Medical Tests MCAT-TEST Online Practice Questions and Exam Preparation

Medical Tests MCAT-TEST Online Questions & Answers

• Question 41:

  Which option is something that could be detected by a proprioceptive sensor?

  A. temperature change
  B. light
  C. the position of the body
  D. pain
  C. the position of the body

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  Explanation/Reference:

  Proprioceptive sensors are found in the muscles and connective tissue and can detect the position of the body. The other options are detected by somatic and skin sensors.

• Question 42:

  Hemophilia is a genetically inherited disease that causes the synthesis of an abnormal clotting factor. As a result, hemophiliacs bleed excessively from the slightest injury. The figure below is a partial pedigree for the hemophilia trait in Queen Victoria's descendants. The pedigree indicates no history of hemophilia for either parent prior to the F1 generation.

  

  Which of the following best explains why Louis IV was NOT a hemophiliac?

  A. His son Frederick was a hemophiliac.
  B. He did not inherit the gene for hemophilia from his mother.
  C. His father-in-law, Albert, was not a hemophiliac.
  D. Only females can be carriers of the gene for hemophilia.
  B. He did not inherit the gene for hemophilia from his mother.

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  Explanation/Reference:

  A male can inherit an X-linked trait only from his mother, since he inherits his one X chromosome from her. Thus, Louis IV, who was normal, did not inherit the gene for hemophilia from his mother, who is not shown on the pedigree. Remember, Louis IV was not a blood relative of the Queen, he was her son-in-law. Choice A is incorrect, since Louis IV's son, Frederick, has hemophilia because he inherited the gene from his mother, who was a carrier (although we don't know her name). Besides, whether Louis IV's children were hemophiliacs, carriers, or normal, is irrelevant to the discussion of why Louis himself was normal. Choice C is incorrect because Albert was not a blood relative of Louis IV, so Albert's genotype is independent of Louis' genotype. As for choice D, while it is true that only females can be carriers of the hemophilia gene, or of any X-linked gene for that matter, this does not answer the question.

• Question 43:

  Arginine is one of the 20 most common natural amino acids. Most healthy people do not need to supplement with arginine because the body usually produces sufficient quantities. The pathway for arginine synthesis was studied using cells from a red bread mold. This natural form of arginine is illustrated below.

  

  The red bread mold Neurospora crassa grows well on a cultural plate with "minimal" medium which is a fluid containing only a few simple sugars, inorganic salts, and vitamin. Neurospora that grows normally in nature (wild type) has enzymes that convert these simple substances into the amino acids necessary for growth. Mutating any one of the genes that makes an enzyme can produce a Neurospora strain that cannot grow on minimal medium. The mutant would only grow if the enzyme product were to be added as a supplement. On the other hand, if a "complete" medium is provided, containing all required amino acids, then Neurospora would grow, with or without mutation.

  

  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.

  

  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 (-). Consider tetrapeptides containing 2 equivalents each of the natural forms of arginine and proline. How many different linear tetrapeptides can be synthesized?

  A. 2
  B. 3
  C. 6
  D. 8
  C. 6

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  Explanation/Reference:

  Keep in mind when considering linear polypeptides that there must be an amino end and a carboxyl end, thus RRPP is a different molecule than PPRR (Note the IUPAC official abbreviations. Arginine is abbreviated as arg or R, proline is

  abbreviated as pro or P). Thus, there are 6 possibilities: RRPP, RPPR, RPRP, PPRR, PRPR, PRRP.

  Side Notes. If you have a statistics background, you can do "4 choose 2" = 4!/2!2! = (4)(3)(2)(1)/4 = 24/4 = 6.

  The ability to form multiple H-bonds make arginine ideal for binding negatively charged groups. For this reason, arginine prefers to be on the outside of proteins, where it can interact with the polar environment.

  A tetrapeptide is an oligopeptide since it only consists of four amino acids joined by peptide bonds. Tetrapeptides can be pharmacologically active including affinity to receptors involved in protein-protein signaling. Both linear and cyclic

  tetrapeptides can be found in nature.

• Question 44:

  Based on the table below, what is the cell voltage for the following reaction?

  

  A. –1.33 V
  B. 1.99 V
  C. 1.33 V
  D. 1.62 V
  D. 1.62 V

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  Explanation/Reference:

• Question 45:

  Which one of the following is electron deficient?

  A. NH3
  B. PH3
  C. BCl3
  D. PCl3
  C. BCl3

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  Explanation/Reference:

• Question 46:

  The process of depolarization triggers the cardiac cycle. The electronics of the cycle can be monitored by an electrocardiogram (EKG). The cycle is divided into two major phases, both named for events in the ventricle: the period of ventricular contraction and blood ejection, systole, followed by the period of ventricular relaxation and blood filling, diastole.

  During the very first part of systole, the ventricles are contracting but all valves in the heart are closed thus no blood can be ejected. Once the rising pressure in the ventricles becomes great enough to open the aortic and pulmonary valves, the ventricular ejection or systole occurs. Blood is forced into the aorta and pulmonary trunk as the contracting ventricular muscle fibers shorten. The volume of blood ejected from a ventricle during systole is termed stroke volume.

  During the very first part of diastole, the ventricles begin to relax, and the aortic and pulmonary valves close. No blood is entering or leaving the ventricles since once again all the valves are closed. Once ventricular pressure falls below atrial pressure, the atrioventricular (AV) valves open. Atrial contraction occurs towards the end of diastole, after most of the ventricular filling has taken place. The ventricle receives blood throughout most of diastole, not just when the atrium contracts.

  Figure 1: Electronic and pressure changes in the heart and aorta during the cardiac cycle.

  

  According to Fig. 1, the opening of the aortic and pulmonary valves is NOT associated with:

  A. ventricular systole.
  B. a rise and fall in aortic pressure.
  C. a drop and rise in left ventricular volume.
  D. the third phase of the cardiac cycle.
  C. a drop and rise in left ventricular volume.

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  Explanation/Reference:

  Close analysis of Figure 1 (compare to previous questions especially Q2) reveals that during the period that the aortic and pulmonary valves are OPEN, the curve for left ventricular volume drops (= decreases) but does not rise (= increase).

• Question 47:

  DNA polymerase creates new DNA by adding complimentary nucleotides to a template strand from the original double-stranded DNA. If a section of the template strand had a ratio of 3:2 of A:T bases, what is the ratio of A:T in the newly synthesized complimentary strand of DNA?

  A. 3:2
  B. 1:1
  C. 2:3
  D. It cannot be determined.
  C. 2:3

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  Explanation/Reference:

  DNA polymerase matches complimentary bases to each base in the template strand. If the template strand has an A:T ratio of 3:2, then the complimentary strand must have an A:T ratio of 2:3 in order to match the complimentary bases with their correct paired nucleotide. That is, each A in the original strand will be matched with a T and vice versa.

  A: 3:2, incorrect. This would be true if the complimentary strand matched A:A and T:T.

  B: 1:1, incorrect. Complimentary strand bases are paired in the same ratio, but with T in the place of A.

  C: 2:3, correct.

  D: it cannot be determined, incorrect. A:T must be matched with T:A on the complimentary strand.

• Question 48:

  Which metal have least tendency to form a positive ion?

  A. Aluminum
  B. Calcium
  C. Iron
  D. Sodium
  C. Iron

• Question 49:

  The mind, just like the body, has its needs. The needs of the body are the foundations of society; those of the mind are its amenities. While government and laws provide for the safety and well-being of men when they gather together, the sciences and the arts, which are less despotic but perhaps more powerful, spread garlands of flowers over the iron chains that bind them, stifle in them the sense for that original liberty for which they seem to have been born, cause them to love their own enslavement, and turn them into so-called "civilized people." Necessity raised thrones; the sciences and the arts have strengthened them. O earthly powers: cherish talents and protect those who cultivate them. O civilized people, cultivate them: you happy slaves owe to them that delicate and refined taste of which you are so proud, that gentleness of character and urbanity of manner which make relations among you so amiable and easy -- in other words, that semblance of all the virtues, none of which you actually possess... ...How pleasant it would be to live among us, if our external appearance were always a reflection of what is in our hearts, if decency were virtue, if our maxims served as our rules, and if true philosophy were inseparable from the title of philosopher! But so many qualities are seldom found together, and virtue hardly ever walks in such great pomp. Richness of adornment may be the mark of a man of taste, but a healthy, robust man is known by other signs: it is beneath the rustic clothes of a farmer, and not the gilt of a courtier, that strength and vigor of the body will be found. Ornamentation is just as foreign to virtue, which is the strength and vigor of the soul. The good man is an athlete who prefers to compete in the nude: he disdains all those vile ornaments which would hinder the use of his strength, ornaments which were for the most part invented only to hide some deformity. Before art had molded our manners and taught our passions to speak an affected language, our customs were rustic but natural, and differences in conduct revealed clearly differences in character. Human nature, basically, was no better, but men found security in being able to see through each other easily, and this advantage, which we no longer appreciate, spared them many vices. Now that more subtle refinements and more delicate taste have reduced the art of pleasing to set rules, a base and deceptive uniformity prevails in our behavior, and all minds seem to have been cast in the same mold. Incessantly politeness and propriety make demands on us, and incessantly we follow usage but never our own inclinations. We no longer dare to appear as we are, and under this perpetual constraint, the men who form this herd called society, when placed in the same circumstances, will all act similarly unless stronger motives direct them to do otherwise. Therefore we will never know well those with whom we deal, for to know our friends we will have to wait for some crises to arise -- which is to say that we will have to wait until it is too late, as it is for these very crises that it is essential to know one's friends well. What vice would not accompany this uncertainty? No more sincere friendships, no more genuine esteem, no more well-based confidence. Suspicion, offenses, fears, coldness, reserve, hatred and betrayal will constantly hide under the same false veil of politeness, under that much touted urbanity which we owe to the enlightenment of our times. The name of the Master of the Universe will no longer be profaned by swearing, but insulted by blasphemies that will not offend our scrupulous ears. Men will not boast of their own merits, but belittle those of others. An enemy will not be crudely insulted, but adroitly slandered. National hatreds will die, but so will patriotism. A dangerous skepticism will take the place of the scorning of ignorance. Some excesses will be forbidden, some vices dishonored, but others will be dignified with the name of virtues, and one must either have them or feign them. Let those who want to praise the sobriety of the sages of our time do so; as for me, I see in it only a refinement of intemperance that is as unworthy of my praise as their hypocritical simplicity.

  According to the tone and content of the passage, which statement best reflects the author's opinion of the purpose of the sciences and the arts?

  A. They are necessary for the safety and well-being of mankind.
  B. They interfere with responsive action and honest communication.
  C. They reinforce the sense of "original liberty" that is present in all men.
  D. They have molded our reactions into predictable but essential forms.
  B. They interfere with responsive action and honest communication.

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  Explanation/Reference:

  The primary argument is that man has become burdened by politeness, which springs from devotion to the graces. He implies that a "natural" man, who responded simply and plainly and with honesty, is preferable because his character is

  known from the outset.

  A is not true -- government and laws are necessary for the safety and well-being of mankind; C is incorrect because the arts cloud over the "original liberty" that each man is provided with; D is incorrect because the author believes the

  molding is absolutely not essential.

• Question 50:

  When Gwendolyn Brooks published her first collection of poetry A Street In Bronzeville in 1945 most reviewers recognized Brooks' versatility and craft as a poet. Yet, while noting her stylistic successes few of her contemporaries discussed the critical question of Brooks' relationship to the Harlem Renaissance. How had she addressed herself, as a poet, to the literary movement's assertion of the folk and African culture, and its promotion of the arts as the agent to define racial integrity? The New Negro poets of the Harlem Renaissance expressed a deep pride in being Black; they found reasons for this pride in ethnic identity and heritage; and they shared a common faith in the fine arts as a means of defining and reinforcing racial pride. But in the literal expression of this impulse, the poets were either romantics, or realists and, quite often within the same poem, both. The realistic impulse, as defined best in the poems of McKay's Harlem Shadows (1922), was a sober reflection upon Blacks as second class citizens, segregated from the mainstream of American socio-economic life, and largely unable to realize the wealth and opportunity that America promised. The romantic impulse, on the other hand, as defined in the poems of Sterling Brown's Southern Road (1932), often found these unrealized dreams in the collective strength and will of the folk masses. In comparing the poems in A Street in Bronzeville with various poems from the Renaissance, it becomes apparent that Brooks brings many unique contributions to bear on this tradition. The first clue that A Street In Bronzeville was, at its time of publication, unlike any other book of poems by a Black American is its insistent emphasis on demystifying romantic love between Black men and women. During the Renaissance, ethnic or racial pride was often focused with romantic idealization upon the Black woman. A casual streetwalker in Hughes' poem, "When Sue Wears Red," for example, is magically transformed into an Egyptian Queen. In A Street In Bronzeville, this romantic impulse runs headlong into the biting ironies of racial discrimination. There are poems in which Hughes, McKay and Brown recognize the realistic underside of urban life for Black women. But for Brooks, unlike the Renaissance poets, the victimization of poor Black women becomes not simply a minor chord but a predominant theme. ...Brooks' relationship with the Harlem Renaissance poets, as A Street in Bronzeville ably demonstrates, was hardly imitative. As one of the important links with the Black poetic tradition of the 1920s and 1930s, she enlarged the element of realism that was an important part of the Renaissance world-view. Although her poetry is often conditioned by the optimism that was also a legacy of the period, Brooks rejects outright their romantic prescriptions for the lives of Black women. And in this regard, she serves as a vital link with the Black Arts Movement of the 1960s that, while it witnessed the flowering of Black women as poets and social activists as well as the rise of Black feminist aesthetics in the 1970s, brought about a curious revival of romanticism in the Renaissance mode.

  With which one of the following statements about A Street in Bronzeville would the author most likely agree?

  A. It further developed the realistic impulse of the Harlem Renaissance tradition.
  B. It was marred by an optimism inherited from Harlem Renaissance poetry.
  C. It completely rejected the poetic conventions of the Harlem Renaissance.
  D. It was the first significant work of a Black feminist writer.
  A. It further developed the realistic impulse of the Harlem Renaissance tradition.

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  Explanation/Reference:

  Choice A notes the contribution Brooks made to the realistic nature of Black poetry. Choice B is right in attributing optimism to Brooks' poetry (line 51) but wrong in alleging that the author would call that a "marring" influence. Inferably, optimism is one of the offshoots of the ethnic pride that both the Renaissance and Brooks shared. Choice C goes too far in the other direction. To "enlarge" (line 48) upon a tradition is far from "completely rejecting" it. Choice D is a conclusion whose scope goes beyond the passage. Any number of Black feminist writers could have preceded Brooks' appearance in 1945.