid to solid
34
Deposition
Gas to solid
35
What are the endothermic phase changes?
melting, evaporation, and sublimation
36
What are the exothermic phase changes?
condensation, freezing, and deposition
37
What are the pKa's of titration indicators?
```
Methyl orange 3.7
Bromophenol blue 4.0
Methyl red 5.1
Bromothymol blue 7.0
Phenol red 7.9
Phenolphthlein 9.3
```
38
What is the difference between a positive control group and a negative control group?
A positive control is a control group that is not exposed to the experimental treatment but that is exposed to some other treatment that is known to produce the expected effect.
A negative control group is a control group that is not exposed to the experimental treatment or to any other treatment that is expected to have an effect.
39
Cross Sectional Design Study
Cross-sectional studies investigate a population at a single point in time, looking for predictive relationships among variables. A limitation of cross-sectional designs is that they can show correlations, but not causation, because looking at changes over time is necessary to assess whether a cause-and-effect relationship is present.
40
Experimental design study
An experimental design involves manipulating a certain variable—known as an independent variable—to see what effects it has. The measured effects are known as dependent variables. Additional types of study design exist, especially in the social sciences; of note, qualitative research focuses on analyzing experiences rather than objective metrics.
41
How do you find % dissociation?
[H+]/[HA] x 100%
42
What is the Units of Power (P)?
```
1 Watt (W)
Nm/s or J/s
```
43
What is the half life equation?
(1/2)^n
44
What is ADP to ATP?
ADP is OXIDIZED to ATP
45
When are the inductive effects the strongest?
Inductive effects increase if the electron-withdrawing groups are closer to the acid and if more of them are present
46
Suicide inhibition
also known as suicide inactivation or mechanism-based inhibition, is an irreversible form of enzyme inhibition that occurs when an enzyme binds a substrate analog and forms an irreversible complex with it through a covalent bond during the normal catalysis reaction.
47
How do you find mechanical advantage?
```
MA = hypotenuse / height OR
MA = Fload/Feffort
```
48
A circuit is comprised of a 12-volt battery with three light bulbs with the same resistance. If two of the light bulbs are wired in parallel and are in series with the third light bulb, what happens when one of the parallel light bulbs is unscrewed?
A. All of the light bulbs remain lit.
B. Two of the light bulbs remain lit.
C. One of the light bulbs remains lit.
D. All of the light bulbs go out.
B is correct. Even after unscrewing one of the parallel light bulbs, there is still a circuit for current to flow from the positive terminal to the negative terminal of the battery through the two remaining light bulbs
C, D: The current still has an available path to travel through the branch of the remaining parallel bulb and then through the series bulb. As such, these two remaining light bulbs will stay lit.
49
Air is bubbled through distilled water. The solution will have a pH:
A. greater than 7, because elemental nitrogen undergoes hydrolysis.
B. less than 7, because elemental nitrogen undergoes hydrolysis.
C. greater than 7, because carbon dioxide undergoes hydrolysis.
D. less than 7, because carbon dioxide undergoes hydrolysis.
D is correct. Air contains elemental nitrogen as its major component, but elemental nitrogen is essentially inert and is neither an acid nor a base. On the other hand, carbon dioxide can undergo a hydrolysis reaction in liquid water to produce carbonic acid, a weak acid that produces a solution whose pH is less than the pH of water (pH = 7).
50
What is the Rf value in paper chromatography?
The Rf value is defined as the ratio of the distance moved by the solute (i.e. the dye or pigment under test) and the distance moved by the the solvent (known as the Solvent front) along the paper, where both distances are measured from the common Origin or Application Baseline, that is the point where the sample is initially spotted on the paper.
51
Which of the following molecules will have the highest Rf value when studied with thin-layer chromatography using a silica plate?
A. CH3CH2CH2CH2CH3
B. HOCH2CH2CH2CH3
C. HOCH2CH2CH2OH
D. HOOCCH2CH2CH3
A is correct. Silica is a highly polar molecule; thus, when chromatography is done on a silica plate, a polar substance will move slower on the plate due to polar-polar interactions between the substance and the plate. This means that the Rf value of a polar substance will be smaller than that of a nonpolar substance since the substance will move less on the plate compared to the solvent front than a nonpolar substance would. Of the options given, the compound in answer choice A is the least polar.
52
When a patient is on the operating table for heart surgery, surgeons need to clamp major nearby blood vessels before cutting them because, according to Bernoulli's equation, a volume of pressurized blood opened to the atmosphere:
A. will convert its pressure to kinetic energy, rapidly exiting the body and causing shock.
B. will convert its pressure to potential energy, pooling at the high places of the body and causing a potential brain aneurysm or stroke.
C. will match outside pressure by decreasing fluid speed, starving the body of oxygen.
D. is at risk of over-oxidizing, dangerously increasing pressure.
A is correct. When the surgeons cut into the artery, blood will obviously shoot out of the body as a result of blood pressure. That pressure is converted to kinetic energy, causing the blood to move rapidly as it exits the body.
53
Ritonavir is an antiviral drug that mimics the natural substrate for a key viral protease enzyme. As a competitive inhibitor, ritonavir:
A. decreases the rate of reaction because it decreases the availability of ATP to catalyze the reaction.
B. increases the rate of reaction by altering the tertiary structure of the enzyme.
C. decreases the rate of reaction by binding to the enzyme and altering the structure of its active site.
D. decreases the rate of reaction by binding to the active site.
D is correct. This question is asking us for the definition of a competitive inhibitor, which binds to the active site and blocks the substrate from attaching. The mechanism of a generic competitive inhibitor is depicted below.
54
A ray of light in air strikes the flat surface of a liquid, resulting in a reflected ray and a refracted ray. If the angle of reflection is known, what additional information is needed in order to determine the relative refractive index of the liquid compared to air?
A Angle of incidence
B Angle of refraction
C Refractive index of air
D Wavelength of the light
Solution: The correct answer is B.
To find the relative refractive index to air one needs both the incident and refracted angles. Since the angle of incidence is equal to the angle of reflection we will know the angle of reflection. We still must know the angle of refraction and this is answer B. None of the other answers will allow one to know the angle of refraction.
55
If the magnitude of a positive charge is tripled, what is the ratio of the original value of the electric field at a point to the new value of the electric field at that same point?
A 1:2
B 1:3
C 1:6
D 1:9
Solution: The correct answer is B.
The magnitude of the electric field E of a point charge is given by
E=kq/r^2
If q is tripled, E also will be tripled. Thus, B is the best answer.
56
Underproduction of pulmonary surfactant in IRDS leads to decreased compliance of alveolar tissue. Based upon this information, which of the following must be true regarding pulmonary surfactant?
A. Its adsorption to the water-alveolar interface increases surface tension, preventing alveolar collapse due to intra-thoracic pressure.
B. Its absence decreases the minimum radial size of alveoli able to avoid collapse at a given pressure of inspired air.
C. Its adsorption to the water-alveolar interface decreases surface tension, decreasing the pressure difference required to inflate the airway.
D. Its presence increases the efficiency of gas exchange across the alveolar membrane by decreasing the surface area of the alveolus at a given pressure of inspired air.
C is correct. During inspiration, contraction of the diaphragm and external intercostal muscles leads to expansion of the thoracic cavity and a decrease in intrapleural pressure. This negative pressure, relative to atmospheric pressure at the entry of the upper airway, generates airflow through the respiratory tree and to its terminal extension—the alveoli. The elastic recoil force of the airway and the surface tension of the water lining the airway oppose expansion of the alveoli due to the influx of atmospheric pressure. Pulmonary surfactant adsorbs to the air-water-alveoli interface, reducing surface tension and the total force resisting expansion. This increases pulmonary compliance—a measure of lung volume change at a given pressure of inspired air—and decreases the work required to expand the lungs at a given atmospheric pressure. This is consistent with choice C.
In general, surfactant molecules are amphipathic, meaning that they contain both hydrophobic and hydrophilic regions. The diagram below shows surfactant molecules surrounding a micelle of oil. The hydrophobic tails of the surfactant molecules mix well with the hydrophobic oil, while the hydrophilic heads point away from the oil droplet.
57
the hydrophobic solute-solute interaction is spontaneous, and that ΔH and ΔG have opposite signs. Which of the following must be true for this interaction when temperature is a positive value?
I. ΔH > ΔG
II. 0 < ΔS
III. ΔH < ΔS
A. I only
B. I and II only
C. II and III only
D. I, II, and III
B is correct. For the interaction to be spontaneous, the free energy change of the reaction must be negative. The question states that the enthalpy and free energy changes for the interaction have opposite signs. Thus, ΔG is negative and ΔH is positive, making Roman numeral I true. For a reaction to be both endothermic (positive ΔH) and spontaneous (negative ΔG), the reaction must involve an increase in entropy (ΔS is positive).
This is according to the equation: ΔG = ΔH - TΔS.
Thus, II is also true because ΔS is positive.
III: The quantity TΔS, not ΔS, must be greater than ΔH. For this reason, RN III does not have to be true.
58
Figure 1 shows a drop in the first ionization energy in going from beryllium to boron. Which of the following best explains the source of this drop?
A. Boron contains one valence electron, while beryllium contains none.
B. After putting two electrons in the valence s-type subshell for beryllium, the third valence electron for boron must enter an orbital that already contains an electron of opposite spin.
C. The two valence electrons for ground state beryllium are in an orbital with an azimuthal quantum number of l = 0, whereas the third valence electron in ground state boron must be in an orbital with an azimuthal quantum number of l = 1.
D. The two valence electrons for ground state beryllium are in an orbital with a magnetic quantum number of m = +1, whereas the third valence electron in ground state boron must be in an orbital with a magnetic quantum number of m = -1.
C is correct. The electron configuration for beryllium is 1s22s2. The azimuthal quantum number for an s-type orbital is l = 0, which defines the shape of the electron cloud (a spherically-shaped electron wave, with no nodes). For boron, since the s-type orbital in the valence shell cannot hold more than two electrons, the third valence electron must be placed into a p-type orbital, giving an electron configuration of 1s22s22p1. The azimuthal quantum number for a p-type orbital is l = 1 (a dumbbell-shaped electron wave with one node at the nucleus). The 2p orbital is slightly higher in energy than the 2s orbital, making it slightly easier to ionize this electron. Choice C is the only answer option that correctly describes this situation.
The shapes of the s-type and p-type orbitals are shown below. (Note that multiple possible shapes exist for p-type orbitals.)
59
What is first ionization energy?
The first ionization energy is the energy required to remove one mole of the most loosely held electrons from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of 1+.
60
What molecules have higher first ionization energies?
Helium has the highest. All of the noble gases and halogens have high ionization energies. The period 2 elements also have high ionization energies.
Francium (FR) in the bottom left of the periodic table has the lowest
61
What does the quantum number (n) denote?
It denotes the energy level of the electron, and can take any integer value (≥1). Higher principal quantum numbers (for example, n = 2 rather than n = 1) have greater energy and are farther from the nucleus. The principal quantum number relates to the row of the periodic table in which the element in question is found.
62
What does the quantum number (l) denote?
The azimuthal, or angular momentum, quantum number (l) describes the subshell of the principal quantum number in which the electron is found, with values ranging from 0 to n − 1, where l = 0 is the s subshell, l = 1 is the p subshell, l = 2 is the d subshell, and l = 3 is the f subshell
63
What does the quantum number (ml) denote?
(ml) describes the spatial orientation of the orbital in question within its subshell. Potential values of ml range from −l to +l. Since each orbital can hold a maximum of two electrons, this means that an s subshell can contain up to two electrons, a p subshell can hold up to six electrons, a d subshell can contain up to 10, and an f subshell can hold up to 14.
64
What does the quantum number (ms) denote?
(ms) describes the spin orientation of the electron, which relates to its angular momentum. The two possible spin orientations are ms = −1⁄2 and ms = +1⁄2. Two electrons in the same orbital (and thus with the same ml value) are said to be paired and must have opposite spin.
65
Which of the following electronic transitions for a hydrogen atom would result in the emission of a photon that would be visible to the human eye?
A. n = 1 to n = 3
B. n = 2 to n = 4
C. n = 2 to n = 1
D. n = 4 to n = 2
D is correct. The visible spectrum contains electromagnetic signals with wavelengths ranging from 400 nm to 700 nm. The wavelength of light emitted during a particular electronic transition is determined by the energy difference (ΔE) between the final and initial energy levels. The energy of each level can be determined using Equation 1 and the principal quantum number in question. For light to be emitted at all, an electron must travel from a higher to a lower level, a process that releases energy. This automatically eliminates options A and B; however, we must actually perform calculations to choose between C and D.
66
The high-energy radiation produced by the γ rays has sufficient energy to:
I. generate free radicals.
II. excite electrons to higher energy levels.
III. eject electrons from molecular orbitals.
A. I only
B. I and II only
C. II and III only
The high-energy radiation produced by the γ rays has sufficient energy to:
I. generate free radicals.
II. excite electrons to higher energy levels.
III. eject electrons from molecular orbitals.
A. I only
B. I and II only
C. II and III only
67
Free radicals from ionizing radiation are highly unstable and have carcinogenic effects. These effects are most likely result from damage to:
A. proteins.
B. phospholipids.
C. the Golgi apparatus.
D. nucleic acids.
D is correct. The question stem states that free radicals can cause cancer, which is a result of poorly regulated cell growth and division. Cancer is generally a product of mutations in DNA that disrupt these processes. Therefore, we must choose the answer that targets DNA, which is choice D.
68
A person pushes horizontally on a 50-kg crate, causing it to accelerate from rest and slide across the surface. If the push causes the crate to accelerate at 2.0 m/s2, what is the velocity of the crate after the person has pushed the crate a distance of 6 meters?
What equation should you use here?
he appropriate kinematic equation is vf2 = vi2 + 2ad.
69
In a follow-up study, the emission spectra of both bound states of Y32 were shifted to longer wavelengths than the excitation spectra shown in Figure 2. What is the most likely cause of this shift?
A. The emission intensity peak is usually lower than the excitation peak.
B. There is a loss of vibrational energy when electrons move from the excited to the ground state.
C. A fluorophore typically excited at a wavelength at the peak of the excitation curve.
D. Emission detection was selected at the peak of the emission curve.
B is correct. Longer-wavelength light corresponds to lower-energy light. If the energy required to excite electrons present in the CPV fluorophore exceeded that which is emitted when the electrons relaxed, then energy must have been lost during the return to the ground state following excitation separately from the energy of the emission. Only choice B, which states that there is a loss of vibrational energy during the transition, provides a possible explanation consistent with this requirement.
70
If a scientist chooses not to employ a SEC column, but wishes to fractionate a protein sample on the basis of only molecular weight, what technique would be most appropriate?
A. Affinity chromatography
B. Ion-exchange chromatography
C. SDS-PAGE
D. NMR spectroscopy
C is correct. SDS-PAGE is an electrophoretic technique which involves the binding of the anionic detergent SDS to a polypeptide chain. SDS binding denatures and imparts an even distribution of charge per unit mass to the protein, resulting in fractionation by approximate size alone during electrophoresis.
71
More complete fractionation of proteins using an SEC column could be achieved by using a:
A. nonpolar solvent.
B. vacuum across the column.
C. larger protein sample concentration.
D. longer column.
D is correct. As with other forms of chromatography, increasing the column length will enhance the resolution of the column, leading to more completion fraction by SEC. This is because the material of the matrix provides the physical means of separating the proteins. If the proteins come in contact with a longer length of matrix, the differences in retarding forces experienced by the proteins will have a greater cumulative influence on the migration of the proteins, lengthening the differences in their retention times.
72
What is absolute configuration?
An absolute configuration refers to the spatial arrangement of the atoms of a chiral molecular entity (or group) and its stereochemical description e.g. R or S
73
What kind of configuration is D and L?
Relative configuration
74
What is the pH of a 0.10 M aqueous solution of acetylsalicylic acid?
A. 1.0
B. 2.3
C. 3.5
D. 4.1
B is correct. Acetylsalicylic acid is a weak acid, with a pKa of 3.5. Therefore, the pH of this solution must be less than the pKa, because the compound is primarily in its acid form and a pH of 3.5 would mean that the concentration of weak acid and conjugate base were equal (a buffer). Choices C and D can be eliminated. A pH of 1.0 for an acid whose concentration is 0.10 M would require complete dissociation (as in a strong acid), eliminating choice A. Alternatively, the pH can be determined from the equilibrium expression:
75
Galvanic cells always have cell potentials ______ than zero
greater
76
How do you find E cell?
Ecell = E°cathode − E°anode
77
Electrolytic cells always have cell potentials ______ than zero
Less
78
How do you find capacitance?
C=q/V
79
How can you find charge?
q=VC
80
Which of the following electronic transitions for hydrogen would result in the emission of a quantized amount of energy?
A. n = 1 → n = 2
B. n = 2 → n = 3
C. n = 5 → n = 4
D. n = 4 → n = 6
C is correct. In order to emit a photon carrying energy, an electron must go from a higher energy level to a lower energy level. Only choice C shows such a transition.
81
During strenuous exercise, lactic acid buildup in cells causes the creation of a hydronium complex known as the Eigen cation (H9O4+). If water molecules then experience hydrogen bond attractions to the Eigen cation, this attractive force:
A. results in a semi-stable shell of water molecules around the hydronium.
B. results in an inability of hydronium to be neutralized by bases the way normal H+ ions would be.
C. results in the ability of muscle cells to reverse both the hydronium creation process and the lactic acid creation process once sufficient oxygen is once again made available.
D. results in mobility of hydronium within the environment surpassing the mobility of regular water molecules.
A is correct. A process known as “hydration” or “solvation” occurs when the attractive force of an ion molecule causes a thin shell of water molecules to surround it. In the case of hydronium (H3O+), each of the H atoms attracts the O atom in an H2O molecule due to hydrogen bonding. These H2O molecules cause a “shell” of water molecules to surround the hydronium.
82
When does a runner output the most additional energy to keep the ground reaction forces most nearly vertical and through her body’s center of mass?
A. When she takes high, bouncing strides and keeps her spine fairly vertical
B. When she takes long, low strides and keeps her spine fairly vertical
C. When she takes high, bouncing strides and leans her upper half into her run
D. When she takes long, low strides and leans her upper half into her run
C is correct. Both the vertical displacement of the runner's steps and the angle of her body from the vertical increase the energy required to realign the ground reaction forces. Recall that tanθ = sinθ/cosθ, so when θ is close to zero, so is tanθ. When θ is close to 90°, tanθ becomes arbitrarily large. The more the runner leans into the run, the greater (or closer to 90°) tanθ is, and the greater the work expended by the runner must be, according to the work equation given in the passage (Wx = Fz tan(θ) Δz). Also, in this equation, the passage states that Δz represents the vertical displacement of a single step. Thus, the higher the vertical displacement ("high, bouncing strides..."), the greater the energy expenditure.
83
What is the potential energy of a spring?
PEelastic = ½kx2
84
A balloon has a volume of 3.0 L at 25°C. What is the approximate volume of the balloon at 50°C?
A. 1.5 L
B. 2.0 L
C. 3.3 L
D. 6.0 L
C is correct. Charles’ law states that there is a direct relationship between the volume of an ideal gas and its temperature, when pressure is constant. Note that the temperature must be in Kelvin! We can approximate the initial temperature as 300 K and the final temperature as 320 K.
(3.0 L)/(300 K) = V2/(320 K)
[(3.0)(320)] / (300) = (3.0)(1.1) = 3.3 L
85
What is Charles's Law?
Charles' Law is a special case of the ideal gas law. It states that the volume of a fixed mass of a gas is directly proportional to the temperature. This law applies to ideal gases held at a constant pressure, where only the volume and temperature are allowed to change. Charles' Law is expressed as: Vi/Ti = Vf/Tf
86
Which of the following best explains why arginine is more basic than lysine?
A. The electron-donating groups around the basic nitrogen on arginine make its conjugate base less stable.
B. The electron-donating groups around the basic nitrogen on arginine make its conjugate acid more stable.
C. The lack of electron-donating groups on lysine make its conjugate acid more stable.
D. The lack of electron-withdrawing groups on lysine make its conjugate base more stable.
B is correct. This question is asking us to determine why arginine is more basic than lysine. The reason must be related to how arginine is better able to handle being protonated, as this is the essence of being a base. Since, in its protonated form, arginine has electron-donating groups via resonance with other nitrogens, it is a more stable conjugate acid.
The resonance structures of arginine at this position are shown below. Note that the backbone amino and carboxylic acid groups are deprotonated, meaning that this is the structure of arginine at relatively high pH (albeit not high enough to deprotonate the side chain).
87
If a flat Petri dish containing a single layer of cells suspended in viscous culture medium is tapped, some cells will collide into each other. If cell 1 collides into cell 2 on such a plate, which of the following describes what happens to cell 2 after the collision, assuming an elastic collision and non-zero drag from the medium?
I. Cell 2 continuously accelerates.
II. Cell 2 moves with decreasing speed.
III. Cell 2 moves with constant speed.
IV. Cell 2 decelerates until it reaches a velocity of 0 m/s.
A. I only
B. II only
C. III only
D. II and IV only
D is correct. Cell 2 can only accelerate while it is being pushed/in contact with cell 1, so statement I is false. Since the cells experience drag from the medium, cell 2 will decelerate after the collision, making statement II correct and statement III incorrect. The drag will cause cell 2 to continuously decelerate until it comes to rest.
88
How do you know how many stereoisomers something has?
The 2^n rule.
| N is the number of chiral centers in the molecule
89
When do you get a precipitate in regards to the Ksp?
When the concentration exceeds the Ksp
| [A][B] > Ksp
90
Where do electric field lines point/go?
They go in a positive to negative direction because they want to go in the way that a positively charged molecule would go
91
What shows silver in Tollen's test?
also known as silver-mirror test, is a qualitative laboratory test used to distinguish between an aldehyde and a ketone. It exploits the fact that aldehydes are readily oxidized (see oxidation), whereas ketones are not. Therefore Ketone's will not become silver
92
What does the y-intercept represent in a line Weaver-Burke plot?
1/Vmax
93
What does the x-intercept represent in a line Weaver-Burke plot?
1/Km
94
NADPH--> NADP+
What is happening?
What is oxidizing agent?
What is reducing agent?
This is an oxidation reaction
| NADPH is the oxidizing agent
95
1 L = ? cm3
1000
96
What is m^3 to cm^3?
1 m^3 = 10^6 cm^3
97
An ultrasound examination could show the motion of a fetus. In order to image this motion, the ultrasound examination devices requires what minimal information?
A.The speeds of the sound and of the moving object.
B.The speed of the sound, and the frequencies of the sound waves emitted and observed.
C.The speeds of the sound and of the moving object, and the frequencies of the sound waves emitted and observed.
D.The speeds of the sound and of the moving object, and the frequencies and wavelengths of the sound waves emitted and observed.
Solution: The correct answer is B.
The answer to this question is B because the Doppler effect is used with ultrasound waves to provide fetal images. The Doppler effect relates the frequency of the ultrasound wave as detected by a moving detector to the frequency of the wave when the source is stationary, the speed of the source, and the speed of the detector. Three of the four quantities involved in the effect are required.
98
The principal quantum number is a measure of which of the following?
A.Approximate radial size of an electron cloud
B.Approximate shape of an electron cloud
C.Number of valence electrons that orbit a nucleus
D.Number of protons and neutrons found in the nucleus of an atom
The answer to this question is A because the principal quantum number n is most closely associated with the potential energy of the electron. Since potential energy is proportional to the square of the distance of two oppositely charged particles by Coulomb’s Law, it is also true that n is associated with the radial “size” of the electron cloud
99
What is the relationship between resistance and temperature?
Linear relationship. If temperature goes up, resistance goes up.
100
Where do we see absorption for a C=O bond in an IR spectra?
The carboxyl group C=O stretching frequency falls in the region 1700–1750 cm–
101
Where do we see absorption for a O-H bond in an IR spectra?
the O–H stretching frequency is expected to fall in the region 3200–3500 cm–1.
102
Where do we see absorption for a N-H bond in an IR spectra?
Sharp peak at 3300 cm-1
103
What is myopia? What type of lens would you use?
Myopia is near sightedness. You would use a diverging lens
104
What is hyperopia? What type of lens would you use?
Hyperopia is farsightedness. You would use a converging lens
105
The density of a human body can be calculated from its weight in air, Wair, and its weight while submersed in water, Ww. The density of a human body is proportional to:
A. Wair/(Wair – Ww).
B.(Wair – Ww)/Wair.
C.(Wair – Ww)/Ww.
D.Ww/(Wair – Ww).
The answer to this question is A because, according to Archimedes’ Principle, the ratio of the density of an object to the density of the fluid it is submersed in is equal to the ratio of the weight of the object in air to the difference of submersed weight and weight in air
106
NADH to NAD+ is what type of reaction?
Oxidation
107
good experimental design protocols state that a good buffer has a pKa within _____ pH unit of the desired experimental conditions.
1
108
What is the visible light spectra?
The wavelength of visible light is between about 400 to 750 nm
109
Finding work done with an elastic force?
W = ksx2/2
110
What do buffer solutions do and what should they consist of?
They are intended to resist changes in pH, and consist of a weak acid or weak base and its corresponding salt.
111
How do you find Solubility Enhancement Ratio? (SER)
SER = (A solubility in MH/A solubility in water)
112
The piezoelectric effect, when generating ultrasound waves, involves the conversion of:
A. chemical energy to mechanical energy.
B. electrical energy to potential energy.
C. kinetic energy to electrical energy.
D. electrical energy to mechanical energy.
D is correct. The piezoelectric effect begins with voltage generating a current through the crystal (electrical energy) and culminates in the crystal vibrating (mechanical energy). Mechanical energy is made up of kinetic and potential energy, as it is associated with the motion and position of an object.
113
All of the following phenomena serve to attenuate the ultrasound signal as it passes through the body EXCEPT:
A. absorption.
B. refraction.
C. scattering.
D. amplification.
D is correct. The question stem asks about attenuation, which is a weakening of the U/S signal. Sound energy is attenuated as it passes through the body because parts of the signal are reflected, scattered, absorbed, refracted or diffracted. Amplification does the opposite of attenuation; it makes the signal stronger. Since this is an "EXCEPT" question, amplification is our answer.
114
What is the range of human hearing?
The range of human hearing is generally considered to be 20 Hz to 20 kHz, but it is far more sensitive to sounds between 1 kHz and 4 kHz.
115
What does the area under the curve of a pressure volume graph give us?
Work done by the engine
116
How do you find the efficiency of an engine?
η (efficiency) = W/QH
117
How do you calculate normality?
Normality can be calculated by multiplying the molarity of the solution by the number of protons per molecule of acid
118
An artery is constricted at one location to 1/2 its normal cross-sectional area. How does the speed of blood past the constriction compare to the speed of blood flow in the rest of the artery? (Note: Assume ideal fluid flow.)
A It is 1/4 as fast.
B It is 1/2 as fast.
C It is 2 times as fast.
D It is 4 times as fast.
In the artery, the product of blood speed and artery cross-sectional area is everywhere constant because the volume flow rates are equal. At the point with half the normal area, the speed must double so that the same volume of blood passes through the constriction as does through the normal part of the artery. Thus, answer choice C is the best answer.
119
How do you get area from diameter? From radius?
A = π d^2/4
A = π r^2
120
How do you get Volume flow rate?
Volume flow rate is the product of blood speed and artery cross-sectional area
121
A magnetic force acts on a moving charge in a direction that is ________ to the velocity of the charge and ________ to the direction of the magnetic field..
perpendicular, perpendicular
122
How do you find t using v and g?
t = 2v/g
123
What would you use to find ions from mols?
Avogadro's number: 6.022x10^23
124
How do you find the magnitude of an electric field using Voltage?
E=V/d
125
What is the equation to find Kcat?
kcat = Vmax/[E]
126
Absorption of ultraviolet light by organic molecules always results in what process?
A.Bond breaking
B.Excitation of bound electrons
C.Vibration of atoms in polar bonds
D.Ejection of bound electrons
The answer to this question is B. The absorption of ultraviolet light by organic molecules always results in electronic excitation. Bond breaking can subsequently result, as can ionization or bond vibration, but none of these processes are guaranteed to result from the absorption of ultraviolet light.
127
Why must the person either lean forward or slide their feet under the chair in order to stand up?
A.To increase the force required to stand up
B.To use the friction with the ground
C.To reduce the energy required to stand up
D.To keep the body in equilibrium while rising
The answer to this question is D because as the person is attempting to stand, the only support comes from the feet on the ground. The person is in equilibrium only when the center of mass is directly above their feet. Otherwise, if the person did not lean forward or slide the feet under the chair, the person would fall backward due to the large torque created by the combination of the weight of the body (applied at the person’s center of mass) and the distance along the horizontal between the center of mass and the support point.
128
Relationship between wavelength and energy?
Longer wavelength equates to lower energy
| E=hc/λ
129
the phosphoryl transfer from kinases comes from the _____ phosphate of ATP
γ (gamma)
130
What type of shape is indicative of a cooperative binding graph
A sigmoidal shape
131
What phenomenon causes static air to be drawn into the mask when oxygen flows?
A.Doppler effect
B.Venturi effect
C.Diffusion
D.Dispersion
The answer to this question is B because oxygen pressure is the sum of the oxygen static pressure P and the oxygen flow pressure ρv2/2. In the area of the mask openings, Pair = P + ρv2/2, thus Pair > P. Air enters the mask because the static pressure of the air is larger than the static pressure of the oxygen in flow. This is the Venturi effect, and the mask is called the Venturi mask.
132
What causes duplex DNA with a certain (A + T):(G + C) ratio to melt at a higher temperature than comparable length duplex DNA with a greater (A + T):(G + C) ratio?
A.Stronger van der Waals forces of pyrimidines
B.Stronger van der Waals forces of purines
C.Increased number of hydrogen bonds
D.Reduced electrostatic repulsion of phosphates
The answer to this question is C. GC base pairs involve three hydrogen bonds, while AT base pairs involve only two. This disparity has often been used to explain the increased melting temperature of DNA rich in GC content.
133
What are the structural features possessed by storage lipids?
A.Two fatty acids ester-linked to a single glycerol plus a charged head group
B.Three fatty acids ester-linked to a single glycerol
C.Two fatty acids ester-linked to a single sphingosine plus a charged head group
D.Three fatty acids ester-linked to a single sphingosine
The answer to this question is B because triacylglycerols are neutral storage lipids. They consist of three fatty acids ester-linked to a single glycerol.
134
Lewis Base vs Lewis Acid
A Lewis acid is therefore any substance, such as the H+ ion, that can accept a pair of nonbonding electrons. In other words, a Lewis acid is an electron-pair acceptor. A Lewis base is any substance, such as the OH- ion, that can donate a pair of nonbonding electrons.
135
How does Gibbs free energy relate to Kf, the formation constant?
ΔG°<0 and spontaneous when K>>1
ΔG°>0 and non spontaneous when K<<1
ΔG°=0 when K=0
136
the Lewis acid–base interaction between a metal cation and an electron pair donor is known as what type of bond?
a coordinate covalent bond
137
Which of the following atoms will be expected to have the smallest second ionization energy?
A.Na
B.C
C.O
D.Ca
The answer to this question is D. Metals have lower ionization energies than non-metals as long as the ionization event involves a valence electron. Since Na is an alkali metal, it has only one valence electron and has a large second ionization energy. Ca is an alkaline earth metal and has two valence electrons. It will therefore have the smallest second ionization energy of the four atoms listed, which include Na and two non-metals.
138
Which of the following species has the largest mass percent of oxygen?
A.H2O
B.CaCO3
C.CO2
D.HCO3–
The answer to this question is A because mass percent of oxygen is calculated by multiplying the coefficient for oxygen in the formula of the substance by 16 and then dividing by the molar mass of the substance. Water has the highest percentage of oxygen by mass of the compounds listed (16/18) × 100 = 89%.
139
How do you find pH if you have pKa?
using the Henderson-Hasselbach equation: pH = pKa + log([base]/[acid]).
140
What is the concentration of Ca2+(aq) in a saturated solution of CaCO3? (Note: The solubility product constant Ksp for CaCO3 is 4.9 × 10–9.)
A.2.4 × 10–4 M
B.4.9 × 10–5 M
C.7.0 × 10–5 M
D.4.9 × 10–9 M
The answer to this question is C. The solubility product constant expression for CaCO3 is Ksp = [Ca2+][CO32–]. Since equal quantities of Ca2+(aq) and CO32–(aq) are produced when CaCO3 dissolves, this expression reduces to 4.9 × 10–9 = x2, or 49 × 10–10 = x2.
141
An inflatable cuff was used to temporarily stop blood flow in an upper arm artery. While releasing the pressure to deflate the cuff, a stethoscope was used to listen to blood flow in the forearm. The blood pressure reading was 130/85. Given this information, which of the following statements is LEAST likely to be true?
A.85 mmHg was the diastolic pressure.
B.Blood flow was heard when the pressure of the cuff was greater than 130 mmHg.
C.130 mmHg was the systolic pressure.
D.Blood flow was heard when the pressure of the cuff was 90 mmHg.
The answer to this question is B because the question indicates that the cuff was inflated to temporarily stop blood flow in the artery. The systolic pressure is determined from the first sound of blood flow that can be heard once the pressure exerted by the inflatable cuff falls below the pressure in the artery. The blood pressure reading was 130/85, which indicates that blood flow started again when the pressure was 130 mmHg. Therefore, blood flow was not heard when the pressure of the cuff was greater than 130 mmHg. A is not the correct response because the lower number of the blood pressure reading represents the diastolic pressure. C is not the correct response because the higher number of the blood pressure reading represents the systolic pressure. D is not the correct response because blood flow would be heard when the pressure of the cuff is 90 mmHg, as this pressure is higher than the diastolic pressure.
142
Which single bond present in nitroglycerin is most likely the shortest?
A.C–H
B.C–O
C.C–C
D.O–N
The answer to this question is A. All of the bonds listed are single bonds. Since hydrogen has a much smaller atomic radius than second period elements, the covalent bond between C and H is shorter than any of the other bonds listed.
143
- Concave mirror: focal length ________.
| - Convex mirror: focal length _______.
Positive
Negative
144
Which of the following energy conversions best describes what takes place in a battery-powered resistive circuit when the current is flowing?
A.Electric to thermal to chemical
B.Chemical to thermal to electric
C.Electric to chemical to thermal
D.Chemical to electric to thermal
The answer to this question is D because the chemical energy of the battery elements is used as electrical energy to set the charge carriers in motion through the resistor, where they experience drag from the crystal lattice of the resistive conductor and dissipate their energy as heat from the resistor
145
Protein secondary structure is characterized by the pattern of hydrogen bonds between:
A.backbone amide protons and carbonyl oxygens.
B.backbone amide protons and side chain carbonyl oxygens.
C.side chain hydroxyl groups and backbone carbonyl oxygens.
D.side chain amide protons and backbone carbonyl oxygens.
The answer to this question is A because secondary structure is represented by repeated patterns of hydrogen bonds between the backbone amide protons and carbonyl oxygen atoms.
146
For a thermodynamic product, how do you know which one is more stable?
For a thermodynamic mixture of isomeric products, the relative mole ratio of products is directly related to the relative stability of these products. The more of one there is, the more stable it is comparatively
147
Charge of a capacitor?
| Energy of a capacitor?
q=CV
| E=1/2CV^2
148
Equation for Kw?
| What does Kw equal?
Kw=(Ka)(Kb)
| Kw=1x10^-14
149
The energy of activation for the reaction described in the passage is given by the energy of:
A.the reactants minus the energy of the products.
B.the products minus the energy of the reactants.
C.the activated complex minus the energy of the products.
D.the activated complex minus the energy of the reactants.
The answer to this question is D because the activation energy for a reaction represents the minimum energy barrier necessary to be overcome by the reactants on the path to products.
150
electric field lines are _______ spaced in a uniform field
equally
151
the formation of a peptide bond is accompanied by the formation of _____ as a by-product
water
152
Which experimental condition is NOT necessary to achieve reliable data for Michaelis–Menten enzyme kinetics?
A.Initial velocity is measured under steady state conditions.
B.Solution pH remains constant at all substrate concentrations.
C.The concentration of enzyme is lower than that of substrate.
D.The reaction is allowed to reach equilibrium before measurements are taken.
The answer to this question is D because once the reaction reaches equilibrium, measurement of Vo will be impossible and the kinetic data will look the same regardless of substrate concentration. Hence, response D is not necessary (nor desirable) to achieve reliable data for Michaelis−Menten enzyme kinetics. In contrast, Distractors A−C are essential to obtain reliable Vo versus substrate concentration data to calculate KM and Vmax using Michaelis−Menten enzyme kinetics.
153
What is the slope in a Line Weaver-Burke plot?
Km/Vmax
154
Vmax=
Vmax = Kcat[Enzyme]
155
What is the basic unit of a porphyrin ring?
The basic unit of a porphyrin is the pyrrole ring, a five-sided heterocycle containing one nitrogen atom.
156
Resistivity is the ______ of conductivity?
Inverse
157
the ______ of a wave is not affected by the medium through which it propagates.
frequency
158
Hz to MHZ
Hz= 1x10^-6 MHz
159
Hz to GHz
Hz=1x10^-9 GHz
160
When experiments are performed on enzymes that display traditional Michaelis–Menten kinetics, what shape does the graph of V0 versus substrate concentration [S] have?
A. A hyperbolic dependence on [S]
B. A linear dependence on [S]
C. A sigmoidal dependence on [S]
D. A parabolic dependence on [S]
The answer is A because traditional Michaelis–Menten kinetics describes a hyperbolic dependence of V0 on substrate concentration
161
Which experimental results confirm that Compound 1 is an uncompetitive inhibitor of a particular enzyme? In the presence of Compound 1:
A. the KM increases and Vmax decreases.
B. the KM decreases and Vmax increases.
C. both the KM and Vmax decrease.
D. both the KM and Vmax increase.
The answer is C because the presence of an uncompetitive inhibitor results in a lower apparent KM and Vmax of the enzymatically catalyzed reaction.
162
How do you measure the efficiency of an enzyme?
efficiency of an enzyme is measured by kcat/KM ratio
163
How do you find fundamental frequency?
f = v/(2L)
164
Positron Emission Spectroscopy (PET) imaging involves injecting a patient with a positron (anti-electron) emitting isotope. The emission of positrons occurs during:
alpha decay.
alpha absorption.
gamma absorption.
beta decay.
Beta decay is the decay in which a beta particle (electron or positron) is emitted from a heavy-atom nucleus.
165
What is the relationship between wavelength and frequency?
c = λf
166
At a given temperature, the resistance of a wire to direct current depends only on the:
voltage applied across the wire.
resistivity, length, and cross-sectional area.
inductance, length, and cross-sectional area.
resistivity, length, and capacitance.
The resistivity relation at a fixed temperature is
Resistance = Resistivity x Length/Area
Thus, B is the best answer.
