aamc missed questions
If chromosomal duplication before tetrad formation occurred twice during spermatogenesis, while the other steps of meiosis proceeded normally, which of the following would result from a single spermatocyte?
If all other steps occur normally, then four sperm would be produced. Because replication occurred twice instead of once prior to tetrad formation, each sperm would have twice the normal amount of DNA. As a result, four diploid sperm would be produced instead of four haploid sperm.
A student performs an experiment to determine the distance moved and velocity of a projectile as a function of time. A 1.00-kg object is initially at rest. The student applies a force of 19.6 N through a distance of 0.50 m to propel the object straight upward. It has an initial speed v and reaches a peak height h above the launch point. The projectile contains a small speaker that emits a sound at a frequency of 170 Hz. The sound is detected by a microphone and recording device located on the ground directly beneath the vertical trajectory of the projectile. The recorded data are used to compute the velocity of the object using the Doppler effect. (The acceleration due to gravity at the surface of Earth is 9.80 m/s2. Air resistance may be neglected. The speed of sound in air is 340 m/s.) How much work is done in launching the object?
In a one-dimensional problem such as this, work is force times distance. Hence, (19.6 N)(0.5 m) = 9.8 J.
Ag+ + e- → AgEo = +0.80 V Cu+ + e- → CuEo = +0.52 V Pb2+ + 2 e- → PbEo = -0.13 V Zn2+ + 2 e- → ZnEo = -0.76 V With which of the above metals can copper form a galvanic cell in which copper is reduced?
In order for an oxidation-reduction reaction to proceed spontaneously, the cell potential Ecell° for the net reaction must be positive. The cell potential Ecell° can be found by subtracting the standard reduction potential Ered° for the substance being oxidized from that of the substance being reduced. therefore: lead and zinc can be used since subtracting their potentials from Cu would lead to a overall positive reduction potentials
Cholera is an acute, diarrheal disease caused by infection of the intestine with the gram-negative, motile bacterium Vibrio cholerae. After colonizing the small intestine, V. cholerae secretes cholera toxin (CTX), a protein that ribosylates the Gsα subunit of a G protein, thereby inhibiting its GTPase activity. This causes the dysregulation of a cellular chloride ion channel, resulting in efflux of ions and water from the infected enterocytes into the intestinal lumen. Studies have implicated sodium bioenergetics in the pathogenesis of V. cholerae in humans. An electrochemical gradient of Na+ known as the "sodium motive force" provides V. cholerae with the energy for key functions. The gradient is predominantly established by the Na+-pumping NADH:quinone oxidoreductase (Na+-NQR) enzyme. Na+-NQR is a multi-substrate enzyme comprised of six distinct subunits designated A-F (Table 1) that are encoded within the same operon. In a process similar to proton pumping by Complex I of the electron transport chain, Na+-NQR couples the movement of electrons from an NADH donor with ion transport. What is the most likely effect of adding a sodium ionophore to a culture of V. cholerae?
Ionophores are compounds that bind to ions and facilitate their movements across membranes. A sodium ionophore would collapse the sodium gradient (sodium motive force) that is established by the action of Na+-NQR, resulting in decreased production of ATP. answer: decreased ATP production
Which biochemical technique requires a pH gradient?
Isoelectric focusing
Which of the following best describes the movement of an electron after it is ejected from the cathode?
It accelerates towards the anode A charged particle accelerates in an electric field. The electron starts with a velocity that increases as it approaches the anode through the vacuum.
Which enzymatic kinetic parameter is NOT affected by the presence of an uncompetitive inhibitor?
Km/Vmax
If the 25 μF capacitor in the defibrillator in Figure 1 is replaced with a 30 μF capacitor, what new power supply setting would produce the same amount of charge? the volts is 3000 V for the original capacitor
On the 25 μF capacitor, the power supply stores a charge of 25 μF × 3000 V = 75 mC. On the 30 μF capacitor, the same charge is stored by a power supply that has a voltage of 75 mC/30 μF = 2500 V can also do: C1 * V1 = C2 *V2
What does NaBH4 do?
Reduces ketones and aldehydes to alcohols. Does not react with carboxylic acids, esters, or amides. But at *room temperature* it only reduces acyl chlorides to alcohols, due to the extreme electrophilicity.
What is gas-liquid chromatography?
Separation technique that uses an inert gas as the mobile phase and liquid as the stationary phase. Volatile molecules have lower bp so spend more time in the gas phase and move faster while higher BP molecules spend more time in stationary phase and move slower
An unknown solid weighs 31.6 N. When submerged in water, its apparent weight is 19.8 N. What is the specific gravity of the unknown sample?
The buoyant force on the solid is the difference between its weight (31.6 N) and its apparent weight in water (19.8 N). This force equals the weight of the water displaced, which, in turn, equals the product of the volume of the solid and the density of water. The specific gravity of the solid, i.e., the ratio of its weight to the weight of an equal volume of water, is then: 31.6/(31.6 -19.8) = 2.68.
What cells are involved in innate immunity?
The cells responsible for this response include neutrophils, macrophages, dendritic cells (DC), natural killer (NK) cells, and intraepithelial lymphocytes.
A 47-kg child with a 3-kg sled and a 54-kg child with a 6-kg toboggan slide down the ice-covered hill illustrated in the figure below. Points A and B are at the top and bottom of the hill, respectively, and are a distance l apart along the slope. Between points A and B the sled and rider slide free of friction, but the toboggan and rider are opposed by a constant 60-N frictional force. To the right of Point B the sled and rider are opposed by a 50-N frictional force, and the toboggan and rider are opposed by a 120-N frictional force. (Note: Assume that air resistance is negligible. Use g = 10 m/s2.) What is the coefficient of friction between the sled and the ground when the sled and rider are to the right of Point B?
The coefficient of friction is defined as the frictional force divided by the normal force. In this case, the frictional force is given as 50 N. The normal force on a level surface is the product of the mass and the gravitational acceleration, g. The dimensionless coefficient in the case described is 50 N/(50 kg × 10 m/s2) = 0.1
What does the dissociation constant (Kd) represent?
The concentration of ligand required for 50% of ligands to be bound
If the energy of a photon is doubled, which of the following properties of the photon will also double?
The energy of a photon is given by the relationship E = hf. If E is doubled, then frequency f is doubled, too, as Planck's constant h does not change.
Consecutive resonances occur at wavelengths of 8 m and 4.8 m in an organ pipe closed at one end. What is the length of the organ pipe? (Note: Resonances occur at L = nλ/ 4, where L is the pipe length, λ is the wavelength, and n = 1, 3, 5,...)
The examinee is given two wavelengths (8 m and 4.8 m) that yield resonance in an organ pipe closed at one end. From this information the examinee must determine the length of the pipe. The question reminds the examinee that the resonant wavelengths λ are related to the length of this pipe via: L = nλ /4, where n = 1, 3, 5... Since n increases from n to n + 2 for two consecutive wavelengths one may write for the two given wavelengths, 4L = n(8 m) and 4L = (n + 2)(4.8 m). Equating the right sides of these two equations: n(8 m) = (n + 2)(4.8 m) which is easily solved to show that n = 3. Putting n = 3 into 4L = n(8 m) yields 4L = 24 m, so L = 6.0 m
If the defibrillator described in the passage were fully charged and the entire charge were discharged through a patient in 10 ms, which of the following is closest to the average electrical current that would flow through the paddles? charge = 25 microfarads volts = 3000 V
The full charge of the capacitor is 25 μF × 3000 V = 75 mC. The average discharge current is (75 mC)/(10 ms) = 7.5 A.
The mineral component of human bone is a salt that consists primarily of all of the following EXCEPT: A. calcium B. Potassium C. Phosphate D. hydroxyl groups
The inorganic component of bone consists of submicroscopic deposits of calcium phosphate similar to hydroxyapatite (Ca10[PO4]6[OH]2), so it would be expected to contain calcium, phosphate and hydroxyl groups. The correct answer is potassium
The following reaction occurs spontaneously. Cd(s) + 2 H+(aq) → Cd2+(aq) + H2(g) Which of the following has the highest electron affinity?
The reaction equation shows the reduction of H+ by Cd. Because the H+ accepts the electron readily from Cd, it can be determined that H+ has the highest electron affinity.
An astronomer observes a hydrogen line in the spectrum of a star. The wavelength of hydrogen in the laboratory is 6.563 x 10-7m, but the wavelength in the star's light is measured at 6.56186 x 10-7m. Which of the following explains this discrepancy?
The star is approaching earth The wavelength of the light detected from the star is smaller than the laboratory value on Earth. This implies a Doppler shift (a blue shift) associated with approaching relative velocity between the star and the Earth.
What is southern blotting used for?
To detect the presence of specific sequences within a heterogenous sample of DNA, and then isolate. ***DNA***
Suppose that an extract from a muscle cell contains only the following: all the enzymes of the glycolytic pathway, including the enzyme that converts pyruvate to lactate; phosphate and other salts; NAD+ and ADP. When the extract is incubated anaerobically and glucose is introduced, neither pyruvate nor lactate is produced. What must be added in order for pyruvate to be made? options: A. O2 B. ATP C. NAD D. acetyl CoA
TP must be added. The overall glycolytic pathway yields two ATP molecules, but in order to gain these two ATP molecules by the end of the process, some ATP must be consumed at the beginning. The first reaction, the phosphorylation of glucose, for instance, requires ATP. If this is lacking in the reaction mixture, glycolysis will not be initiated. Once initiated with a small amount of ATP, however, more ATP is produced and the reaction will become self-sufficient. Therefore, the correct answer is option B. Oxygen and acetyl-coenzyme A are needed only for oxidative metabolism, so options A and D are incorrect. NAD is supplied and the process will produce NADH, but NADH is not needed for the reaction sequence to proceed, so option C is incorrect
What is the Bose-Einstein principle?
a collection of atoms cooled close to absolute zero will coalesce into a single quantum state.
the conjugate acid of a weak base is
a strong acid
the conjugate acid of a strong base is
a weak acid
the conjugate base of a strong acid is
a weak base
How to calculate pressure of a liquid in a container?
p = liquid density * acceleration due to gravity * height
When a weak acid (HA) is titrated with sodium hydroxide in the presence of an indicator (HIn), the pH at which a color change is observed depends on the:
pKa of HIn
What cells secrete glucagon?
pancreatic alpha cells
What cells secrete insulin?
pancreatic beta cells
Photoelectric detectors, by contrast, contain a light-emitting diode that sends a beam of unpolarized light across a small chamber. The light beam usually has a wavelength of 6.0 × 10-7 m and has an intensity of 1.0 × 10-3 W. When smoke particles enter the chamber, the light scatters in all directions. A photocell then senses either the increase in the scattered light or the reduced intensity of the light beam and sets off the alarm. The speed of light in air is 3.0 × 108 m/s. The frequency of the light used in photodiode detectors is:
speed of light = wavelength * frequency frequency = speed of light / wavelength (3.0 x 10^8) / (6.0 * 10^-7) = 5 x 10^14 Hz
the conjugate base of a weak acid is
strong base
Which carbon in an amino acid is chiral?
the alpha carbon (except for glycine)
Which event occurs when a G protein-coupled receptor is activated?
the alpha subunit binds GTP
In order to determine the relative speed of approach of a sound source by Doppler measurements, three of the following items of data are necessary. Which one is NOT required?
the distance between the source and the observer Given that v is the speed of sound in the medium, the Doppler equation for a source that is approaching (receding from) an observer can be written as
A 47-kg child with a 3-kg sled and a 54-kg child with a 6-kg toboggan slide down the ice-covered hill illustrated in the figure below. Points A and B are at the top and bottom of the hill, respectively, and are a distance l apart along the slope. Between points A and B the sled and rider slide free of friction, but the toboggan and rider are opposed by a constant 60-N frictional force. To the right of Point B the sled and rider are opposed by a 50-N frictional force, and the toboggan and rider are opposed by a 120-N frictional force. (Note: Assume that air resistance is negligible. Use g = 10 m/s2.) The sled and rider start from a location on the hill that is 10 m lower than Point A. How does the speed of the sled and rider at Point B, starting from this location, compare to the speed of the sled and rider at Point B when starting from the top of the hill?
he sled and rider are free of friction sliding down the hill. Equating the loss of potential energy (mgh) to the gain of kinetic energy (mv2/2), the ratio of speeds at the bottom of the hill when starting at h = 10 m and at h = 20 m is: v210/v220 = 10/20. Taking the square root gives: v10/v20 = (1/2)^1/2 or v10 is slower than v20 by a factor of 2^1/2
What type of response is mediated by B cells?
humoral
What is the pH of the equivalence point in any titration?
the pH of the salt solution formed
What reaction is catalyzed by NADH ubiquinone oxioreductase?
the two-electron reduction of a ketone to an alcohol
Electric power for transmission over long distances is "stepped up" to a very high voltage in order:
to cut down on the heat loss in the transmission wires
Photoelectric detectors, by contrast, contain a light-emitting diode that sends a beam of unpolarized light across a small chamber. The light beam usually has a wavelength of 6.0 × 10-7 m and has an intensity of 1.0 × 10-3 W. When smoke particles enter the chamber, the light scatters in all directions. A photocell then senses either the increase in the scattered light or the reduced intensity of the light beam and sets off the alarm. The speed of light in air is 3.0 × 108 m/s. Destructive interference occurs in photodiode detectors when direct and scattered light rays take paths to the photocell that differ in phase by:
180 degrees The phase difference corresponding to a half of a wave is 180°. Half a wave difference in phase between two waves corresponds to destructive interference
How many cm^3 are in 1 L?
1L = 1000 cm^3
A 0.5-kg uniform meter stick is suspended by a single string at the 30-cm mark. A 0.2-kg mass hangs at the 80 cm mark. What mass hung at the 10-cm mark will produce equilibrium?
1kg you set it up like as m1v1 = m2v2, but you have to add the two forces: (0.5kg ruler cm * g * 20cm ) + (0.2kg * g * 50cm) = x * g * 20cm -20cm is the difference of (center of mass - string location) = 50cm -30cm -g is acceleration due to gravity (need force to do this equation)
The fundamental, resonant wavelength of a pipe open at both ends that is 1 m long and 0.1 m in diameter is:
2 m Pipes and tubes have their resonant wavelengths when standing waves develop. An open pipe has its fundamental, resonant wavelength at twice the length of the pipe. Both ends have displacement antinodes (maximum amplitudes) with a node in the middle of the pipe. Thus, the pipe is half a wavelength long. The resonant wavelength is independent of the diameter of the pipe.
Ignoring stereochemistry, how many different tripeptides may exist that contain the same three amino acids as the molecule shown below?
3! = 3 x 2 x 1 = 6
Approximately how many moles of Al3+ are reduced when 0.1 faraday of charge passes through a cell during the production of Al? (Note: Assume there is excess Al3+ available and that Al3+ is reduced to Al metal only.)
A faraday is equal to one mole of electric charge. Because each aluminum ion gains 3 electrons, 0.1 faraday of charge will reduce 0.1/3 moles of aluminum, or 0.033 moles of aluminum.
Which of the following describes the direction of the magnetic force on an ion moving in an artery past a flowmeter?
A magnetic force acts on a moving charge in a direction that is perpendicular to both the velocity of the charge and the direction of the magnetic field. This is a basic law of the interaction of electric currents and magnetic fields.
In a nearsighted individual, the image of a distant object is focused:
A nearsighted (myopic) person can focus on nearby objects but cannot clearly see objects far away. The nearsighted eye has a focal length that is shorter than it should be, so the rays from a distant object form a sharp image in front of the retina. This condition is corrected by glasses with a diverging lens.
A student has a thin copper beaker containing 100 g of a pure metal in the solid state. The metal is at 215°C, its exact melting temperature. If the student lights a Bunsen burner and holds it for a fraction of a second under the beaker, what will happen to the metal?
A small amount will turn to liquid and the temperature will remain the same Melting occurs at a constant temperature because a certain amount of energy, the latent heat of fusion, is needed to convert a substance from its solid to liquid state. The temperature of the metal will not increase above its melting point until all of the metal has melted. The small amount of heat supplied by the bunsen burner is insufficient to melt 100 g of the metal but could melt a small amount of the metal at the constant temperature of the melting point.
continuity of flow equation:
(A1)(V1) = (A2)(V2) A = area of tube (pi(r)^2) V = velocity of fluid
From Table 1, in which metabolic process are GI tract bacteria directly involved?
... converting polysaccharides into short-chain fatty acids GI tract bacteria convert monosaccharides and polysaccharides into acetate, propionate, and butyrate, which are short chain fatty acids.
An object that is totally immersed in benzene (specific gravity = 0.7) is subject to a buoyancy force of 5 N. When the same object is totally immersed in an unknown liquid, the buoyancy force is 12 N. What is the approximate specific gravity of the unknown liquid?
1.7 you make a proportion : 5/0.7 = 12/x
Students constructed the electrical circuit shown below to study capacitors. A battery with a voltage of 10 V is connected through a switch to a capacitor and a 500-Ω resistor. The capacitor is constructed from two flat metal plates, each with a surface area of 5.0 × 10-5 m2. The plates are separated by 1.0 × 10-3 m, and the space between the plates is a vacuum. The connecting wires have no resistance. After the switch is closed and the capacitor is fully charged, a particle with a charge of 8.0 × 10-19 C and a speed of 1.0 m/s is injected midway between the capacitor plates. Another capacitor, identical to the original, is added in series to the circuit described in the passage. Compared to the original circuit, the equivalent capacitance of the new circuit is:
1/2 as great
what equation relates distance, time, and acceleration?
1/2at^2 = d
What is the value of Kb for the conjugate base of a weak organic acid that has a pKa of 5?
10^-9 Because pKb = 14 - pKa, this is the Kb for the conjugate base of an acid with a pKa of 5.
As the pH of a solution of this amino acid is raised, which group deprotonates first?
As the pH is raised, the most acidic group deprotonates first. Of the choices, two are carboxylic acids, one is a hydroxyl group, and one is a protonated amine. The hydroxyl group is least acidic, while the protonated amine is less acidic (pKa ~ 10) than a carboxylic acid group (pKa ~ 5). Of the two carboxylic acid groups, the one next to the chlorine atoms will be more acidic since its conjugate base (an anion) will be stabilized by an inductive effect which dissipates negative charge building up.
Which ligand has a higher affinity if the Kd is 2 for A and 1 for B?
B because a lower Kd (dissociation constant) means a higher affinity
What cells are involved in adaptive immunity?
B cells and T cells aka: lymphocytes and monocytes
Suppose that a stream of fluid flows steadily through a horizontal pipe of varying cross-sectional diameter. Neglecting viscosity, where is the fluid pressure greatest?
Bernoulli's equation for horizontal fluid flow (when viscosity is neglected) states that the pressure plus kinetic energy density of the fluid is constant. If the fluid velocity falls, the kinetic energy density decreases so the pressure increases. The fluid velocity is lowest where the diameter of the pipe is a maximum. Thus, the pressure is greatest where the diameter is a maximum.
What type of response is mediated by T cells?
Cell-mediated
A student performs an experiment to determine the distance moved and velocity of a projectile as a function of time. A 1.00-kg object is initially at rest. The student applies a force of 19.6 N through a distance of 0.50 m to propel the object straight upward. It has an initial speed v and reaches a peak height h above the launch point. The mathematical expression for h is:
Conservation of energy implies KEinitial = PEfinal, or mv2/2 = mgh; therefore, h = v2/2g
A 15.0-eV photon collides with and ionizes a hydrogen atom. If the atom was originally in the ground state (ionization potential =13.6 eV), what is the kinetic energy of the ejected electron?
Conservation of energy requires that the 15.0 eV photon energy first provides the ionization energy to unbind the electron, and then allows any excess energy to become the electron's kinetic energy. The kinetic energy in this case is 15.0 eV - 13.6 eV = 1.4 eV
Which of the following occurs when electrons are ejected from the cathode?
Current flows through the circuit The electrons ejected from the cathode are replaced by electrons from the battery and anode. The only effect on the apparatus of electron ejection from the cathode is the current in the circuit.
What equation for an electric field with a fixed voltage between a cathode and an anode?
E = (V − IR)/L
equation for electric field of a point charge:
E = kQ/r^2 r is distance away from point charge
Sound of a known frequency, wavelength, intensity, and speed travels through air and bounces off an imperfect reflector which is moving toward the source. Which of the following properties of the sound remains the same before and after reflection?
speed Within still air, the speed of sound remains constant
How to calculate the speed of a wave?
speed = wavelength x frequency
Why are the percentages of the change in frequency and wavelength much greater when sound waves are used instead of radio waves in these experiments?
A. Sound waves travel more slowly B. Sound waves have a much higher frequency C. Sound waves have a much shorter wavelength D. Interference in the atmosphere affects sounds waves much more The Doppler equation for frequency is Δf/f = -v/c for a given relative velocity v between source and detector. Thus, the frequency shift Δf depends inversely on the speed of the wave in the medium in which it propagates, c. The velocity of sound is much smaller than that of electromagnetic radiation, so for the same relative velocity the frequency and wavelength shifts are much greater for sound than for radio waves. Therefore A is the correct answer
If the red line in the Balmer series has a wavelength of 656 nm, which of the following is closest to its frequency?
For light that travels in vacuum, wavelength and frequency are related according to wavelength × frequency = 3.0 × 108 m/s. Solving for frequency yields (3.0 × 10^8 m/s)/(656 × 10^-9 m) = 4.6 × 10^14 Hz.
The side chain of which amino acid is most likely to form a hydrogen bond with the side chain of glutamate?
Gln
Students constructed the electrical circuit shown below to study capacitors. A battery with a voltage of 10 V is connected through a switch to a capacitor and a 500-Ω resistor. The capacitor is constructed from two flat metal plates, each with a surface area of 5.0 × 10-5 m2. The plates are separated by 1.0 × 10-3 m, and the space between the plates is a vacuum. The connecting wires have no resistance. After the switch is closed and the capacitor is fully charged, a particle with a charge of 8.0 × 10-19 C and a speed of 1.0 m/s is injected midway between the capacitor plates. Making which of the following changes to a circuit element will increase the capacitance of the capacitor described in the passage?
Increasing the surface area of the capacitor Capacitance C depends on geometric factors only, and in the case of parallel plates, C is proportional to the plate area and inversely proportional to the separation distance of the plates.
Which membrane transporter is electrogenic and translocates a net charge across the membrane?
Na+−glucose cotransporter
Equation for charge of capacitor:
Q=CV (charge equals capacitance times voltage) capacitance is in farads (F)
How are polar bodies determined in oocyte undergoes meiosis?
Unequal distribution of cytoplasm (both bodies contain same amount of nuclear material)
A heterotrimeric protein consists of three subunits with molecular weights of 10 kDa, 40 kDa, and 100 kDa. The protein is denatured with 3 M urea and subjected to size-exclusion chromatography. Which solute is the last compound to elute from the column?
Urea
Which of the following is closest to the wavelength of a photon whose energy is 2 eV? λ = hc/E, where E is the energy of the photon, h = 4.1 × 10^-15 eV•s is Planck's constant, and c = 3 × 10^8 m/s is the speed of light
Using hc = 4.1 × 10-15 eV•s × 3 × 108 m/s = 1230 eV•nm, and λ = hc/E, then E = 2 eV corresponds to λ = (1230 eV•nm)/(2 eV) = 615 nm, which is closest to 620 nm.
In an enzyme-catalyzed reaction where enzyme concentration is held constant and substrate concentration is relatively low, which kinetic parameter will increase with the addition of more substrate? (Note: Other than substrate concentration, assume no other changes to reaction conditions.)
V0
Which of the following structures is derived from the same germ cell layer as the heart?
bone
How many molecules of NADH are produced from six molecules of glucose that undergo glycolysis?
each cycle of glycolysis produces two NADH molecules and requires an input of one glucose molecule
Smoke detectors fall into two major classes. Ionization detectors, the most common units, contain two parallel electrodes that are typically separated by 3 cm with a 5-V potential difference across them. What is the magnitude of the electric field (N/C) between the two electrodes in ionization type detectors ?
electric field can be given as volts per meter (V/m) because 1 J = 1 Newton meter and 1 V = 1 J/C 5V / 0.03m = 166.6 V/m = 166.6 J/V = 166.6 N/C
Suppose that a ball is thrown vertically upward from earth with velocity v, and returns to its original height in a time t. If the value of g were reduced to g/6 (as on the moon), then t would:
factor of 6 The round-trip time t for a ball thrown vertically is given by t = 2v/g. If g is replaced by g/6, then t is increased by a factor of 6
An object with 15 grams mass is immersed in benzene and suffers an apparent loss of mass of 5 grams. What is the approximate specific gravity of the object? (Data: Specific gravity of benzene = 0.7.)
he buoyant force on an object immersed in a fluid is equal to the weight of the fluid displaced by the object (Archimedes' principle). There were 5 g of liquid displaced; thus, the ratio of object mass to fluid mass is 15/5 = 3. The specific gravity of the object (mass per unit volume compared with water) is three times the specific gravity of benzene (3 x 0.7 = 2.1) because the volumes of object and displaced liquid are equal.
An object is placed upright on the axis of a thin convex lens at a distance of four focal lengths (4f) from the center of the lens. An inverted image appears at a distance of 4/3f on the other side of the lens. What is the ratio of the height of the image to the height of the object?
he ratio of object to image distance equals the ratio of object to image height. The ratio of image to object height is found by rearranging the ratios to give (4f/3)/4f = 1/3. The image is demagnified by a factor of 3.
What is the dependent variable in an experiment that determines the Michaelis-Menten kinetic parameters of an enzyme?
initial velocity
Visible light travels more slowly through an optically dense medium than through a vacuum. A possible explanation for this could be that the light:
is absorbed and re-emitted by the atomic structure of the dense medium
When a sound source moves away from an observer, the observer has the impression that the sound source is:
lower in frequency than it actually is The question requires knowledge of the Doppler-shift phenomenon. A sound source moving away from an observer appears to have its source frequency shifted to a lower frequency when detected.
Delayed ovulation, as a cause of tubal pregnancy, would most likely be associated with delayed secretion of which of the following hormones?
lutenizing hormone progesterone is secreted in response to LH and estrogen triggers LH
Is an -OH group more polar or less polar than a corresponding carbonyl oxygen?
more polar
What is Snells law of refraction?
n1sinθ1 = n2sinθ2
A person pushes on a rolling cart with a force that diminishes with time because the person must walk faster to keep up with the accelerating cart. How much work does the person generate while pushing on the cart?
solve for area = 1/2 B * h = 1/2(100 * 20) = 1000 J
Is silica polar or non-polar?
polar
What is the purpose of boiling chips?
prevents superheating by bubble formation to break surface tension
How to determine if an image is real or virtual and whether it's upright or upside down?
real image : -forms from converging light rays and are created when objects are located outside the focal length of the converging lenses -positive focal length will indicate a convex mirror and converging lenses -positive image distance will indicate a real image (from the 1/f = 1/di + 1/do) -real images are always upside down virtual image: -forms when light rays diverge and are created when objects are located inside the focal length of the converging lenses -negative focal length will indicate a concave mirror and diverging lenses -negative image distance will indicate a virtual image -virtual images are always upright
A glass fiber carries a light digital signal long distances with a minimum loss of amplitude. What optical property of glass allows this phenomenon?
reflection
Students constructed the electrical circuit shown below to study capacitors. A battery with a voltage of 10 V is connected through a switch to a capacitor and a 500-Ω resistor. The capacitor is constructed from two flat metal plates, each with a surface area of 5.0 × 10-5 m2. The plates are separated by 1.0 × 10-3 m, and the space between the plates is a vacuum. The connecting wires have no resistance. After the switch is closed and the capacitor is fully charged, a particle with a charge of 8.0 × 10-19 C and a speed of 1.0 m/s is injected midway between the capacitor plates. If the speed of the charged particle described in the passage is increased by a factor of 2, the electrical force on the particle will:
remain the same Electrical force depends on the particle's charge and the strength of the electric field experienced by the particle, not on the particle's speed.
Specific activity is a measure of:
the enzyme units per milligram of total protein in a solution
The graphs in Figure 2 illustrate the characteristics of two adjacent tones from a bassoon. Figure 2a shows the pressure variations and the amplitudes of the harmonics for one of the tones, and Figure 2b shows the same information for the other tone. If the frequency of the first harmonic in Figure 2a is 100 Hz, what is the period of the second harmonic?
the first harmonic frequency = 100Hz 2nd harmonic frequency = 100*2 period = T = 1/f 1/200 s^-1 = 0.005s
