MCAT-PREP GS-Free (New) - Questions I missed/to review
If k = 40 000 N/m, then how much energy does it take to compress Substance Q42 from its relaxed length (10 cm) to a length of 9 cm? (A) 2 J (B) 20 J (C) 40 J (D) 100 J
The energy it takes to compress the spring will be the same as the potential energy now stored in the spring as a result of it being compressed. The potential energy in a spring is given by W = 1/2 k x^2. where k is the spring constant and x is the distance of compression. The last sentence in the passage says the spring is 10 cm long in its relaxed state. Therefore, when compressed to a length of 9 cm, the distance of compression is 1 cm (x = 1 cm = 0.01 m).
How does the total resistance change with longitudinal distance along the axon (as longitudinal distance increases, more RC (resistor/capacitor) circuits are added in parallel)? (A) Resistance is independent of distance (B) Resistance increases (C) Resistance decreases (D) Resistance increases exponentially
The length of the axon can be represented as a simple RC circuit, with resistors that are in parallel along the longitudinal axis. With this circuit model representation, the total resistance formula can be used to deduce the correct answer: 1/R(tot) = 1/R1 + 1/R2 + 1/R3 + ... As more resistors are added to the parallel circuit, total resistance decreases. Therefore, answer choice C is correct. Answer choice A is incorrect because it contradicts the information in paragraph 1 regarding the resistors in parallel. Answer choice B is incorrect because it suggests that the total resistance consisted of resistors connected in series: Rtotal = R1 + R2 + R3 + ... Answer choice D is incorrect because the exponential increase in resistance is not supported by the information in the passage.
Which of the following statements about the mechanism of allosteric control of enzyme activity is correct? (A) Allosteric enzymes show greater sensitivity to changes in substrate concentration compared to classical type enzymes with hyperbolic kinetics. (B) Allosteric enzymes show Michaelis-Menten kinetics. (C) Allosteric enzymes show reduced sensitivity to changes in substrate concentration compared to classical type enzymes with hyperbolic kinetics. (D) Allosteric enzymes are typically single-subunit enzymes.
(A) Allosteric enzymes are multi-subunit proteins which have allosteric sites ('allo' means other) separate from the active site to which bind allosteric modifiers (activators or inhibitors). These cause conformational changes in the enzyme, giving sigmoidal kinetics rather than the hyperbolic kinetics of classical enzymes. This affects the affinity of the enzyme for its substrate and hence the activity of the enzyme. An allosteric activator increases the affinity whereas an inhibitor decreases it. The sigmoid kinetics means that over a critical range, the enzyme is more sensitive to changes in substrate concentration than is the case for those with hyperbolic kinetics.
A mixture of dipeptides was being evaluated by researchers. At pH 7.4, which of the following dipeptides in the mixture would most likely bind to a cation exchange column? (A) Val-Lys (B) Tyr-Glu (C) His-Asp (D) Leu-Cys
(A) Cation exchange columns bind positive charged species and will thus bind dipeptides with a net positive charge. At near neutral pH, only the Val-Lys dipeptide has a net positive charge.
An imine is broken down into an amine and a carbonyl group. The reaction likely involves: A. hydrolysis. B. oxidation. C. decarboxylation. D. hydration.
(A) Notice that the C-N bond is broken, so there is lysis. Also, the elements of water are incorporated into the products: O in the alpha keto acid and 2 H's in the amine. The process is thus hydrolysis (and answer choice A is correct) . Note that this reaction is simply the reverse of imine formation.
Both maltose and cellobiose share certain features in common. Which of the following is NOT consistent with both molecules? (A) They have beta-linkages. (B) They are carbohydrates. (C) They have the same molecular formula. (D) They are dimers.
(A) On the surface: Cellobiose consists of two glucose molecules (= disaccharide) linked by a β(1→4) bond. Maltose (= malt sugar) is a disaccharide joined with an α(1→4)bond. It is due to the difference in bonding that humans can digest maltose but not cellobiose. Since they are both glucose dimers, they share the same molecular formula. Going Deeper: We can use process of elimination to deduce the correct answer. Answer choice B is an incorrect choice, because both cellobiose and maltose are carbohydrates. This is a correct statement. Answer choice C is an incorrect choice, because both cellobiose and maltose do indeed share the same molecular formula, C12H22O11. This is a correct statement. Answer choice D is an incorrect choice, because both cellobiose and maltose consist of glucose dimers. This is a correct statement. Answer choice A is the correct choice because it contains an incorrect statement. Only cellobiose consists of beta-glycosidic bond.
A spherical air bubble is rising in a test tube which is illuminated from one side by a flashlight. Consider points A and B on the surface of the bubble, which are on opposite sides of the bubble. What happens to a ray of light incident on the air bubble at A? (A) Reflection at both surfaces (B) Reflection at A; no reflection at B (C) Reflection at B; no reflection at A (D) no reflection at either surface
(A) Reflection is the process by which light rays bounce back into a medium from a surface with another medium. Note that there are 2 surfaces, both A and B, which meet the criterion for reflection. Remember: just because some light reflects, does not mean that all of the light reflects. Specifically, some of the light will transmit completely through the bubble while some would have been reflected at A and some at B.
Which of the following types of radiation has a longer wavelength than infrared radiation? (A) Radio waves (B) Visible light (C) Ultraviolet radiation (D) Gamma rays
(A) The electromagnetic spectrum from longer to shorter wavelength goes as follows: radiowaves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays. Side Note: Long wavelengths = low frequency, and low frequency = low energy. Radio waves are low energy waves. The velocity v = (frequency)(wavelength) so when the medium/environment is the same (constant velocity) then longer wavelengths have lower frequencies. The energy of a wave = (Planck's constant)(frequency) so low frequency = low energy.
An imine formation reaction can be most closely described as which of the following? (A) Condensation (B) Decarboxylation (C) Nucleophilic substitution, first order (D) An aldol reaction combined with hydrolysis
(A) The lone pair of electrons from the amino group of the amino acid attacks the carbon of the carbonyl group on the pyridoxal phosphate effecting a nucleophilic addition (2nd order). Subsequently, water is eliminated creating a C=N bond (= an imine). The reaction can be characterized as either condensation or dehydration (note: the opposite would be the adding of water to break a single organic molecule into 2 separate molecules = hydrolysis).
In the passage it is claimed that "people who score higher on these tests are not necessarily more intelligent" and that any conclusion that they are may lack validity. To which type of validity is the author LEAST likely referring? (A) Internal validity (B) External validity (C) Content validity (D) Construct validity
(A) This is a psychology question that requires knowledge about the category "making sense of the environment," more specifically about intellectual functioning and methods of studying it. The correct answer is A. Questions of validity are often brought up when discussing intelligence measures. Internal validity refers to whether the inferences or conclusions drawn can be linked back to the independent variable(s). In the example provided in the passage, no independent measures were mentioned. That is, internal validity concerns the design of the experiment. It is often contrasted with external validity, which is concerned with the way findings obtained in a specific study can be generalized to other situations and people. The passage questions precisely whether the attribute of intelligence can be generalized, which makes it more likely that the claim in the passage is referring to external, not internal, validity. Content validity refers to the extent to which all facets of a given construct are reflected in the adopted measure. As the passage mentions, each one of the tests assesses different aspects of intelligence. In particular, g-factor tests such as Raven's Progressive Matrices exclusively aim at assessing fluid intelligence and not crystallized intelligence. They do not reflect every facet of what has been associated with the construct of intelligence. Construct validity refers to the extent to which the instrument or psychological assessment tool is measuring what it is supposed to be measuring. Given that different aspects of intelligence are measured via the two tests, and in particular Wechsler tests, which include a wide range of subscales that assess different skills, it is possible that the tests are not exclusively assessing "intelligence" but some related or additional aspect, such as declarative memory.
According to Robert Sternberg's approach, intelligence can be described as: (A) analytical intelligence, creative intelligence, and practical intelligence. (B) the g-factor. (C) visual-spatial intelligence, verbal-linguistic intelligence, bodily-kinesthetic intelligence, naturalistic intelligence, logical-mathematical intelligence, musical intelligence, interpersonal intelligence, intrapersonal intelligence. (D) verbal comprehension, perceptual speed, numerical ability, reasoning, word fluency, associative memory, spatial visualization.
(A) This is a psychology question that requires knowledge from the category "making sense of the environment," more specifically knowledge about theories of intelligence. The correct answer is A. Robert Sternberg drew on the idea that intelligence is more than one single ability. He saw three different factors as defining intelligence: analytic intelligence (i.e., problem solving), creative intelligence (i.e., capacity to deal with new situations), and practical intelligence (i.e., ability to adapt to a changing environment). His notion of intelligence is based on Howard Gardner's idea that intelligence cannot be limited to a test score but is a culturally varied expression of different dimensions. While Gardner based his dimensions on more academic categories (visual-spatial intelligence, verbal-linguistic intelligence, bodily-kinesthetic intelligence, naturalistic intelligence, logical-mathematical intelligence, musical intelligence, interpersonal intelligence, intrapersonal intelligence), Sternberg's approach focused on more general dimensions. In opposition to those theories about intelligence are approaches that base intelligence on a numerical score. These would include Louis Thurstone's theory of primary mental abilities. He saw intelligence as consisting of verbal comprehension, perceptual speed, numerical ability, reasoning, word fluency, associative memory, and spatial visualization. Others perceive intelligence as general cognitive ability expressed across different categories. Charles Spearman analyzed different mental aptitude test results and saw a pattern emerging. People who scored high on one test would usually score high on all of them, and people who performed badly in one category performed badly overall. He concluded that intelligence must be a general cognitive ability, the g-factor.
The passage mentions demographic trends. Which of these is NOT a genuine demographic trend in the United States? (A) A lower dependency ratio (B) An aging population (C) A bigger foreign-born population (D) A lower birthrate
(A) This is a sociology question covered by the category "demographic characteristics and processes," which includes having and developing an understanding of theories of demographic change. The correct answer is A. The dependency ratio refers to the relationship between the working and the dependent population. Due to the aging population and the falling mortality rate in the U.S., there is a rising dependency ratio, with more dependent people compared with a smaller working-age population.
50 grams of glucose (C6H12O6) and 50 grams of sucrose (C12H22O11) were each added to beakers of water (beaker 1 and beaker 2, respectively). Which of the following would be true? (A) Boiling point elevation for beaker 1 would be greater than the boiling point elevation for beaker 2. (B) Boiling point elevation for beaker 1 would be less than the boiling point elevation for beaker 2. (C) The same degree of boiling elevation will occur in both beakers. (D) No boiling point elevation would be observed in either of the beakers.
(A) This question tests your understanding of colligative properties. From the equation Tb = Kbm, where Kb is constant, "m" or the molality is the factor to be considered. Recall that m = (Number of moles solute)/(1000 g solvent) and number of moles = (Mass of substance present)/(Relative molecular mass). Since glucose has a smaller relative molecular mass than sucrose, there will be a greater number of moles of glucose present when equal masses of the two substances are used. Therefore, the molality of glucose is greater and hence the boiling point elevation is greater and Answer choice A is correct. "The oxygens do not always translate to more hydrogen bonding - this would depend on what other atoms are connected to oxygen and electronegativity. This question is not focusing on boiling point, but rather, the degree of boiling point elevation. For this question, you will need to use the boiling point elevation formula as stated in the explanation section. Glucose has a higher molality as compared to sucrose of the same mass of 50g, therefore, it increases the boiling point more than sucrose."
If the goal of the health communication is to influence individuals, families, neighborhoods, medical and social service organizations, and ultimately public health policy, health promoters are adhering to: (A) Urie Bronfenbrenner's ecological systems theory. (B) Murray Bowen's family systems theory. (C) John Bowlby's attachment theory. (D) Milton Gordon's assimilation theory.
(A) is correct. Ecological systems theory was first applied to understand child development and their socialization. It maintains that human behavior (in this case, health behavior) is influenced by multiple levels or spheres of influence of different orders, including the microsystem, which is related to the individual (e.g., the patient's beliefs, personality, past experiences, etc.); the mesosystem, which is related to those with whom the person relates to directly (e.g., the family, community, neighborhood, workplace, school, friends, etc.); the exosystem, which relates to institutions and organizations which regulate that person's community and with which the person does not often interact directly (e.g., health services, social services, legal institutions, industry, mass media, etc.); the macrosystem, which relates to that person's cultural milieu (e.g., culture, traditions, laws, etc.); and the chronosystem, which relates to the dimension of time (e.g., when the person was born, when they lost their parents, etc.). The latter system was introduced a later stage of his career.
Which one of the following chemicals would UNLIKELY be involved in the onset of a panic attack? (A) Melatonin (B) Epinephrine (C) Norepinephrine (D) Serotonin
(A) is correct. Melatonin helps to sustain people's circadian rhythms. It is mainly involved in the sleep-wake cycle regulation. It is secreted into the bloodstream at night, inducing drowsiness and making the person feel sleepy. It has been found to be effective in the treatment of anxiety due to its calming effects. These effects suggest that melatonin is not involved in the outset of acute anxiety episodes. Moreover, no findings have yet associated low or high levels of melatonin with anxiety disorders.
If researchers from the Asian grocery store program offered a $5 coupon for groceries to women if they stopped by the exhibit booth, which persuasion strategy is being utilized? (A) Social exchange technique (B) Physical attractiveness then manipulation technique (C) Fear then relief technique (D) Lowball technique
(A) is correct. The concept of social exchanges as a persuasion tactic assumes that if a person is given a physical or psychological reward, then they will be more likely agree to the request in the future. B. This is incorrect. Physical attractiveness is a factor that promotes compliance. However, a $5 coupon is given to participants, and thus is unrelated to physical attractiveness. C. This is incorrect. The fear-then-relief strategy is a method where feelings of anxiety or apprehension are aroused and then the threat is quickly eliminated by replacing it with a small request. An offer of a $5 coupon is very unlikely to raise anxiety. D. This is incorrect. Lowball is a persuasion technique where the individual is offered an item at an attractively low price, and once the person has agreed, the price is increased. This was not what happened.
How is the basic reproduction number related to β and γ? (A) R = βγ (B) R = β/γ (C) R = β^2γ (D) R = β/γ^2
(B) According to the passage, β is the contact rate and γ is the recovery rate. This problem can be solved by analyzing the units of β, γ and R. The parameter β has the units of cases/time, γ has the units of 1/time, and R has the units of cases. So, to match the units, R = β/γ since Unit[R] = Unit[β]*Unit[γ] = (cases/time)*(1/time) = cases*(time/time) = cases Going deeper: Since γ is the recovery rate then 1/γ is the time till recovery. As β is the contact rate, then 1/β is the time between contacts. Therefore, R, which is the number of new infected cases generated before the infected individual has recovered, must be (1/γ)/(1/β) = β/γ.
Typical classification of inversions is determined by the location of the region that links sister chromatids, the centromere. If the centromere lies outside of the inversion, the inversion is called paracentric (see Figure 2a). If the centromere lies within the inversion, the inversion is called pericentric. A particular chromosome in the hamster has the sequence ABC*DEFGHI with * denoting the centromere. If an inversion loop contains the rearrangement, ABC*DHGFEI, the original inversion could be described as? (A) Crossed over (B) Paracentric (C) Pericentric (D) Double inversion
(B) Recall that an inversion involves a segment of the chromosome breaking off, rotating, and reinserting itself. Thus, you can visualize that the gene segment, EFGH, has flipped. And since the inversion did not include the centromere, that is the centromere was located outside of the inversion, it is paracentric.
TABLE 2 [KCl] (mM) || RibH--> RibH2 0 || 12.1±1.6 25 || 15.0±3.2 50 || 17.0±0.6 200 || 21.5±4.6 300 || 23.0±8.2 400 || 23.7±5.3 Given the data in Table 2, what is the likely approximate Km value for riboflavin (RibH) reduction? (A) 25 mM (B) 50 mM (C) 150 mM (D) 300 mM
(B) The passage suggests that the reactions measured within the pump obey Michaelis-Menten kinetics. In such reactions, Km is the substrate concentration at which the reaction proceeds at half of its maximum rate. The maximum rate can be determined by comparing reaction rates at different substrate concentrations, which can be obtained in Table 2. KCl serves as a substrate in this reaction and the maximum measured speed for riboflavin reduction is 23.7 s^-1. However, at 0 mM of KCl the reaction has an initial rate of 12 s^-1, which should be subtracted as a baseline reference. The corrected maximum velocity is therefore: 23.7 - 12 = 11.7 s^-1. Half of the corrected maximum velocity is 5.85 s^-1, which would be equivalent to 17.85 s^-1 when we add the baseline reference of 12 s^-1. The reaction rate measured at 50 mM of KCl is 17 s^-1, suggesting that the Km for this reaction is about 50 mM.
Which of the following statements about the oxidative phase of the pentose phosphate pathway (PPP) is correct? (A) The rate-limiting reaction of the PPP is catalyzed by glucose-6-phosphatase. (B) The PPP supplies ribose-5-phosphate and NADPH in the quantities the cells require. (C) The PPP oxidizes NADPH to NADP+. (D) The PPP generates NADH.
(B) The pentose phosphate pathway (PPP) supplies ribose-5-phosphate for nucleotide and nucleic acid synthesis, and for synthesis of coenzymes such as NAD+, FAD and CoA. The PPP also supplies NADPH for reductive biosyntheses. It is a route for excess pentose sugars to be brought into the mainstream of glucose metabolism. The PPP has two main parts. One part is the irreversible oxidation of glucose-6-phosphate to ribose-5-phosphate while NADP+ is reduced to NADPH (therefore, answer choice C and D are both incorrect). The rate-limiting reaction here is catalyzed by glucose-6-phosphate dehydrogenase (therefore, answer choice A is incorrect). This section of the pathway is controlled by the availability of NADP+. The second part of the pentose phosphate pathway is made up of nonoxidative reaction sequences that interconvert sugars according to the cell's needs. Excess ribose-5-phosphate is converted to glycolytic intermediates by a sequence of reversible reactions. Therefore, answer choice B is the correct answer.
Psychologists of the behaviorist school use the concepts of neutral, conditioned and unconditioned stimuli, and conditioned and unconditioned response. In Ivan Pavlov's research, which of the below options is true? (A) The bell was an unconditioned stimulus, the food was a conditioned stimulus, and salivation was the conditioned response. (B) The bell was a neutral stimulus developed into a conditioned stimulus, the food was an unconditioned stimulus, and the salivation was an unconditioned response. (C) The bell was an unconditioned stimulus developed into a conditioned stimulus, the food was a conditioned stimulus, and the salivation was an unconditioned response. (D) The bell was a conditioned stimulus, the food was an unconditioned stimulus, and the salivation was a conditioned response.
(B) This is a psychology question covered by the category "attitude and behavior change," which includes having and developing an understanding of concepts related to stimulus and response. The correct answer is B. In Pavlov's research, which involved studying classical conditioning in dogs, the ringing of a bell was paired with the stimulus of food, eliciting a response of salivation at the time of the bell ringing that was formerly only forthcoming as a response to the stimulus of food. The dogs then associated the ringing of the bell with food, and thus salivated as a result of the ringing of a bell. In Pavlov's research the bell was a neutral stimulus that, through pairing with an unconditioned stimulus, was developed into a conditioned stimulus. The food was an unconditioned stimulus, and the salivation was an unconditioned response.
Imagine that the attention of the person surfing the Internet was temporarily distracted by the described environmental stimuli. Which of the following constructs drawn from existing attention cognitive models would be the LEAST relevant for the description of what this person was experiencing? (A) Focused attention (B) Attention deficit (C) Divided attention (D) Selective attention
(B) This is a psychology question covered by the category "making sense of the environment," which specifies that knowledge about cognitive attention models and constructs such as divided attention is required. The correct answer is B. Attention deficit is a term sometimes used to refer to the attention deficit and hyperactivity disorder psychiatric diagnosis, and principally when addressing attention-related symptoms. Thus this term is often used to refer to dispositional traits, such as being unable to follow through a task for a relatively long period of time regardless of the particular situation. It does usually not refer to situational aspects, such as a temporary lack of attention. Moreover, unlike the other constructs, the term is not used in cognitive attention models. Focused attention refers to a person's concentration on one source of informational input, sensory stimulus, or activity to the exclusion of any other. This was precisely what the person in the scenario was unable to do—to focus on the Internet activity to the exclusion of anything else (e.g., listening to the dogs barking). Divided attention is often contrasted with focused attention. It refers to how people divide their attentional resources across several simultaneous tasks. Yet attending to environmental stimuli can be considered a task. For example, if the person in the scenario managed to pay attention to the dogs while surfing the Internet, then he would have succeeded at dividing his attention. Selective attention refers to people's ability to filter out relevant information from a background of multiple, divergent, and competing information. The person in the scenario was distracted by irrelevant stimuli, and hence his selective attention was inefficient.
What technique was being used by researchers from the Asian grocery store program if they tried to recruit more participants by asking for referrals to those who had previously agreed? (A) Random digit dialing (B) Snowball sampling (C) Purposive sampling (D) Simple random sampling
(B) is correct. Snowball sampling is a non-probabilistic sampling technique that involves asking research subjects to refer or recommend people from their social network who might be interested in participating. The idea is that over time, the "snowball" gets larger. A major limitation of this type of sampling strategy is the amount of sampling bias introduced into the study. Specifically, study participants may lack diversity. A. This is incorrect. Random digit dialing is a probabilistic sampling strategy that randomly selects phone numbers within area codes to recruit participants. C. This is incorrect. Purposive sampling is a non-probabilistic sampling strategy that looks for certain characteristics and only selects those who fulfil selection criteria. D. This is incorrect. Simple random sampling is a probabilistic sampling technique that will typically use a number generator to select subjects for a study.
How would a scholar utilizing social control theory explain domestic violence? (A) Domestic violence is modeled and learned. (B) Domestic violence is triggered by the lack of regulations and cohesive networks in society. (C) Labelling as deviant the reactions of both the perpetuator and the victim of violence reinforces such behaviors. (D) Domestic violence is caused by an interaction of factors from the micro, meso, and macro-levels causing a feedback loop that then results in a loss of systems control.
(B) is correct. Social control theory maintains that social networks and social control mechanisms must be in place in society to regulate its members. These connections and their control mechanisms promote pro-social behaviors and reduce anti-social behaviors. Someone adopting this perspective would claim that lack cohesive social bonds and associated social control mechanisms would be responsive for violence. Thus, an intensification of social bonds and associated control mechanisms would diminish aspects such as domestic violence. D. This is incorrect. Systems theory examines a problem like violence as a social interaction stemming from the micro-level (i.e., individual level), the meso-level (e.g., family, neighborhoods, schools, etc.) and macro-level (e.g., government, culture, institutions, etc.). This is unrelated to social control theory.
Substance Q42 is fully expanded and then contracts in response to a 5.0 amp current. Which of the following best represents the conversion of energies in the process described? (A) Potential --> kinetic --> mechanical (B) Potential --> mechanical --> kinetic (C) Electrical --> mechanical --> potential (D) Potential --> mechanical --> electrical
(C) According to the question and the passage, current is applied (Electrical Energy) to Substance Q42 causing it to contract (Mechanical Energy); and finally, in the contracted state, using the spring analogy, Substance Q42 has potential energy. Going Deeper: if you chose an answer beginning with "Potential" energy then we should examine this closer. Certainly, if Q42 was a spring and it was "fully expanded" then it would have significant stored (potential) energy that would try to return the spring to its native state. This problem is different because the fully expanded state of Q42 is indeed the native state. The passage suggests that if you had Q42 fully expanded, it would do nothing unless a current is applied. In other words, expanding Q42 did not store energy in the sense of a spring. On the other hand, once contracted after the application of current, Q42 would expand spontaneously due to its stored potential energy.
Which of the following would be the strongest oxidizing agent? (A) Fe (B) Fe^2+ (C) Fe^3+ (D) HFeO2-
(C) On the surface:Oxidizing agent is the ion that receives electrons and undergoes a reduction. Here we can see that Fe3+ have the highest oxidation number, and can receive 3 electrons to be reduced to Fe. Therefore, this makes Fe3+ the strongest oxidizing agent, and answer choice C as the correct answer. Answer choice C contains the most oxidized form of Fe that can receive the most electrons and become reduced. This makes this answer choice the strongest oxidizing agent and is the correct choice.
Using ultrasound waves targeted at the brain, a team of researchers restored memory to mice with symptoms of Alzheimer's disease. The ultrasound technique removed amyloid beta plaques from the brains of the mice. Which of the following is the most likely explanation for why ultrasonic waves break apart plaque formations? (A) Mica bonds in plaque formations absorb heat generated by the ultrasonic waves. (B) The plaque formations are moved in the direction in which the ultrasonic waves travel. (C) The plaque formations vibrate at a resonant frequency equal to the frequency of the ultrasonic waves. (D) The medium in which the ultrasonic waves travel forces the plaque formations to break apart.
(C) The frequency of the ultrasonic waves must be equal to or is an integral multiple of the natural frequency of the plaque formations. As a result the plaque formations resonate when forced to vibrate by the ultrasonic waves; the amplitude of vibrations of the plaques are such that they break apart/shatter like a wine glass does in response to a resonant frequency.
Which statement is LEAST supported by the model? (A) Once enough people have recovered, susceptible individuals are less likely to contract the virus. (B) The disease does not always die out. (C) Everyone will get the disease. (D) Recovered people cannot be reinfected.
(C) The model does not state that everyone will be infected. If everyone around an infected individual has already contracted the disease and recovered, the infected individual cannot continue to transmit the disease, thus potentially sparing some susceptibles. Going deeper: When enough people have recovered, infected individuals are less likely to come into contact with a susceptible individual. So the susceptibles are less likely to become infected. This phenomenon is called herd immunity. Once a threshold has been reached in the number of people recovered, they become a barrier to further spreading of the disease, and eventually the disease becomes eliminated. Smallpox was eradicated due to worldwide herd immunity, but not every disease can be eradicated this way.
Which concept best describes how the symptoms of organic and psychological disorders, such as hallucinations, sometimes resemble each other? (A) Biological fallacy (B) Associationism (C) Psychological masquerade (D) Reflected appraisal
(C) This is a psychology question covered by the category "individual influences on behavior," which includes having an understanding of psychological disorders. The correct answer is C. Whenever a medical condition matches the presentation of a psychological disorder, clinicians may develop the erroneous conviction that they are facing a purely psychological disorder with a purely psychological cause, when actually psychological symptomatology is being caused by a medical, organic cause. When this happens, clinicians are faced with a "psychological masquerade". There are a variety of medical conditions that can cause mental health symptoms and provoke a psychological masquerade, such as the case of tumor-caused hallucinations described in the passage. Understanding whether psychological symptoms are masking medical problems is critical.
If a study aims at being universally applied, adopts a Likert-type scale and includes the items "I want to display self-control about food" and "I am terrified of being overweight," what is it most probably trying to measure? (A) Social etiquette (B) Anorexia nervosa (C) Eating attitudes (D) Bulimia nervosa
(C) This is a psychology question covered by the category "individual influences on behavior," which involves knowing about attitudes and how to assess them. The correct answer is C. Attitudes are one of social psychology's areas of interest. According to Icek Ajzen, a well-known researcher in this area, attitudes are relatively enduring dispositions that influence behavior in regard to a particular aspect. Harris Trandis identifies three attitude components: affective, behavioral (or conative), and cognitive. The examples of survey items provided in the question assess affective ("terrified") and conative ("I want to display self-control") aspects of respondents' attitudes toward eating. Although eating-related attitudes are used to diagnose anorexia and bulimia nervosa, two psychological disorders that involve abnormal eating behavior, what the survey assesses is attitudes—not the existence of a psychological disorder. For example, not everyone who wants to display self-control around food and eats slower than others would be diagnosed as having anorexia or bulimia by a psychiatrist. That is, people's eating attitudes, as detected via the survey, can be interpreted and related to the diagnostic criteria employed to diagnose these disorders, but they do not directly assess the existence of these disorders. Social norms are sets of rules that are shared by a group of people and that regulate their behavior. Social etiquette amounts to a set of social norms that regulates polite behavior in particular. Although eating behavior is often subject to social etiquette, it varies from culture to culture and even from family to family. Therefore it is unlikely that a survey with universal intents is measuring social etiquette.
Table 1 associates declarative memory with the hippocampus and the medial temporal lobe. Which of the following tasks could be used in a neuropsychological study concerned with this type of memory? (A) Test subjects would be trained for a week in a motor task, namely working on a choreographed dance until they had memorized every aspect of it. After two weeks they would be asked to perform the choreography. (B) Test subjects would be presented with a list of words. Immediately afterward, they would be asked to repeat from memory every word listed. (C) Test subjects would answer a set of general common knowledge questions, such as naming the planets of the solar system and the number of sides in several geometric figures. (D) Test subjects would be asked to recall events they had experienced in their own lives that involved pairs of objects, for example, a table and a glass of wine, or a fish and an aquarium.
(C) This is a psychology question that belongs to the category "making sense of the environment" and requires knowledge about types of memory storage. The correct answer is C. Declarative or explicit memory is a long-term storage that holds factual information that can be consciously recalled at any moment in time. An example would be the names of the planets in the solar system as learned during childhood. Implicit memory stores motor knowledge, such as learned dance choreography steps, that often cannot be consciously recalled. A test that involves memorizing stimuli such as words and immediately recalling them would probably be concerned with either short-term or working memory. A test inspecting memories from one's own experience that involve pairs of objects would probably be concerned with episodic memory.
Behavior that would be socially unacceptable at other times, for example, excessive drinking, urinating in public, or overt sexual behavior, is accepted in many places during Mardi Gras (Carnival) season. What perspective would Émile Durkheim apply to this? (A) He would see Mardi Gras as a temporal reversal of front stage and back stage. The performance that would usually happen in the hidden space, in back of the stage, is allowed out in the open temporarily, during the pre-Lenten season. (B) He would describe Mardi Gras as a case of "opium of the people," distracting them from political and structural issues of power, control, and oppression. (C) He would draw upon his concept of the safety valve. Durkheim argued that Mardi Gras presents a relatively harmless way for people to express discontent and resistance. (D) For Durkheim, Mardi Gras would have to be understood as a dialectic between feast and fast. He would point at the rituals and rules of Christian tradition. Pre-Lenten excess would be considered necessary in order for people to find the following fasting period up until Easter more bearable.
(C) This sociology question requires knowledge about "social processes that influence human behavior," more specifically about Durkheim's notion of deviance. Durkheim looked at deviance with a focus on its function in society. The function of deviance is to show people what is right and wrong in society. It is a label that is given by the other members of society. During Mardi Gras/Carnival some forms of deviance are not labeled as bad or undesirable and are therefore allowed and performed in public. For him events such as Mardi Gras would act as a safety valve in society. Safety valves are social institutions that allow "letting off steam" without any severe consequences for the larger society. These institutions would help to reduce tensions. Other safety valve institutions can range from sports to strikes, gambling, and prostitution. These behaviors cannot be completely eradicated from society and thus become tolerated on special occasions. Front stage and backstage refers to Erving Goffman's concept of dramaturgy and does not apply to Durkheim's views on Mardi Gras. Durkheim also would not be primarily interested in the dialectics between fast and feast. Furthermore, Durkheim would not be concerned with dialectic processes; this would be Marxist thinking. "Opium of the people" is a concept that is also related to Marxist approaches.
The pentapeptide ANLEQ has been evaluated by a team of researchers. A single-point mutation was applied resulting in a change of the amino acid residue glutamine to arginine. At physiological pH, the new pentapeptide in solution would be expected to carry approximately: (A) a net positive charge. (B) a net negative charge. (C) a net neutral charge. (D) a variable charge.
(C) To estimate the overall charge of ANLEQ at physiological pH (approx. 7.4): Alanine (A, ala, hydrophobic) - Asparagine (N, asn, polar uncharged) - Leucine (L, leu, hydrophobic) - Glutamate (E, glu, negatively charged at physiological pH (-COO- side chain with pKa 4.5) - Glutamine (Q, gln, polar uncharged). Thus the overall charge is negative one. The new peptide sequence would be ANLER (be careful when differentiating between glutamate/glutamic acid and glutamine). Thus we change Glutamine (Q, gln, polar uncharged) to Arginine (R, arg, positive), thus the pentapeptide would be approximately neutral.
The value of the water dissociation constant Kw varies with temperature. Its value is normally given as 1.00 x 10^-14 mol^2 dm^-6 at room temperature but 1.00 x 10^-13 mol^2 dm-6 at 60 °C. What is the pH of pure water at 60 °C? (A) Equal to 7.0 thus the water is neutral (B) Less than 7.0 thus the water is acidic (C) Less than 7.0 but the water is basic (D) Less than 7.0 but the water is neutral
(D) It is not necessary to calculate anything to solve this problem but we will go through the steps. The dissociation of water (note carefully that the ratio of the products is 1:1; also keep in mind that this is the basis of the neutrality of pure water: acid units = base units): H2O + H2O <-> H3O++ OH- The expression for the self-ionization of water or the water dissociation constant: Kw= [H3O+][OH-] = [H+][OH-] At room temperature, keeping in mind that the dissociation of the ions is 1:1, we get: 10-14 = [H+][OH-] = [H+]^2 And so [H+] = 10^-7 and then -log[H+] = 7 = pH Doing the identical math but using Kw = 10^-13 yields a pH of 6.5 BUT because the ratio of the ions is still 1:1 (if not, you would not have done the calculation) thus it must be neutral.
ORNITHINE CARBAMOYLTRANSFERASE (argF gene) - converts ornithine/carbamoylphosphate to citrulline ARGININOSUCCINATE SYNTHASE (argG gene) - converts citrulline to argininosuccinate ARGININOSUCCINASE (argH gene) - converts argininosuccinase to arginine Figure 1: A synthesis pathway for the amino acid arginine. Each gene in italics in the diagram produces one enzyme necessary for the synthesis of this essential amino acid required for growth. Mutant strains P and Q P: nothing = (-), ornithine = (-), or citrulline = (-), argininosuccinate = (+), arginine = (+) Q: nothing = (-), ornithine = (-), or citrulline = (-), argininosuccinate = (+), arginine = (+) Table 1: Growth response of mutant strains in "minimal" media with supplements (ornithine, citrulline, argininosuccinate, and arginine) as indicated. Strain growth is indicated by (+) and no strain growth is indicated by (-). According to the information provided, a conclusion that can be made with certainty is that neither mutant strain P nor Q have the defective enzyme: (A) carbamoyltransferase. (B) argininosuccinate synthase. (C) argininosuccinase. (D) None of the above enzymes are defective in either mutant strain P nor Q.
(C) You should recognize that enzymes typically end with -ase and so you can see that the figure provided indicates the 3 enzymes that are catalysts for the three reactions as shown. Now let's reinterpret the question: if neither P nor Q have a defective enzyme X, then both P and Q must have a functioning enzyme X (the other interpretation is that they have no enzyme but that is not consistent with the data in the table provided). In other words, "Which of the answer choices corresponds to an enzyme that is fully functional in strains P and Q?" The information in the table shows a (+) symbol in the last two columns indicating that both P and Q are able to convert argininosuccinate to arginine (see Table 1). This necessarily means that both P and Q have a functioning enzyme argininosuccinase (see Figure 1).
Counselors who experience the cumulative effects of strain and exhaustion from hearing the stories of violence of victims of domestic violence over time are suffering from a phenomenon named: (A) learned helplessness. (B) acute stress. (C) compassion fatigue. (D) post-traumatic stress syndrome.
(C) is correct. Compassion fatigue (or secondary victimization, or secondary traumatic stress disorder) refers to the emotional disruption caused in helpers by listening repeatedly to clients' narratives about horrific and traumatic events. The accumulation of secondary distress generates a state that resembles post-traumatic stress disorder. Its symptoms include: cognitive intrusion, avoidance, negative affect, anhedonia, anxious arousal, and dysphoric arousal. Although it was not identified as a separate disorder in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), research about it is ongoing and regards such experience as an occupational hazard with psychological and functional consequences.
How would diffusion of innovations theory attempt to explain why African American women get fewer mammograms compared with their Caucasian female counterparts? (A) African Americans tend to feel stigmatized when they seek medical treatment. (B) It is possible that African American females experience multiple role conflicts and therefore, they are more likely to relegate their personal needs to the needs of their family. (C) It is possible that there is a pervasive distrust of medical personnel in African-American communities. (D) Religiosity is a vital ingredient in the fabric of African American lives, and therefore, they will initially opt to see faith healers for their health.
(C) is correct. Everett Rogers' (1962) cultural diffusion of innovations model describes how the diffusion of new ideas can spread directly or indirectly across society. He posited that communities which were more conservative and unwilling to adopt new technology would be slow to accept innovative ideas. Distrust of medical personnel would be a driver for that unwillingness to change.
What is the relationship between suicide rates and social change according to the sociologist Emile Durkheim? (A) A higher suicide rate leads to more social change. (B) A higher suicide rate leads to less social change. (C) Social change leads to suicide rates going up. (D) Social change leads to suicide rates going down.
(C) is correct. In association with his observational study, Durkheim developed a typology of suicide that ascribed this behavior to the unsettling effects of social change. That is, for him, social change caused suicide. The greater social change was, the higher suicide rates were. A. This is incorrect. According to Durkheim, a change in suicide rates has no effect on social change. B. This is incorrect. According to Durkheim, suicide has no effect on social change. D. This is incorrect. According to Durkheim, social changelea ds to suicide rates going up, rather than going down.
When interpreting the data about lifetime prevalence rates of physical assault, as experienced by women in the four different racial minority groups, which of the following sociological theories is least helpful at explaining found differences? (A) Attribution theory (B) Feminist theory (C) Social desirability theory (D) Conflict theory
(C) is correct. Social desirability is more adequately described as a mechanism, phenomenon, or bias - not as a social theory. It is defined as the phenomenon whereby individuals in a research study will attempt to present themselves in a more favorable light. In studies involving sensitive topics (e.g., racial opinions) or which are utilized for sensitive purposes (e.g., job applications), there is a chance respondents will distort or fake factual information so as to be more favorably perceived. Secondly, social desirability is not commonly used to explain such differences. Moreover, presently, there is no evidence of social desirability affecting differently different racial groups. That is, theoretically speaking, it could affect equally every group. Thus, this is the least helpful theory at explaining found differences.
Which of the following is most consistent with the information in the passage including Figure 1 and Figure 2? (A) Hemoglobin has more affinity to oxygen than to carbon monoxide. (B) Hemoglobin has more affinity to carbon dioxide than to carbon monoxide. (C) Carbon monoxide likely shifts the O2-Hb dissociation curve to the right. (D) None of the above.
(D) Checking the units carefully, and even within the PCO2 values, it is clear that the Hb affinity to CO is a couple of hundred times greater than to oxygen. (Side note: "Carbon monoxide has 210 times greater affinity for hemoglobin than oxygen") "Answer choice C is incorrect because carbon monoxide (CO) actually shifts the oxygen dissociation curve (O2-Hb) to the left (instead of right). As CO has a much higher affinity to hemoglobin, it does not get displaced easily once bound to hemoglobin and hence, reducing oxygen release capability. When the hemoglobin circulates to the tissues, less oxygen is available for off-loading and results in hypoxia."
What would the freezing point in Kelvin of a solution which is 0.50 molal in sucrose and 0.50 molal in acetic acid be?(Kf of water = 2.0 °C mol-1 and freezing point of water = 0 °C) (A) -1.0 K (B) -2.0 K (C) 272 K (D) 271 K
(D) From the equation Tf = Kfm, Tf = (2.0 °C mol-1)(0.5 molal + 0.5 molal) = 2.0 °C. Therefore, the freezing point of this solution is 0 °C - 2 °C = -2 °C = (273 - 2) K = 271 K. {Recall: acetic acid is a weak acid thus relatively very little dissociates; CHM 6.1, 6.6}
The human kidney can be damaged from a number of causes resulting in a patient's inability to filter toxins (i.e. urea) from the body which could result in death. Complete kidney failure is usually first treated with dialysis which "cleans" the blood. Figure 1: Dialysis. The "dialyzer" is a glass container that has 3 main components: (1) blood percolating through to be cleaned; (2) a dividing membrane; and (3) the dialysate. The latter is liquid containing chemicals used to draw fluids and toxins out of the bloodstream and supply electrolytes and other chemicals to the bloodstream. (kidney.niddk.nih.gov) Considering the information provided, which of the following is NOT consistent with the process of dialysis? (A) The membrane in the dialyzer separating the dialysate and the blood must be semipermeable. (B) The concentration of toxins in the dialysate must increase during dialysis. (C) The concentration of glucose and vital minerals in the dialysate must be similar to that of the patient's blood. (D) Excessive minerals and toxins cross the membrane in the dialyzer by osmosis.
(D) On the Surface: Dialysis only refers to the transfer of the solute (diffusion), while the transfer of the solvent is called osmosis.
Neurons and the propagation of an action potential down the axon can be studied using a simple electrical circuit. A battery represents the sodium-potassium pump which maintains the concentration gradient across the membrane. Because the membrane acts as an insulator separating the charge build-up on the outside and inside of the neuron, it is modeled as a capacitor with capacitance C = 1 μF/cm^2. If the voltage changes from -40 mV to 70 mV during an action potential, how much charge per surface area crosses the axon membrane during the action potential? (A) 0.1 nC/cm^2 (B) 1.1 nC/cm^2 (C) 11 nC/cm^2 (D) 110 nC/cm^2
(D) The charge flowing across the membrane can be related to the action potential voltage and membrane capacitance using Q = CV. The capacitance is given in the passage (1st paragraph, "modeled as a capacitor with capacitance..."): C = 1 μF/cm2. Putting the two together: Q = (1 μF / cm^2)*(110 mV) = (1 * 10^-6 F / cm^2) * (110 * 10^-3 V) = 110 * 10^-9 F*V/cm^2= 110 * 10-9 C/cm2 = 110 nC/cm^2 Therefore, answer choice D is the correct answer.
A longitudinal environmental study investigated the relationship between single-family home design and women's social roles in the last 80 years in the U.S. According to gender studies literature, the study would have more likely found evidence that: (A) nowadays women more often experience role conflict. This was associated with the clearer separation of the functions of each room. (B) nowadays women more often experience role playing. This was associated with the use of large, ample rooms. (C) nowadays women more often experience role taking. This was associated with an increase in the frequency with which women are responsible for designing their family rooms. (D) nowadays women more often experience role strain. This was associated with the inclusion of multifunction rooms.
(D) This is a psychology question covered by the category "social interactions," which specifies that knowledge about elements of social interaction such as role conflict and role strain should be possessed. The correct answer is D. Gender roles amount to socially and culturally determined expectations and beliefs about the experiences of men and women. Gender role strain is a concept used to describe how sometimes multiple assigned roles, in this case to women, can create tension and conflict. For example, women may be expected to nurse their young children; their gender role would thus involve taking care of infants. In regard to professional issues, women's role is known to have changed in the past decades. They are generally expected to hold jobs, principally in most sociocultural Western contexts such as the U.S. Evidence also shows that they may experience difficulties fulfilling both roles, that is, experience role strain. It is conceivable that home designs have also changed in recent decades with the goal of helping families deal with role strain. For example, spaces that allow for multitasking professional and family duties, such as including office spaces near nursing rooms, could have become more common. Gender role conflict theory states that the roles assigned to each gender can have negative consequences for individuals. This theory is more often applied to men, not women. James O'Neil, one of this theory's leading researchers, claims that restrictive definitions of masculinity can, for instance, damage men's well-being, restrict their emotionality and affectionate behavior, and create conflicts between men's work and family relations. Although gender role conflict could be applied to understanding and studying women's role strain, it seldom is; it is also not commonly defined as a women's problem. Thus conclusions regarding the relationship between women's role conflict changes and house design changes would be unlikely. Role taking is a mechanism that allows people to adopt the perspectives of others. In psychology, the term role playing is often used to refer to the acting out of certain social roles or characters. None of these psychological mechanisms are commonly understood as prone to sociocultural longitudinal changes. Hence conclusions regarding how changes in the use of role taking or role playing mechanisms are related to home design changes would be unlikely.
Consider Figure 1 which demonstrates the oxygen dissociation curves for the hemoglobin (Hb) in muscle capillaries for various mammals (dissociation curve shifts to the right with smaller mammals). What conclusion can be drawn? (A) The hemoglobin of smaller mammals will retain oxygen at a lower pO2 than that of larger mammals. (B) The activity of the mammal is directly proportional to the ability of its hemoglobin to release oxygen. (C) The hemoglobin of larger mammals will release oxygen at a higher pO2 that that of smaller mammals. (D) The size of the mammal is inversely proportional to the ability of its hemoglobin to release oxygen.
(D) is correct. Considering your options: (A) Take a look at the oxygen partial pressure (= oxygen concentration = pO2) of a small mammal (i.e. a mouse, number 8 in Figure 1) compared to a large mammal (i.e. a horse, number 2 in Figure 1). At an oxygen partial pressure of 40 mm Hg, the mouse only is at around 30% saturation but the horse is around 80% saturation meaning that the larger animal retains oxygen better at a given oxygen concentration, no matter what the value is towards the mid to lower end of the scale, thus answer choice A is incorrect. (B) We have no information about the activity of the different mammals. (C) From the scale provided, consider the relatively high value of 80 mm Hg and we see that large mammals (elephant, horse, man) are at 100% saturation so they are not releasing any oxygen, but smaller mammals (rat, mouse) are at 80% so they have released some oxygen. Thus answer choice C is incorrect because smaller mammals release oxygen at higher oxygen concentrations that do larger mammals. (D) We have just established that smaller mammals release oxygen at higher oxygen concentrations that do larger mammals, this this is an inverse relationship. Another way to say this is that smaller mammals have Hb with a lower affinity towards oxygen (this means oxygen is less apt to saturate the Hb of smaller mammals which permits increased delivery of oxygen to the tissues of these organisms with relatively high metabolism).
Which of the following methodological procedures would NOT help to assure that the findings in Table 1 allow drawing valid and reliable conclusions about differences in victimization incidence across race groups? (A) Verify whether the population in the US shows or does not show the same proportion of races as that found for the study illustrated in Table 1. (B) Create equal sample sizes and test whether group differences are significant, like through ANOVA. (C) Verify whether the samples per condition are or are not fairly equivalent in term of demographic characteristics, such as age, place of residence, and employment status. (D) Verify whether race groups are or are not strongly and significantly correlated to the number of victimization incidents.
(D) is correct. Correlations are association tests that can be applied only when there are at least ordinal variables under study. The study illustrated in Table 1 includes one at least ordinal variable: amount of victimization incidents. This is a quantitative variable. However race groups are a nominal variable. Thus, correlations could not be applied to help to assure that valid and reliable conclusions about race group differences in victimization incidence can be drawn.
As a result of the crossover in the previous question, which of the following gene sequences is LEAST supported by the information provided? (A) cdefghik*klm (B) mlk*jihGF*KLM (C) MLK*FGHIJEDC (D) All 3 are equally probable.
(D) is correct. For answer choice C, note that CDEJIHGF*KLM from the previous question is the same as MLK*FGHIJEDC.Side Note: Like crossovers, inversion loops do not alter the overall amount of genetic material; however, they reduce the number of recombinant products (and recombination frequency) in the progeny of heterozygotes. Here is a third-party video (not an actual party!) showing the entire process, step by step, with G-H cross and inverted loop (approx. 13 minutes): https://www.youtube.com/watch?v=Z13o9KGltWA
How must promoters of health behaviors communicate with a high-context culture like the Asian? (A) Communicate directly with participants, using informal language mostly, and with little emphasis on nonverbal cues (B) Assume what is being said is what is actually meant (C) Get to the point of the discussion as quickly as possible (D) Employ formal language, rely on nonverbal cues, and be comfortable with silences
(D) is correct. High-context cultures are those that have communication styles that rely on shared experiences, implicit messages, relational aspects, and nonverbal cues. That is, people from high context cultures tend to listen by focusing on the tone and how something was communicated, say more with fewer words, and intentionally make use of silence. Much is understood from manner, status, physical context, relationship, and/or shared background without use of words. They will also often take time to think things through before making a response. Conversely, lower-context cultures (e.g., America) are less comfortable with long pauses, use words to fill up silences, and communicate everything explicitly.
Vaccines are used to combat and prevent the spread of epidemics. When vaccines are included in the model, what is the basic reproduction number for Ebola (R = 2-3) if 50% of the population is vaccinated and the vaccine works perfectly? (A) 3-4 (B) 2-3 (C) 1-1.5 (D) 0.5-1
If half of the population is vaccinated, that means an infected person will come into contact with only half as many susceptibles compared to a non-vaccinated population. Since R is the number of new cases generated by one infected, decreasing the contact rate of the infected will also decrease the number of cases they generate with the two being proportional. From Table 1, the basic reproduction number for Ebola is 2-3. If 50% of the population is vaccinated, then the number of susceptibles has decreased by 50%, causing R to decrease by 50%. So the basic reproduction number with 50% vaccinations is 1-1.5.
The frequency of vibration of a diatomic system composed of two atoms with masses m1 and m2 is given by the following equation. ∨ = (1/2π) x √(k/m) where ∨ = frequency of vibration, k = force constant of the bond between two atoms, and m = (m1 + m2)/(m1m2). Two atoms of masses 2 units each are joined by a chemical bond of force constant, k = 4 units. What is the value for the frequency of vibration? (π = pi) (A) 1/π (B) 1/√2π (C) √2/π (D) impossible to determine without more data.
M = (2 + 2)/(2 x 2) = 4/4 = 1 Using frequency = (1/2π) x √(k/M) Frequency = (1/2π) x √(4/1) = (1/2π) x 2 Frequency = 1/π Hz
The following pair of chromosomes is present in an inversion heterozygote with * denoting the centromere. Note that each of the following genes is considered vital, regardless of the order. CDEJIHGF*KLM and cdefghij*klm If a crossover event takes place between genes G and H in meiosis, based on the information provided, which of the following statements would most likely be true regarding the products (gamete chromosomes)? (A) The gametes will not be viable. (B) Roughly 50% will contain duplicated genes. (C) Roughly 50% will have 2 centromeres while the rest will have no centromeres. (D) The gametes would be the result of a pericentric cross over.
On the Surface: The results . . . - 2 unchanged and thus viable gametes: CDEJIHGF*KLM and cdefghij*klm - 2 not viable with duplications and missing genes, no centromere and an extra centromere: mlk*jihGF*KLM cdefgHIJEDC Going Deeper: From Figure 2a, the inversion heterozygote will form an inversion loop at synapsis. The synapsis only occurs between homologous loci and the loop spans the region of the inversions. Thus a paracentric inversion with a crossover in the loop yields: 1) a parental chromatid; 2) the other parental chromatid; 3) a dicentric chromatid; 4) an acentric chromatid.
Six Basic Types of Enzymes
Oxidoreductases - redox reactions Transferases - the transfer of groups of atoms Hydrolases - hydrolysis Lyases - additions to a double bond, of the formation of a double bond Isomerases - the isomerization of molecules Ligases or synthetases - the joining of two molecules
