Q Bank

Question 1

Cystic fibrosis leads to abnormal Cl- and Na+ transport across certain epithelial membranes, leading to thick, viscous mucous. Mucous build-up limits the exocrine function of the pancreas, impairing digestion. Absorption of certain vitamins depends on proper pancreatic function. Which vitamin would likely be deficient in a patient with cystic fibrosis?

Answer 1

Carbohydrate and fat digestion begin in the mouth (fat digestion is minimal) with salivary amylase. Protein digestion begins in the stomach with pepsin. The majority of fat digestion occurs in the duodenum of the small intestine. Without adequate pancreatic function due to cystic fibrosis, the pancreatic lipases are not introduced in sufficient quantity to the duodenum. As a consequence, fat digestion is hindered. With malabsorption of lipids, fat soluble vitamins cannot be effectively absorbed. A, D, E, and K are the fat soluble vitamins and most likely to be deficient in a patient with cystic fibrosis

Question 2

Acetylsalicylic acid is acidic due to the presence of a carboxyl group. Which of the following probably explains why a patient taking aspirin doesn’t typically suffer from stomach pain?

Answer 2

Excess acid in the stomach will cause stomach pain. Typically, aspirin will not have this effect. The stomach is maintained at a pH of 2 due to the presence of HCl. In this acidic environment, acetylsalicylic acid will remain protonated and is minimally soluble. It is only in the small intestine when the pH becomes basic that the solubility of acetylsalicylic acid dramatically increases.

Question 3

Patients with severe acetylsalicylic acid poisoning are often given sodium bicarbonate to improve renal clearance. Which of the following could be the molar solubility of 0.1 M acetylsalicylic acid (Ka = 3 x 10-4) after the addition of bicarbonate?

Answer 3

Acetylsalicylic acid reacts with water in the following manner:

HA + H20 → H3O+ + A-

The equilibrium expression for this reaction is the following:

Ka = ([H3O+][A-])/[HA]

An amount ‘x’ is lost by HA (0.1 -x) and gained by H3O+ and A-. Substituting in these values gives the expression:

3 x 10-4 = x2/(0.1-x).

Because the Ka is so small, simplify the expression.

3 x 10-4 = x2/(0.1)

Solving for x (molar solubility), we determine that it is around 5.5 x 10-2.

The addition of bicarbonate will increase the solubility of acetylsalicylic acid (by removing H+ from the product side of the equilibrium reaction).

Question 4

Gain Loss Theory of Attraction

Answer 4

The “gain-loss theory of attraction” states that if an individual believes that he or she gave a negative first impression to a stranger, but then wins them over, all other things equal, the individual will be more attracted to the stranger

Question 5

Reliable Study

Answer 5

In order for a study to be very reliable, it must produce consistent results.

Question 6

Aggression is probably linked to what part of the brain?

Answer 6

Since fear registers in the amygdala, it is likely that aggression does as well. In addition, the amygdala is part of the limbic system of the brain which is heavily involved in emotion.

Question 7

In- Group Bias

Answer 7

In-Group bias is the tendency to see those in one’s own social group in a more positive light than those in any other group.

Question 8

What is the most likely psychological justification for prescribing disulfram to an alcoholic patient?

Answer 8

The goal of disulfiram administration, which is described in the first passage as causing hangover like symptoms, is to reduce alcohol consumption. These unpleasant symptoms serve as an aversive effect following administration of alcohol. Adding an unpleasant result when presented with a stimulus is an example of punishment.

Question 9

The circulatory system is a closed system with two pumps, the left side of the heart and the right side of the heart. Neglecting volume lost to the lymphatic system, which side of the heart pumps a greater volume of blood?

Answer 9

Both sides of the heart pump equal volumes of blood in healthy individuals.

Question 10

A blood sample undergoes a temperature change such that all of its thermal energy is converted to potential energy. Which of the following best describes its final state?

Answer 10

A substance at absolute zero displays no kinetic (thermal) energy

Question 11

If plaque buildup decreased an artery’s diameter by half, what effect would this have on the average kinetic energy of blood passing through the vessel, as compared to an identically-sized vessel its normal physiologic state? (Assume cardiac output is 5 L/min in both cases, and that both vessels have negligible compliance.

Answer 11

In major arteries, it is reasonable to assume that there will be no significant leakage through the endothelium. Therefore the continuity equation (V1A1= V2A2) which states that the velocity of the fluid is inversely proportional to the cross sectional area holds true. This means the velocity is inversely proportional to the square of the radius (πr2 is the cross sectional area for a circular pipe). This gives v ∝ 1/r2. If the diameter is halved, then so is the radius, v ∝ 1/(1/2r)2 which simplifies to v ∝ 4r. Therefore the velocity of the fluid in the narrowed region is four times that of the fluid before the narrowed region. To get kinetic energy use KE = 1/2(ρVv2) where ρ is the density of the fluid and V is the volume and v is the velocity. This equation shows that the kinetic energy is proportional to v2. Thus, KE ∝ (4v)2 or KE ∝ 16v2. So the kinetic energy of the fluid within the narrowed region is 16 times greater than that of the fluid just before the narrowed region

Question 12

possible explanation for why vascular flutter occurs?

Answer 12

The continuity equation shows that the velocity of a fluid in inversely proportional to the cross sectional area. So as the artery narrows the velocity of the fluid increases. Bernoulli’s equation states that when the velocity of a fluid increases, the pressure it exerts on its surroundings decreases. When the blood reaches a certain velocity due to the narrowing of the artery, the pressure on the outside of the artery becomes greater than the pressure exerted by the blood inside the artery and the walls of the artery collapse in on themselves. This stops the blood flow and then the walls snap back open. The blood then reenters the region and when it reaches the same velocity as before the walls close once again and the cycle repeats

Question 13

What is the average combined mass of cellular structures, proteins, and other solutes in a 20 ml sample of human blood if the specific gravity of human blood is 1.06?

Answer 13

Specific gravity is the ratio of the density of the fluid of interest to pure water. SG = ρfluid/ρwater. The density of water is 1 g/ml. Since 1.06 = ρblood/ 1g/ml this means that ρblood = 1.06 g/ml. Comparing the density of pure water to that of whole blood shows that 0.06 g/ml or 60 mg/ml of the blood is not from water. This must be from the cells, proteins and other solutes. To solve for the combined mass of these solutes in 20 ml of blood use 60 mg/ml x 20 ml = 1200 mg or 1.2 g. Alternatively, calculate the mass of 20 ml of pure water, 1 g/ml x 20 ml = 20 g and compare it to the mass of 20 ml of whole blood, 1.06 g/ml x 20 ml = 21.2 g; 21.2 g – 20 g = 1.2 g.

Question 14

The amount of work the heart does in one minute if the cardiac output is 6 L/min and the mean arterial pressure is 1.24 x 104 N/m2 is

Answer 14

Work = ΔV x P, where V is volume and P is pressure. Thus, work (joules) can have the units of volume x pressure. Power is work (joules)/time so power can have the units of (volume x pressure)/time. Looking back to the question stem, multiplying the cardiac output by the mean arterial pressure will give an answer that has the units of (volume x pressure)/time.

6 L/min x 1000 mL/L x 1 min/60s = 100 mL/s

Which is the same as 100 cm3/s. Looking at the unit of pressure, we see we need to change cm3 to m3.

100 cm3/s x 1 m3/106 cm3 = 1x 10-4 m3/s.

Now multiply this form of the cardiac output by the pressure.

1.0 x 10-4 m3/s x (1.24 x 104 N/m2) = 1.24 (N x m)/s = 1.24 J/s = 1.24 W

The question now asks for the work done in one minute so we get:

1.24 W x 60 s = 74.4 J.

Question 15

What range of frequencies is most likely to be used for ultrasound investigation of a pregnancy?

Answer 15

Ultrasound uses frequencies higher than human hearing. Humans can perceive sounds in the range of 20 to 20,000 Hz. This means that ultrasound should be above these values

Question 16

The learning theory

Answer 16

posits that attitudes and behaviors are developed through learning, which can be controlled through exposure and conditioning.

Question 17

The functional attitudes theory

Answer 17

functional attitudes theory states that there are four functional areas of attitudes that serve individuals in life: knowledge, ego expression, adaptability, and ego defense.

Question 18

social cognitive theory

Answer 18

states that attitudes are formed through observation of behavior, personal factors, and environment.

Question 19

elaboration likelihood model

Answer 19

states that attitudes are formed and changed through different routes of information processing based on the degree of elaboration

Question 20

The man has memory of a previously traumatic event. When he sees a spider, the similar event results in feelings of anxiety due to the implicit memory of the childhood experience. Implicit memory is controlled by the amygdala

Answer 20

explicit memory of an event is the conscious memory of the experience. This type of memory is controlled by the hippocampus.

Question 21

amygdala and parahippocampal gyrus. These structures are both part of the limbic system, which lie within the forebrain. The dorsomedial prefrontal cortex and anterior cingulate cortex also lie within the forebrain.

Answer 21

midbrain consists of the inferior and superior colliculli.

hindbrain consists of the cerebellum, medulla oblongata, and reticular formation.

Question 22

The oxygen-evolving reaction Ca(OCl)2 (s) → CaCl2 (s) + O2 (g) is initiated with 71 g of Ca(OCl)2 in a 5.5 L sealed chamber with an unknown amount of inert gas. If the resulting oxygen evolved increases the pressure of the chamber by 20%, how many moles of gas were in the chamber initially? Assume all gases are ideal and the temperature of the reaction remains constant.

Answer 22

This question appears to be asking about many things at once, so let’s break it down step by step. First, it’s not helpful to work with mass of starting reactant when we’ll need moles later on, so let’s convert that. We find the molecular weight of Ca(OCl)2 is 143 g/mol meaning we start the reaction with roughly 0.5 moles. The oxygen evolved is in a 1:1 ratio, so we know we also produce 0.5 moles of oxygen. The question then essentially relies on answering the following question: if 0.5 moles of gas increase the pressure by 20%, how much was there to start? This is a ratio problem, not a chemistry problem, and can be solved by simply dividing 0.5 by 20% (or 0.2) which gives us 2.5. Said another way: 3 (0.5 + 2.5) is 20% greater 2.5. Therefore the beginning number of moles must have been 2.5 or (B).

Question 23

Which of the following are responsible for the hardening of arteries (atherosclerosis)

Answer 23

LDL, or low-density lipoproteins, are protein-lipid assemblies used in the transport of lipids through the body through blood vessels. Low-density lipoproteins have a higher concentration of lipids than proteins (vice versa for high-density lipoproteins) and contribute to plaque building up on the walls of blood vessels. Erythrocytes are red blood cells. Gastrin is a large, peptide hormone that regulates the secretion of HCl from the parietal cells of the stomach.

Question 24

What is the molecular geometry of the ion AlCl63-

Answer 24

The optimal distribution of 6 substituent groups (and no lone pairs) would be along each axis (x, y, and z); there are four groups on a plane, one up, and one down. This way, all groups are 90° from each other. This means the ion would be octahedral.

Question 25

Transferring a protein from a 1 M electrolyte solution to a 0.1 M electrolyte solution would most likely have which of the following consequences for the protein?

Answer 25

Reducing the ion content of the buffer effectively eliminates the ability of the buffer to stabilize charges on residues (e.g. -COO-Na+). This would cause a reduction in the stability of charged species in solution, resulting in protonation of acidic residues and the deprotonation of basic residues. These two events together neutralize the charges on the compounds in accord with the decreased stability of charges in the new solution.

Question 26

A researcher wishes to conduct an experiment on classical conditioning in rats. Which of the following must happen in the experiment?

Answer 26

Classical conditioning works by pairing neutral stimuli with an unconditioned stimuli, so that during conditioning the neutral stimuli becomes the conditioned stimuli and produces a conditioned response.

Question 27

A ball of weight 20N sits at the bottom of a 100m pool. Buoyancy force is calculated and is determined to be 30N. Approximately how long will it take for the ball to rise to the surface?

Answer 27

We first need to calculate the mass of the object. We know that weight is 20N, which is equal to ma, with a=9.8 m/s2, thus mass is approximately 2 kg. We can calculate the net force, which is 10N in the upward direction. From this, we know F=ma, thus 10N = 2a, thus acceleration is 5 m/s2. Because initial velocity is zero, we can use the kinematics equation d=at2/2, thus 100 = 5t2/2. Thus t2=40, thus t is approximately 6 seconds. Thus (B) is the correct answer.

Question 28

Terminal Velocity of an Object

Answer 28

Terminal velocity is the speed at which an object experiences zero acceleration through the medium in which it is moving whereby the restraining force is generated solely by the medium itself. For example, a free-falling object will reach terminal velocity once the drag force of the air is equal to the gravitation pull of the earth. Once the two are in equilibrium, the object will cease to accelerate due to the canceling of the two forces.

Question 29

You are given the following reaction:
A + 2B → C

Three experiments were done to determine the rate law for this reaction. The following results were obtained:
Trial 1: [A] = 0.1, [B] = 0.05, Initial Rate = 1 x 10-4
Trial 2: [A] = 0.1, [B] = 0.1, Initial Rate = 2 x 10-4
Trial 3: [A] = 0.2, [B] = 0.1, Initial Rate = 5 x 10-5

What is the rate law for this reaction?

Answer 29

To solve rate law problems in a systematic fashion by comparing two experiment trials in which the concentration of one reactant is held constant. This can be repeated again to determine the rate law of the other reactant. Thus in this problem, we can first compare trials 1 and 2 since [A] is the same. We see that when [B] doubles from 0.05 to 0.1 M, the rate also doubles. Thus, the rate law for B is 1. Comparing trials 2 and 3 (since [B] is the same), we see that if [A] doubles from 0.1 to 0.2 M, then the rate decreases by a factor of 4. This means the rate law for A is -2. Hence, the rate law is Rate = [A]-2[B]

Question 30

During vacuum distillation, what is the purpose of decreasing the pressure?

Answer 30

Decreasing the pressure of a system decreases the boiling point. This in turn speeds up the distillation and eliminates the need for higher temperatures.

Question 31

Gene duplication events are common drivers of increasing complexity in organisms. How might selective pressures on such genes be different from the selective pressures on the original gene?

Answer 31

Suppose no gene duplication event occurs and the gene is mutated. Selective pressures are more likely to eliminate a deleterious mutation because the organism has few or no backups and thus the mutation will negatively affect the survival of the organism. Conversely, if a gene is duplicated and subsequently mutated, the original gene is still present to confer the proper function. Mutation of the duplicated gene would be less pressured to retain its sequence because the organism has a backup gene just in case the duplicated gene receives a deleterious mutation. Thus the selective pressures on duplicated genes are weaker

Question 32

√ 3 =

Answer 32

1.7320508

Question 33

√ 2 =

Answer 33

1.4142136

Question 34

A 70kg person is walking on slippery ice. As the person takes a step, their leg extends 30° from normal, and their entire weight shifts onto the leg. What is the minimum coefficient of friction required for the ice to not let the person slip?

Answer 34

The person weighs 700 N, which is equal to mg. As they take a step and shift all their weight, their leg is extended 30° Drawing the free-body diagram, we see that if the vertical component (mg) is 700 N, then the horizontal component (placed onto the ice for the frictional force) is 700 x 1/√3 or roughly 400 N. This can go directly into the friction equation F = μsN where N = mg = 700 N. We know F (the force placed by the foot) is 400 N, so 400 = μs700 and therefore μs = 400/700 = 0.57.

Question 35

Reaction 1: A → B + C
Reaction 2: 2B + D → E

A scientist is determining the order of a reaction. The reaction is composed of two elementary reactions as shown above. If Reaction 1 is slower than Reaction 2, what is the order of the overall reaction?

Answer 35

Because we are told Reactions 1 and 2 are elementary, we can write the rate laws using the coefficients of the reactions. For Reaction 1, the rate law would be Rate = k[A]1. Since we know it is the slower reaction, i.e. the rate-determining step, the overall reaction will have the same rate law. This makes the overall reaction first order.

Question 36

A tank launches a rocket at a 30 degree angle. It takes a total of 20 seconds for the rocket to reach the ground from being launched. The horizontal component of velocity of rocket (when launched) is 30 m/s. Approximately how far did the rocket travel horizontally when the rocket is at maximal height?

Answer 36

We are asked to find out when the rocket is at maximal height. We know that the rocket hits the ground at 20 seconds, and we can simply draw the parabola of motion to determine that the maximal height should occur at 10 seconds. The horizontal component to velocity will not change, therefore we have 30 m/s * 10 seconds = 300 m

Question 37

would be affected by a mutation in the actin protein?

Answer 37

The mitotic spindle is mediated in part by actin which helps to control the spindle’s length, supporting the microtubules. Muscle contraction is mediated by both myosin and actin. Cellular shape is largely determined by the cytoskeleton whose primary component is actin. Therefore all three will be affected by changes to actin.

Question 38

A krypton fluoride laser can emit light in brief pulses of only 4 nanoseconds. Given the velocity of light in a vacuum is 3 x 108 m/s, how long is each pulse of light if emitted underwater? Note the index of refraction of water is 1.33.

Answer 38

Let’s first unpack the reference to the index of refraction and water. The index of refraction is a ratio of the speed of light in a vacuum over the speed of light in a medium. So we know 1.33 = 4/3 = 3 x 108/v. Therefore v = 9/4 x 108 m/s in water.

Next, the pulse is 4 nanoseconds long, so 4 x 10-9 s. Therefore our d = vt equation gets d = (9/4 x 108)(4 x 10-9) = 9 x 10-1 m = 0.9 m = 90 cm.

Question 39

A string 25 cm long is fixed at both ends on an instrument. If the speed of sound is 350 m/s, what is the fundamental frequency of the sound?

Answer 39

The fundamental frequency is the longest wavelength that can be generated by a device. This is given by L = λ/2. In order to solve for the frequency, we’ll need to substitute the equation v = fλ or λ = v/f. Once substituted, we get L = v/2f which can be arranged to f = v/2L. Plugging in the variables supplied, we get f = (350 m/s)/(2 x 0.25 m) = 700 Hz.

Question 40

In order to double the period of a pendulum, one would have to:

Answer 40

For a pendulum, the period is proportional to the square root of L/g, where L is the length and g is the gravitational constant. To double the period, one would have to quadruple the length,

Question 41

N resistors which have the resistance X are all connected in parallel and resistance is measured. This resistance comes out to R. What would the resistance be if these resistors were connected in series?

Answer 41

We know that resistors in parallel add in the inverse direction. So 1/R = 1/X + 1/X + … 1/X = N*1/X. We see 1/R = N/X, thus X = N×R (meaning each resistor has resistance of NR). If we were to connect N of these in series, we would have a new resistance of NR + NR + … + NR (where there are N terms in the addition). This is equal to N × (NR) = N2R

Question 42

A wave has a frequency of 7x107 Hz and a speed of 2x109 m/s. What is the approximate wavelength of this wave?

Answer 42

We know that velocity is wavelength multiplied by frequency. Thus wavelength is 2x109/7x107 which is approximately equal to some number around 30. This is in meters, which equates to 3000 centimeters. Thus (C) is correct.

Question 43

Electronegativity is best described as:

Answer 43

Electronegativity is the tendency of an atom to attract electrons. Unequal sharing of electrons (usually between atoms far apart from each other on the Periodic Table) results in a polar covalent bond. Very large differences in electronegativity may indicate complete electron transfer, which indicates an ionic bond.

Question 44

0.5kg projectile is launched 30° to the horizontal at 40 m/s. What is its total kinetic energy at the highest point of its path? Assume air resistance is negligible.

Answer 44

Although its kinetic energy is constantly changing throughout flight, at its highest point, it has no vertical motion (only horizontal) and thus we only need to worry about its horizontal velocity. For objects in projectile motion, horizontal velocity remains constant throughout fight (when air resistance is ignored). The horizontal velocity can be calculated here as (40√3)/2 = 20√3. Using the mass and the velocity, we can now calculate the kinetic energy: (1/2)(0.5 kg)(20√3)2 = 300 J.

Question 45

In which of the following populations is the recessive phenotype more abundant than the dominant phenotype, where p represents the dominant allele and q represents the recessive allele?

Answer 45

Using allele frequencies p and q we can calculate the abundance of the recessive phenotype (homozygous recessive). The Hardy-Weinberg equilibrium equation indicates that q2 corresponds to the frequency of homozygous recessive genotypes. If q = 0.6, only 36% of the population is homozygous recessive. If q = 0.7, only 49% of the population is homozygous recessive. However, if q = 0.8, 64% of the population (therefore more abundant) is homozygous recessive.