MCAT Test 17 (Princeton Review 2)
A certain farsighted person cannot see objects closer than 100 cm (often called the near point). What is the power of the corrective lens that will bring the near point to 25 cm?
-3D -The corrective lens would make an object that is 25 cm appear to be at 100 cm (since the eye can only see objects at a distance greater than or equal to this). Since the image is to appear on the same side of the lens as the object, the image distance must be negative. This means that in the equation 1 / o + 1 / i = 1 / f, o = 25 cm and i = -100 cm. Since lens power P = 1 / f, we see that P = 1 / (25 cm) + 1 / (-100 cm) = 1 / (0.25 m) - 1 / (1 m) = 4 D - 1 D = 3 D.
An individual action potential in a model neuron results in 100 sodium ions crossing the cell membrane. Given that the sodium-potassium pump requires a single molecule of ATP per cycle, how many acetyl-CoA would be required to generate enough energy to extrude the new sodium in the cell via the pump?
-4 -Each acetyl-CoA generates 10 ATP equivalents (3 NADH = 7.5 ATP, 1 FADH2 = 1.5 ATP, and 1 GTP = 1 ATP) and the sodium-potassium pump removes three sodium from the cell per cycle at the expense of one ATP. -A total of 34 cycles of the pump would be required to remove the 100 sodium from the cell and this would require 34 ATP. To ensure we have sufficient ATP, four acetyl-CoA are needed
Suppose the experimental apparatus is rotated 90°, such that the direction of the electric field points vertically down relative to the ground. What electric field strength will keep a negatively charged ball in static equilibrium?
-5 V/m -At equilibrium, the magnitude of the electrostatic force due to the applied field will equal the magnitude of the gravitational force. Thus qE = mg, so: E = mg / q = (10 × 10-3 kg)(10 m/s2) / (2 × 10-2 C) = 5 V/m. Note that volts per meter and newtons per coulomb are equivalent units for electric field strength.
What did Emile Durkheim believe about crime?
-A society without crime is impossible -Durkheim believed that crime is present in every society; it cannot, and should not, be eliminated
What condition would cause a sensory neuron designed to detect wind to convey the greatest amount of information at its peak firing rate?
-A windy day generating greater neuronal variability -According to the passage, the peak firing rate for a neuron conveys the greatest amount of information when there is more neuronal variability. In a neuron designed to detect wind, a windy day would generate greater variability with an inconsistent background firing rate
P. furiosus was transformed to incorporate five genes from Metallosphaera sedula, another archaeon, encoding a total of thirteen enzymes to form a cyclic process in which two molecules of carbon dioxide are fixed to form acetyl-CoA and ultimately 3-HP. When this is later consumed as fuel, the carbon dioxide that had been used to generate the molecule will be released resulting in zero net carbon dioxide emission. When plant biomass is utilized as a fuel source, the glucose subunits composing cellulose were formed from the fixation of carbon dioxide by the plant of origin. This process, commonly known as the Calvin cycle, is energetically inefficient whereas the method described here represents a significant advance in the efficiency of generating fuel from atmospheric carbon dioxide. The fixation of carbon in order to generate acetyl-CoA involves which of the following processes?
-ATP Hydrolysis -The process of carbon fixation requires a significant investment of energy to form a higher energy product
Compared to a stimulus presented at 45 degrees, which of the following is LEAST likely to have changed in duration in response to a stimulus at 0 degrees?
-Absolute refractory period -As the firing rate of a neuron increases, the absolute refractory period is least likely to change as it is a function of the inactivation of the voltage-gated sodium channels -As the rate of action potentials increases, the time between repolarizations and depolarizations will decrease, as will the relative refractory period
What is the CCA sequence in tRNA's?
-All tRNAs, regardless of the amino acid they can carry, contain a CCA sequence at their 3' end where they can be bound to an amino acid -At the 3' region of all tRNAs is a CCA (5' → 3') sequence to which an amino acid is bound by aminoacyl-tRNA synthetase
In sphingomyelin, the sphingosine is linked to a fatty acid from what type of bond?
-Amide bond
In a half cell where the right half is full of 0.5 M Cu2+ ions and the left cell is full of 1.5 M Cu2+ ions, which way will the current flow?
-The current will move right and Cu2+(aq) + 2e -> Cu (s) will occur in the left half cell -During the course of the reaction the concentration of Cu2+ in the concentrated cell decreases while the concentration of Cu2+ in the dilute cell increases. Therefore, [Cu2+] must be reduced in the left cell If reduction takes place on the left, electrons must be flowing to the left. By convention, current flows in the direction where a positive charge would flow, or the opposite direction
Where does digestion of carbohydrates and lipids occur?
-The digestion of carbohydrates and lipids starts in the mouth -Salivary amylase and lingual lipase are released along with the saliva, and therefore the digestion of carbohydrates and lipids starts in the mouth
How is the epidermis different from the dermis and hypodermis?
-The epidermis does not contain blood vessels but the dermis and hypodermis do
There are two subtypes of GSD I that are clinically recognized. GSD Ia is caused by a deficiency in the catalytic subunit of G6Pase while GSD Ib results from the malformation of a glucose-6-phosphate transporter that moves glucose-6-phosphate into the endoplasmic reticulum for hydrolysis. What would support a diagnosis of GSD Ia instead of GSD Ib?
-An increase in the endoplasmic reticulum concentration of G6P following intracellular administration of G6P -In these patients, G6P could be transported into the endoplasmic reticulum, but once inside, it could not be hydrolyzed to glucose. Thus, intracellular administration of G6P would increase the concentration of G6P in the endoplasmic reticulum
An adolescent is arrested for heroin use and prostitution. In defending herself, she claims that she was part of a group of female heroin users who used sex to obtain money. She seems to have lost her sense of identity and does not assume any responsibility for her actions. This is an example of:
-deindividuation -Deindividuation involves a loss of identity and self-awareness, which is associated with the loss of one's sense of responsibility. -This girl's feelings of anonymity and close ties with her group have led her to forget her individuality and consequently reject responsibility for her actions
In the little Albert experiment, what did Albert demonstrate overall?
-generalization -Little Albert demonstrated fear in response to objects that were not exactly the same as the object that he was conditioned with (the white rat), such as cotton balls and a white rabbit. -When organisms demonstrate the conditioned response to stimuli other than the conditioned stimulus (oftentimes these stimuli are similar in some way), this is known as generalization
DNA "melting" is the process by which double-stranded DNA (dsDNA) is separated into single-stranded DNA (ssDNA). What accounts for an increase in the UV absorption of a sample of DNA undergoing DNA melting?
-Structural changes altering conjugation across the aromatic DNA bases -UV-Vis spectroscopy is used to measure changes in light absorption in highly conjugated systems, such as in aromatic compounds. -The aromatic bases in dsDNA are tightly held in a coiled arrangement by H-bonds. When these interactions are removed in DNA melting, the chains can structurally relax. This allows changes in the conjugation of the bases, altering how much light is absorbed by a sample
Three major effects Heroin has on the body
-Symptoms of heroin withdrawal include many varied unpleased side effects, such as pain and diarrhea -Prolonged use of heroin causes a decrease in the production of endogenous opiates -Addicts become physically dependent on heroin and, over time, greater amounts of the drug are needed to produce the desired high
A simple pendulum with mass m and length L is found to have a period of oscillation T1 when the amplitude is 10°. The mass is then doubled while the length and amplitude stay the same. The period is now T2. Then the amplitude is increased to 70° while mass and length stay the same. The period is now T3. What can we say is true?
-T1=T2<T3 -For small angles, the period of a simple pendulum is given by the following equation and therefore is independent of mass. This means that T1 = T2 -Period is, to a good approximation, independent of amplitude for small angles. For large angles, however, the above equation no longer holds and the period would be noticeably different than it would be at small angles.
What is true about ATP in the pentose phosphate pathway?
-The PPP does not directly utilize or produce any molecules of ATP -Unlike many other biochemical pathways regarding glucose and glucose derivatives, the PPP does not directly utilize or produce ATP
Researchers conducted an experiment in which students who favored smoking and students who opposed smoking were placed into separate groups and asked to respond to issues about smoking, both before and after discussion with their like-minded groups. Student attitudes were measured on a scale indicating the degree to which the students favored, opposed, or were neutral about smoking before and after discussion. What prediction is most consistent with the group polarization hypothesis?
-Attitudes shared by group members will strengthen after the discussion and the initial gap in attitudes between the two groups will be increased. -Group polarization results in enhancement, or strengthening, of preexisting tendencies of the members of a group as the result of their similar attitudes. The group polarization hypothesis would predict that, after discussion within the groups, the group favoring smoking would have a strengthened attitude in support of smoking while the group opposing smoking would have a stronger opposition towards it. The strengthened positions of each group would result in a larger gap in attitudes between the two groups compared to the initial gap
Priming is best described by what?
-Awakening associations in memory, which affect the interpretation of what follows -William James described priming as the awakening of associations. Events may awaken or prime our associations without our realizing it. For example, watching a scary movie while alone can prime thinking by activating frightening memories that cause one to interpret an innocent noise as an intruder. -The subliminal images presented to the participants in the experiment discussed above acted as preconceptions, which automatically and unconsciously influenced how the individuals interpreted the final task of working with a "stranger"
A patient comes into the office complaining of difficulty sleeping, fatigue, loss of appetite, lack of interest in formerly engaging pastimes, and pervasive sadness. During the clinical interview he reveals that he is deeply in debt because of past spending sprees, during which he charged significantly more purchases on his credit card than he could afford to buy. He also reports that, during those same times, he frequently begins projects but does not complete them, and is able to go several days without sleeping. He also acknowledges that he sometimes hears voices. This patient is most likely describing which disorder?
-Bipolar I Disorder -Bipolar I disorder is generally brought to the attention of medical professionals when the patient is experiencing significant depressive symptoms. -However, questioning will reveal that the individual has also experienced manic symptoms, such as excessive spending, difficulty completing projects, decreased need for sleep, and an increase in goal-directed activities
What is the most likely explanation for the widely different types of symptoms observed in Gaucher's syndrome?
-Ceramide is ubiquitously expressed throughout the body and across organ systems -The question asks why Gaucher disease results in symptoms that affect nearly every organ system of the body. The passage indicates that ceramide is a vital ingredient in the healthy cell membrane; without this vital ingredient, cell membranes of tissues across all organ systems are deprived of a vital component and fail to form normal, functioning tissues
During which stage of cognitive development does Piaget suggest that a child will begin to understand that if he or she has milk in a glass that is short and wide, and then pours the milk directly into a glass that is tall and narrow, the amount of milk remains constant even though it appears that there is more milk in the tall glass?
-Concrete operational (ages 7 to 11) -The process of pouring liquid into different containers and understanding that the amount of liquid remains the same despite the container size or shape is called conservation, which children achieve during the concrete operational stage of cognitive development
The statement that men in our society are more capable than women are of drawing on social networks that are useful to locate employment and to rise up the "corporate ladder" most aligns with what?
-Conflict perspective -Conflict theory views societies in a framework of class conflicts and views the domination of one group by another group as an integral aspect of social order. -Since the statement focuses on inequality it aligns with the conflict perspective
What is an example of horizontal gene transfer?
-Conjugation between an Hfr and an F- bacterium -According to the passage, horizontal gene transfer is a process in which an organism incorporates genetic material from another organism without being the offspring of that organism. -Conjugation, the passing of genetic material from bacteria to bacteria via a conjugation bridge, is an example of this
Three major criterion fro major depressive disorder?
-Depressed mood -Felling of hopelessness -Insomnia or hypersomnia
Opiates stimulate the brain's mesolimbic reward system. What neurotransmitter is located in this area of the brain?
-Dopamine -The mesolimbic reward system is known as a dopaminergic pathway, which transmits dopamine throughout the brain. Dopamine is the only one of the above-mentioned neurotransmitters that can be found in the mesolimbic reward center (it can also be found in the nigrostriatal and the tuberoinfundibular pathways). -When opiates stimulate the reward pathway, an increased amount of dopamine is released
As a victim shares her side of the story with the offender, she remembers specific details about the crime and the effects that the crime has had on her life. This is an example of:
-Episodic memory -Episodic memory is associated with memories of past events
An American travels to Mozambique, where he is told that restorative justice is sometimes initiated by magamba, or spirits of dead soldiers. The traveler finds this notion absurd and unorthodox. When he returns to the United States, he speaks condescendingly of the practice. This is an example of:
-Ethnocentrism -Ethnocentrism refers to the mindset of an individual who believes that his or her own culture and way of life are superior to those of others. In the scenario described above, the individual seems believe that American customs are better than those of Mozambique
It has been shown that hydroxylation of proline in the presence of ascorbic acid dramatically increases the stability of the procollagen superstructure that comprises collagen. Which of the following likely contributes most to the added stability that results from hydroxylation?
-Stereoelectric effects -Hydroxylation of the proline functional group effectively produces an induced dipole in which the electronegative oxygen of the hydroxyl group makes the charge of the adjacent hydrogen and carbon atoms δ+; stereoelectronic effects in the form of "stacked" δ- and δ+ charges from the three inter-woven alpha helices in close proximity to one another creates a highly stable triple helix quaternary structure
Glycogen storage disease (GSD) results from a defect in the metabolic synthesis or breakdown of glycogen. There are numerous types of GSDs that are characterized by a deficient enzyme. GSD I is a type of hepatic GSD caused by a deficiency in the enzyme glucose-6-phosphatase (G6Pase). G6Pase is responsible for the hydrolysis of glucose-6-phosphate (G6P) in the lumen of the endoplasmic reticulum and plays a central role in both gluconeogenesis and glycogenolysis. Without treatment, patients typically experience increased blood levels of lipids due to amplified triglyceride production, as well as increased lactic and uric acid levels. Additional characteristics of GSD I include short stature and muscle atrophy. Pediatric patients with GSD I often present with a protruding abdomen. Which of the following best explains this finding?
-Excess hepatic glycogen stores cause the liver to enlarge and press against the abdominal wall -Deficiency in G6Pase will cause increased glycogen stores in the liver due to decreased glycogenolysis. The excess glycogen stores will increase the size of the liver, causing it to press against the abdominal wall
f lactic acid radiolabeled with carbon-11 were injected intramuscularly in a patient, where would radioactive carbon most likely be detected?
-Expired breath -Lactic acid, which dissociates to become lactate at physiological pH, is converted to acetyl-CoA in the liver before rejoining cellular respiration and ultimately being released as carbon dioxide
Suppose a child receives a highly desirable reward from his parents for every five homework assignments that he completes. What type of reward schedule is this and what impact should it have on the child's behavior?
-Fixed ratio; the child should demonstrate a high rate of response, meaning that he is likely to diligently complete his homework assignments in a fairly consistent manner in the hopes of reaching five completed assignments and obtaining his reward. -A fixed-ratio schedule provides reinforcement (in this case, a highly desirable reward) after a set number of instances of the behavior (in this case, after five completed homework assignments). -If a fixed-ratio schedule is utilized, the child should demonstrate a fairly high rate of response, meaning that he is likely to consistently complete his five homework assignments in anticipation of his reward
Glycogen is stored by the body via polymerization to form both α-1,6 and α-1,4 glycosidic bonds. Which one of the following statements would best provide evidence to support this structural feature?
-Glucose reacts with Benedict's reagent to form a red precipitate, whereas glycogen does not react. -The formation of glycosidic linkages between glucose monomers modifies the hemiacetal of glucose into an acetal. Benedict's reagent reacts with reducing sugars like glucose that contain hemiacetals to form a red precipitate, but not with non-reducing sugars that contain acetals, such as glycogen.
The stability of the collagen triple helix depends partly on the repetitive sequence of amino acids which comprise the individual alpha helices. Which of the following amino acids most likely faces the center of the collagen triple helix?
-Glycine -The most stable structure for the collagen triple helix will likely feature the amino acid with the least sterically-hindered functional group facing the center of the helix; as such, glycine, whose functional group is a mere hydrogen atom, will be most likely to face the center of a stable triple helix
Suppose that parents catch their teenage daughter stealing beer from a convenience store. If the parents want to decrease the likelihood that their daughter will steal again, what action would constitute a positive punishment to this desired end?
-Harshly rebuking their daughter upon detection of the stolen beer -Positive punishment involves applying an undesirable stimulus after a given behavior with the intent of decreasing the likelihood that the behavior (stealing) will happen again. Harshly rebuking their daughter involves the parents' applying a negative stimulus, and thus constitutes positive punishment
If an individual suffers brain damage and can no longer remember how to tie his own shoes or drive a car (though these are both skills that he mastered years ago and used daily up until the brain injury), but is able to recall what he ate for breakfast yesterday, and can describe his high school prom, wedding day, and last birthday without difficulty, what can be reasonably concluded?
-He has suffered damage that impacts his implicit memory, but his explicit memory appears intact. -If an individual can no longer remember how to complete procedural tasks, such as shoe-tying and driving, he has suffered some sort of damage to his implicit (or nondeclarative) memory system. -Since he is still capable of remembering personal events, even from years past, it appears as though his explicit (or declarative) memory remains unaffected
Three biggest things that happen during a humoral immune response?
-Immunoglobins bind to antigen -Complement activation (activated by the presence of bound antibodies on a foreign cell) -Direct inactivation of an antigen by an antibody
Glycogen storage disease (GSD) results from a defect in the metabolic synthesis or breakdown of glycogen. There are numerous types of GSDs that are characterized by a deficient enzyme. GSD I is a type of hepatic GSD caused by a deficiency in the enzyme glucose-6-phosphatase (G6Pase). G6Pase is responsible for the hydrolysis of glucose-6-phosphate (G6P) in the lumen of the endoplasmic reticulum and plays a central role in both gluconeogenesis and glycogenolysis. Without treatment, patients typically experience increased blood levels of lipids due to amplified triglyceride production, as well as increased lactic and uric acid levels. Additional characteristics of GSD I include short stature and muscle atrophy. What metabolic changes would you expect to find in patients with GSD 1?
-Increased lipogenesis -Decreased blood glucose levels -Decreased blood pH
Three most important aspects of glycogen breakdown?
-It involves cleavage of α-(1→6) glycosidic linkages. -It involves cleavage of α-(1→4) glycosidic linkages. -Glucagon has a limited effect on glycogenesis in skeletal muscle
The inflammasome can activate apoptotic pathways, and cleaves pro-interleukin-1β. Active interleukin-1β (IL-1β) is secreted from the cell and functions as an inflammatory cytokine. Biochemical analysis is still being performed on IL-1β to determine if this protein undergoes any additional post-translational modification; there is some evidence that it may be phosphorylated. Secreted IL-1β increases the expression of adhesion factors on endothelial cells, allowing white blood cells to move into potentially infected tissues. IL-1β also induces fever by initiating signal transduction in the hypothalamus. How is the activity of IL-1beta regulated?
-It is synthesized as a zymogen -pro-IL-1β is produced, and then cleaved and activated by the inflammasome. The initial inactive form of a protein is also known as a zymogen
An individual has obtained a level of moral reasoning wherein she feels as though it is of the utmost importance to uphold the laws and rules of her society, and she would under no circumstances break the law. According to Lawrence Kohlberg, what has this individual achieved?
-Level 2: conventional level of moral reasoning -Stage 4: authority and social-order maintaining orientation -the second level of moral reasoning involves comparing one's actions to society's views and expectations. Someone at this level accepts the conventional definitions of "right" and "wrong". The person described in the question stem does demonstrate a conventional acceptance of right and wrong by upholding the rules and laws of her society. -Kohlberg's fourth stage of moral reasoning is defined by a person's strict upholding of law, rules, and conventions in society, which describes what the individual in the question stem is doing
What describes a potential method of how G6PDH deficiency causes red blood cell lysis and anemia?
-NADP+ and glutathione can no longer be reduced, allowing the buildup of free radicals in the RBCs. -The passage explains that G6PDH deficiency leads to decreased production of NADPH and reduced glutathione. Reduced glutathione is required to remove free radicals and oxidative agents from causing cell damage and lysis. Decreased levels will lead to destruction of RBCs and hemolytic anemia
Three biggest reasons that phage therapy would be a more effective treatment option than antibiotics?
-Osteomyelitis, a bone infection where circulation at the infection site is poor -Chronic urinary tract infection caused by biofilm, a complex mixture of microbes that resist the effects of antibiotics -Pneumonia caused by penicillin- resistant Streptococcus Pneumoniae
Pyruvate dehydrogenase (PDC) kinase, when activated, decreases the activity of the PDC. A small-molecule inhibitor, AZD7545, targets pyruvate dehydrogenase kinase. What best describes the result of administration of AZD7545?
-PDC dephosphorylation and depletion of pyruvate -This is a 2x2 question where answering one of the two components of an answer choice will eliminate two possibilities. PDC kinase phosphorylates PDC and decreases its activity. An inhibitor of PDC kinase will decrease the quantity of phosphorylated PDC in the cell and enhance PDC activity. The PDC normally converts pyruvate into acetyl-CoA, releasing CO2 and generating NADH in the process. With increased PDC activity, pyruvate concentrations in the cell will mostly likely decrease, not increase
Multiple sclerosis (MS) is an autoimmune disease that results in demyelination of central nervous system axons. What could change as a result of this condition?
-Perception of sensory stimuli -Temporal summation in a postsynaptic neuron -Demyelination of an axon can result in slowed or lost conduction of action potentials, which could affect all types of stimuli perceived by the nervous system -Specifically, this affects the timing of neurotransmitter release by the neuron, which then changes the frequency of EPSPs or IPSPs in the postsynaptic cell -Action potentials are "all-or-none" phenomena, and their magnitude does not change
What is phage therapy and what viral agent would be the best use fro it?
-Phage therapy is the use of bacteriophage to treat bacterial infections. As described in the passage, the theory is that the virus will attack the disease-causing bacteria and not the human host. -The T4 bacteriophage is commonly used in research and uses E. coli as its host, thus T4-like coliphages could be a potential viral agent for phage therapy
The phosphoanhydride bond of ATP has a bond dissociation energy that is...
-Positive, and the breaking of this bond will require energy. -Bond dissociation energies are always given as positive values and are effectively defined as the potential energy of the separate atoms minus the potential energy of the bonded atoms. -Bonded atoms are always at a lower energy state compared to separate atoms, which are defined as 0 energy. Therefore, bond energy is equal to 0 - (a negative quantity), which yields a positive quantity
A biochemist attempts to cleave a short peptide of known sequence into two fragments using proteinase K (a proteolytic enzyme). However when running the cleavage product on a gel, only a single peptide with no change in molecular weight is observed. What is the most likely cause of this observation?
-Presence of multiple amino acids containing sulfur -Enzymatic proteolytic cleavage results in the hydrolysis of a peptide backbone at specific sites due to the stabilization of the transition state by the proteolytic enzyme -While this disrupts the primary structure of a protein, disulfide bonds can remain intact in oxidizing conditions and can result in the cleaved peptides remaining associated
Using Dalton's law, which of the following is the correct equation to determine the partial pressure of a component, Py, based on the concentration in parts per million, Cy?
-Py = (PtotalCy) / 106 -Dalton's law states that the sum of the partial pressures in a mixture of gases is equal to the total pressure of the mixture. Conversely, the partial pressure of a gas in a mixture is equal to the mole fraction of that gas multiplied by the total pressure of the gas, or Py = XyPtotal. Since Ptotal is in the numerator
Assuming the rate constants are the same for dissociation of all forms of oxyhemoglobin and that oxygen exerts the only order-determining effect, what could be an appropriate means of writing the rate law for formation of Hb(O2)2?
-Rate= Khb(O2)3 -Because rate laws are expressed with the appropriate rate constant followed by the reactants which exert an effect on the order of the reaction, the only acceptable answer is the rate law shown for dissociation of Hb(O2)3
What is a common technique used in cognitive behavioral therapy?
-Re-conditioning of mal-adaptive thought processes -One of the most common techniques used in cognitive behavioral therapy is reconditioning of maladaptive thought processes, which is generally achieved via the completion of homework assignments. -Common assignments involve negative-thought diaries, daily affirmations, and mood records, all of which require the client to focus on the precipitating events that cause maladaptive thoughts and to discover better ways to approach these situations
How does potassium work in myocytes?
-Repolarization in both the pacemaker cells and myocytes is due to the efflux of potassium -Repolarization results from efflux of potassium from the cells in both myocytes and pacemaker cells
Nocturnal enuresis and somnambulism are problems associated with which of the following stages of sleep?
-Stage 3 and 4 -Stages 3 and 4 of sleep are known as slow wave sleep. These are the deepest stages of sleep, but there is also moderate muscle tone present. The combination of being in a deep sleep and having the presence of muscle tone makes sleepwalking and bed-wetting more likely
If the n = 4 to n = 3 transition of an atom emits yellow light, which of the following transitions in this same atom could emit red light?
-The n = 5 to n = 4 transition -This question requires an understanding of the relative energies of visible light in the electromagnetic spectrum. Red light is lower frequency, longer wavelength, and lower energy than yellow light. Thus we are looking for a transition that will emit less energy than the n = 4 to n = 3 transition. Intuitively, n = 4 to n = 2 must release more energy than n = 4 to n = 3 It is necessary to recall that the gap between adjacent energy levels decreases with increasing distance from the nucleus. Thus the n = 5 to n = 4 is indeed a lower energy transition than the n = 4 to n = 3 transition.
A researcher studying the visual cortex attempts to record visually evoked responses from a single neuron but is not observing any change in the firing rate of action potentials when the stimulus is presented, regardless of how bright it is. What is the most likely reason for this observation?
-The orientation of the stimulus is not ideal -If the cell being recorded from responds to a light stimulus in one orientation, but not the other, this could explain the lack of a response
What is true regarding the hydroxyl (-OH) group bridging the two nickel centers in the active site of urease?
-The pKa of the bridging hydroxyl is lower than the pKa of methanol -The bridging hydroxyl group has three bonds, one to each Ni and one to the protic hydrogen. This means that the oxygen has a formal positive charge. This charge serves to polarize the O—H bond more than it is in a molecule like methanol, where there is no such formal charge, making the proton even more acidic. Likewise, the conjugate base of the bridging hydroxyl has no charge, and is therefore more stable than the conjugate base of methanol (methoxide). Since low pKa indicates strong acidity, the bridging hydroxyl will have a lower pKa than methanol.
What theory of personality most directly supports the notion that childhood experiences can determine whether an individual is likely to commit crime?
-The psychoanalytic perspective -According to the psychoanalytic perspective, childhood experiences shape who the individual becomes as an adult. -Abuse or neglect can lead to a damaged ego, which can result in the individual becoming more likely to commit crime
What is true regarding the function of the right and left ventricles?
-The right ventricle and left ventricle produce unequal systolic pressures, but have equal ejection fractions -The right ventricle only supplies the pulmonary circulation and would not require, nor have the ability, to produce the pressure needed to supply the systemic circulation, as the left ventricle does -Although the right and left ventricles produce unequal pressures, they do have the same stroke volume and therefore equal ejection fractions
Solomon Asch's famous study on conformity and Stanley Milgram's famous study on obedience both relied upon what?
-The use of confederates to adequately observe the subjects' behavior in relation to others. -Solomon's Asch's conformity experiments included one subject and several confederates who were posing as subjects; Stanley Milgram's obedience experiments included one subject who thought he or she had been randomly selected to be the "teacher"(who delivered shocks), and one confederate who the subject thought was another participant randomly selected to be the "learner" (who received the shocks). -Thus, both sets of experiments relied heavily on the use of confederates to fool subjects into believing they were interacting with other subjects in order to test their behavior in certain situations
The volume of a real gas under any set of conditions is smaller than the volume of an ideal gas under the same conditions. This is true because why?
-The volume of real gas particles is significant and reduces the free space in the vessel -The volume of a gas is defined as the free space within the vessel. Since ideal gas particles have insignificant volume, the free space is equal to the container volume. -The free space fro real gases is reduced by the volume of the real gas particles and therefore is always smaller than an ideal gas under the same conditions.
A scientist has a vial of cells that can be grown on plates in the lab. She does a transformation experiment on these cells and isolates the RNA a few days later. What is true about the cells under study?
-To extract the RNA, the researcher would have to break down the cell wall and the plasma membrane -Since the scientist did a transformation experiment, the cells under study must be prokaryotic (note that both prokaryotic and eukaryotic cells can be grown on plates in the lab, but the similar technique for eukaryotic cells is called transfection). -Prokaryotic cells have a plasma membrane and a cell wall, both of which must be degraded to extract the intracellular RNA.
alacyclovir (VACV) is a prodrug of acyclovir (ACV), both of which are commonly prescribed for herpes simplex virus (HSV) infections. As a metabolite of VACV, ACV acts by inhibiting HSV DNA polymerases. VACV is often utilized instead of ACV due to its ability to sustain higher levels of acyclovir in the serum even when ACV is dosed more frequently and in greater amounts. What is the most likely explanation for this finding?
-Valacyclovir more effectively weathers first-pass metabolism and thus larger amounts are readily available to be converted to acyclovir. -The stem indicates that valacyclovir is a prodrug of acyclovir and likely not active in its original form. -There is no indication from the data presented that valacyclovir is more quickly absorbed by the gastrointestinal tract. As shown in the figure, a much larger dose of ACV reaches a similar peak serum ACV concentration as a much smaller dose of valacyclovir, and at a similar rate; this suggests some inherent difference in how the drug and pro-drug are processed after absorption rather than a difference in the rate of absorption
M, a sixteen-year-old boy, has watched his friend successfully commit armed robberies. Which of the following best explains M's confidence that he can rob a convenience store himself?
-Vicarious learning -Bandura proposed multiple pathways to achieving self-efficacy, including vicarious learning. Vicarious learning is the observation of others succeeding at a task, which creates a sense of personal ability to succeed at similar challenges
What is always true regarding viral genomes?
-Viral genomes are made of either DNA or RNA, but never both
Light from visible lasers can heat tissue by what method?
-being absorbed by chromophores -absorption of photons by chromophores transforms their energy into heat and other forms. This is the mechanism of heating by light.
The body has many types of cells. Some cells never divide and are referred to as permanent cells. They remain in G0 and are regenerated from stem cells. Stable cells enter G1 from G0 phase only when stimulated to do so. Labile cells effectively constantly divide, having a short G1 phase and never entering into G0. What cells are matched with their correct division classification? The cells are red blood cell, hepatocyte (liver cells) and skin cell
-permanent= red blood cell; Neurons, red blood cells (RBCs), and skeletal and cardiac muscle cells are permanent cells and do not divide -Stable= hepatocyte (liver cell); Stable cells include hepatocytes (liver cells) and lymphocytes (T cells and B cells) -Labile= skin cell; Bone marrow, gut epithelium, skin, and hair follicles are all composed of labile cells. This is important to realize because these are the cells that are affected by chemotherapeutics, which try to target rapidly-dividing cancer cells. This is why the most common side effects of chemotherapy include hair loss, diarrhea and gastrointestinal upset, and bone marrow suppression
Two biggest aspects to in-group favoritism
-prejudice against an out-group -discrimination against an out-group
In a state of starvation, the body utilizes amino acids for gluconeogenesis and excretes the nitrogen byproduct, creating a negative nitrogen balance. Thus, the level of mRNA expression for CPSI and OTC during starvation is most likely to...
-remain about the same because increased enzymatic activity is achieved through reduced breakdown of the enzymes -Negative nitrogen balance from the catabolism of muscle and other protein-rich tissues implies that increased activity of CPSI and OTC is needed to avoid hyperammonemia. However, because amino acids are being diverted to gluconeogenesis during starvation, the more likely means for boosting enzymatic activity is inhibiting breakdown rather than increase transcription and translation
What forms when sphingomyelin is hydrolyzed with acid?
-sphingosine -choline -fatty acids
If Albert, who was primed to fear white rats when he was a child, gets a stuffed white rat at a fair but is excited, what does this connect to?
-the Schachter-Singer theory of emotion -The Schachter-Singer theory of emotion suggests that while several different emotions (such as anger, fear, or excitement) can all elicit the same physiological response (sweating, heart racing, etc.), the context of the situation determines how an individual will interpret the emotion. -In this example, Albert experienced a physiological response that he interpreted as excitement because of the context
What is the actor-observer bias?
-the actor/observer bias occurs when individuals attribute their own actions to situational causes, as opposed to dispositional factors. In this instance, the youth is blaming the situation (i.e.,someone else did something that caused him to act)
A parallel-plate capacitor (with a vacuum in between the plates) is connected to a battery. In Step 1, the distance between the plates is increased while the battery is still attached. In Step 2, the battery is disconnected and a dielectric is placed in between the plates. Which of the following is true about the change of potential energy in each of the steps?
-ΔPE1 < 0 and ΔPE2 < 0 -The equation for capacitance is C = κε0A / d, where κ is the dielectric constant (κ > 1), ε0 is a constant, A is the area of the plates and d is the separation between plates. In Step 1, d increases, therefore C decreases. In Step 2, κ increases, therefore C increases. The potential energy stored in a capacitor can be written as (1/2)CV2 or Q2 / 2C. In Step 1, the battery remains attached which means that V remains constant, so use the equation for PE with the V term. In that case, PE ∝ C, so decreasing C means the potential energy must therefore decrease. -In Step 2, the battery is disconnected, which means that Q remains constant, so use the equation for PE with the Q term. In that case, PE ∝ 1 / C, so increasing C means the potential energy must therefore decrease.
Based on the data depicted in Figure 2, the Km for uninhibited NAG activity is likely which of the following (in µM)?
0 < Km < 1
An ideal gas contained in a piston begins with pressure P0, volume V0, and temperature T0. It undergoes isothermal expansion to volume 2V0. It then undergoes isobaric compression back to volume V0. Finally, its pressure is increased by an isochoric process until it returns to its original state. Which of the following best approximates the work done by the gas on the environment during this sequence?
0 < W < P0V0 / 4 The work done during a thermodynamic process is the area enclosed by the set of process curves on the PV diagram. In this case, three vertex points are given or implied: (P0, V0), (P0 / 2, 2V0), and (P0 / 2, V0), where the value of the pressure after the isothermal (constant temperature) expansion is implied by the fact that PV is constant (Boyle's law): if volume doubles, pressure must halve. To estimate the area contained by the three curves, plot the three points on a PV graph and connect them to form a triangle. Note that this will overestimate the area, because the isotherm is a hyperbola, not a straight line (see the PV graph below). The formula for the area of a triangle is one half base times height, yielding 1/2 × P0 / 2 × V0 = P0V0 / 4 (which, again, is an overestimation).
A car drives to a location with an average speed of 30 m/s and makes the return trip with an average speed of 40 m/s. What is the magnitude of the car's average velocity for the entire trip?
0 m/s Average velocity is defined as total displacement over time. Since displacement is a vector that points from the beginning point to the end point, its magnitude is zero (since the beginning and end points are the same). Therefore the magnitude of the average velocity is zero.
Equation to find the kinetic energy of a charged ball
1/2MV^2= qEd q is the charge in C and E is the electric field strength in N/C
humanistic psychology
A clinical viewpoint emphasizing human ability, growth, potential, and free will. It is also known as person-centered therapy and was developed by Carl Rogers
Fat soluble vitamins
A, D, E, K
Fingolimod, an immunosuppressive drug, acts as an S1PR agonist, which subsequently inhibits egress of T lymphocytes by triggering internalization and destruction of S1PR. In MS patients, fingolimod is shown to affect CD4+ cells more than CD8+ cells. Based on information in the passage, which of the following is most likely the main therapeutic benefit of a medication like fingolimod in patients diagnosed with MS?
Fingolimod decreases the amount of T lymphocytes released from the lymph node, thus reducing the likelihood that autoreactive lymphocytes will reach the CNS. The passage focuses on fingolimod's inhibition of the egress of lymphocytes from the lymph node. This would reduce the overall number of lymphocytes in circulation and, most importantly, reduce the number of autoreactive lymphocytes that may recirculate without inhibition
When is fractional distillation used?
Fractional distillation is most often used to separate a mixture of liquids with boiling points differing by less than 25°C
Why won't a compound form a cyclic structure?
If it has a phosphate group, than it cannot form a cyclic structure
Which theory of emotion postulates that emotion stems from a physiological response to a stimulus?
James Lange Theory
Who invented psychoanalysis?
Sigmund Freud
A standard galvanic cell is constructed using Cr and Pt electrodes and 500 mL of the metal ion solutions in each half-cell. When a total of 6.0 g of metal is deposited at the cathode, what is the new associated concentration of the metal ion in the oxidation half-cell? Cr + 3e -> Cr(s) -0.74V Pt + 2e -> Pt (s) 1.19V
The spontaneous reaction between Cr and Pt and their respective ions based on standard reduction potentials given in Table 1 is 2 Cr + 3 Pt2+ → 2 Cr3+ + 3 Pt, with an E°cell = 1.93 V. This indicates that Pt2+ is reduced at the cathode to deposit 6 g of Pt, and the Cr electrode is being oxidized to Cr3+ in the oxidation half-cell. This will increase [Cr3+] in the solution from 1 M, which is the concentration required for a standard cell To determine the new concentration, convert the mass of Pt into moles of Cr3+: (6 g Pt) x (1 mol Pt/200 g Pt) x (2 mol Cr3+/ 3 mol Pt) = 0.02 mol Cr3+ Five hundred milliliters of a 1 M solution will contain 0.5 mol Cr3+ to begin, so it will contain 0.52 mol in 0.5 L after the reaction indicated The new concentration will be 1.04M
First order reaction
a reaction in which the reaction rate is proportional to the concentration of only one reactant
function of somatosensory cortex
receives all sensory input from the body and interprets it
What is cultural relativism?
recognizing differences across cultures without judging those differences as positive or negative
Electron capture
the process in which an inner orbital electron is captured by the nucleus of the atom that contains the electron
What is the self-serving bias?
the tendency to blame others for one's own actions and not take responsibility for failures is known as the self-serving bias. In this instance, the youth is not taking responsibility for his actions and is blaming someone else
