Medical Tests MCAT-TEST Online Practice Questions and Exam Preparation

Medical Tests MCAT-TEST Online Questions & Answers

• Question 591:

  Which of the following species will form the most stable radical?

  

  A. Option A
  B. Option B
  C. Option C
  D. Option D
  A. Option A

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  Explanation/Reference:

  The stability of free radicals decreases from tertiary>secondary>primary>methyl. Choice A is the only choice that can form a tertiary radical. Choices B, C, and D will form secondary radicals.

• Question 592:

  ...Until last year many people -- but not most economists -- thought that the economic data told a simple tale. On one side, productivity--the average output of an average worker -- was rising. And although the rate of productivity increase was very slow during the 1970's and early 1980's, the official numbers said that it had accelerated significantly in the 1990's. By 1994 an average worker was producing about 20 percent more than his or her counterpart in 1978. On the other hand, other statistics said that real, inflation- adjusted wages had not been rising at anything like the same rate. In fact, some of the most commonly cited numbers showed real wages actually falling over the last 25 years. Those who did their homework knew that the gloomiest numbers overstated the case.... Still, even the most optimistic measure, the total hourly compensation of the average worker, rose only 3 percent between 1978 and 1994.... ...But now the experts are telling us that the whole thing may have been a figment of our statistical imaginations.... a blue-ribbon panel of economists headed by Michael Boskin of Stanford declared that the Consumer Price Index [C.P.I.] had been systematically overstating inflation, probably by more than 1 percent per year for the last two decades, mainly failing to take account of changes in the patterns of consumption and improvements in product quality.... ...The Boskin report, in particular, is not an official document -- it will be quite a while before the Government actually issues a revised C.P.I., and the eventual revision may be smaller than Boskin and his colleagues propose. Still, the general outline of the resolution is pretty clear. When all the revisions are taken into account, productivity growth will probably look somewhat higher than it did before, because some of the revisions being proposed to the way we measure consumer prices will also affect the way we calculate growth. But the rate of growth of real wages will look much higher -- and so it will now be roughly in line with productivity, which will therefore reconcile numbers on productivity and wages with data that show a roughly unchanged distribution of income between capital and labor. In other words, the whole story about workers not sharing in productivity gains will turn out to have been based on a statistical illusion. It is important not to go overboard on this point. There are real problems in America, and our previous concerns were by no means pure hypochondria. For one thing, it remains true that the rate of economic progress over the past 25 years has been much slower than it was in the previous 25. Even if Boskin's numbers are right, the income of the median family -- which officially has experienced virtually no gain since 1973 -- has risen by only about 35 percent over the past 25 years, compared with 100 percent over the previous 25. Furthermore, it is quite likely that if we "Boskinized" the old data -- that is, if we tried to adjust the C.P.I. for the 50's and 60's to take account of changing consumption patterns and rising product quality -- we would find that official numbers understated the rate of progress just as much if not more than they did in recent decades.... ...Moreover, while workers as a group have shared fully in national productivity gains, they have not done so equally. The overwhelming evidence of a huge increase in income inequality in America has nothing to do with price indexes and is therefore unaffected by recent statistical revelations. It is still true that families in the bottom fifth, who had 5.4 percent of total income in 1970, had only 4.2 percent in 1994; and that over the same period the share of the top 5 percent went from 15.6 to 20.1. And it is still true that corporate C.E.O.'s, who used to make about 35 times as much as their employees, now make 120 times as much or more.... ...While these are real and serious problems, however, one thing is now clear: the truth about what is happening in America is more subtle than the simplistic morality play about greedy capitalists and oppressed workers that so many would- be sophisticates accepted only a few months ago. There was little excuse for buying into that simplistic view then; there is no excuse now.... It can be inferred from the passage that in the 1950s and 1960s:

  A. workers accounted for approximately the same percentage of national income as in 1994.
  B. workers experienced more substantial yearly pay increases than did workers in the 1970's and 1980's.
  C. workers' wages, according to a revised C.P.I., increased at a rate higher than economic progress.
  D. workers' incomes accurately reflected the period's economic progress.
  B. workers experienced more substantial yearly pay increases than did workers in the 1970's and 1980's.

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  Explanation/Reference:

  First, the passage implies that the 1950s and 1960s were decades of economic progress when the author states in paragraph five that "the rate of economic progress over the past 25 years has been much slower than it was in the previous 25." Paragraph five points out that percentage wise the median incomes of families increased by 35 percent in the last 25 years and 100 percent in the previous 25 years. This would indicate that the family workers in the 50s and 60s received more substantial yearly pay increases in the 50s and 60s than they did in the late 70s through the early 90s. Choice A is incorrect, as there is no specific indication in the passage that workers in the 50s and 60s amassed the same percentage of national income that workers did in 1994. The only information that the passage gives is that workers' wages in 1978 accounted for about the same share of national income as wages in 1994. Choice C is incorrect. There is no indication in the passage that the C.P.I. increased wages at a rate higher than economic progress in the 50s and 60s. Choice D is incorrect. On the contrary, we cannot be sure from the information in the passage that workers' incomes accurately reflected the significant economic progress of the period because the passage notes that over the years 1945 to 1970, the income of the median family rose 100 percent. The last line of paragraph five states that if we "Boskinized" data from the 50s and 60s we would see an undervalued rate of economic progress.

• Question 593:

  The Russian wheat aphid, Diuraphis noxia, is a small green insect discovered in southern Russia around the turn of the century. Agricultural researchers are not quite sure, but they believe the Russian aphid adapted itself to wheat about ten thousand years ago, when the crop was first domesticated by man. What is not in doubt is the insect's destructiveness. Spread by both wind and human transport, the Russian aphid has destroyed wheat fields throughout Asia, Africa, and Latin America. Until a few years ago, the United States had been free of this pest. But in the spring of 1986, a swarm of Russian aphids crossed the Mexican border and settled a few hundred miles north, in central Texas. From there, it quickly spread to other Western states, destroying wheat fields all along its path. In fact, the level of destruction has been so great over the past five years that entomologists are calling the Russian aphid the greatest threat to American agriculture since the Hessian fly, Phytophaga destructor, was inadvertently brought to the colonies on ships by German mercenary troops during the Revolutionary War. A combination of several factors have made it particularly difficult to deal with the threat posed by this aphid. First, Russian aphids reproduce asexually at a phenomenal rate. This process, known as parthenogenesis, often results in as many as twenty generations of insects in a single year. Although most generations remain in a limited geographic area because they have no wings, a few generations are born with wings, allowing the insect to spread to new areas. Second, because wheat is a crop with a very low profit margin, most American farmers do not spray it with pesticides; it simply is not economical to do so. And since the Russian aphid has only recently entered the United States, it has no natural enemies among North American insects or animals. As a result, there have been no man-made or natural obstacles to the spread of the Russian aphid in the United States. Agricultural researchers seeking to control the Russian aphid have looked to its place of origin for answers. In the Soviet Union, the Russian aphid has been kept in check by predators which have evolved alongside it over many thousands of years. One species of wasp seems to be particularly efficient at destroying the aphid. The pregnant females of the species search the Russian aphid's home, the interior of a wheat stalk, sting the aphid into paralysis, and then inject an egg into its body. When the egg hatches the wasp larva feeds off of the aphid, killing it in the process.

  The introduction of predators like the wasp, coupled with the breeding of new strains of insect-resistant wheat, may substantially curb the destructiveness of the Russian aphid in the future. For the time being, however, American farmers are left to their own devices when it comes to protecting their wheat crops

  The author suggests the best way to control the Russian aphid population in the United States is to:

  A. devote less acreage to the production of wheat.
  B. spray wheat fields with large quantities of pesticides.
  C. transplant its natural enemies from the Soviet Union.
  D. disrupt its reproductive process by sterilizing females.
  C. transplant its natural enemies from the Soviet Union.

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  Explanation/Reference:

  This is an inference question about the author's perspective on how to control the Russian aphid population in the United States. The last 2 paragraphs of the passage concern control of the aphid population. In the first sentence of the fifth paragraph, the author suggests that the introduction of the aphid's natural predators into the United States holds the possibility of controlling the aphid population in the future. In other words, the author thinks that transplanting the Russian aphid's natural enemies from the Soviet Union, choice (C), is a logical way of controlling the aphid population in the United States, so (C) is the correct answer to this question. Nowhere in the passage does the author state or suggest that reducing the acreage devoted to the production of wheat, choice (A), would control the aphid population in the United States, so (A) is wrong. Although some people might logically conclude that growing less wheat would lessen the aphid population in the long-run, but the author doesn't suggest this as a logical method of aphid control. The question stem asks for a suggestion of the author. As for spraying large quantities of pesticides on wheat fields, choice (B), the author indicates in the fifth sentence of the third paragraph that, for economic reasons, this is not a reasonable method of aphid control, so choice (B) is wrong. Finally, the author doesn't suggest that sterilizing female aphids is a logical way of controlling the aphid population in the United States, making choice (D) incorrect. In fact, in the first half of the third paragraph, the author makes a point of noting that aphids reproduce asexually at a phenomenal rate, so "sterilizing females" is not logical at all and certainly is not suggested by the author.

• Question 594:

  Today's new urban Asia is just as sophisticated and in many ways more exciting than Western cities. Urban Asian consumers are knowledgeable, modern, and keen to embrace the global lifestyle. Young, urban Asians have grown up accustomed to many things that originated in the West. They have, for example, completely embraced pizza, some even claiming that it is a part of their heritage. The story is told about a young Singaporean boy who was taken by his father to Rome. "Hey, look, Dad," the little boy exclaimed, "they have pizza here too!" On sampling the product, the boy decided that it was not as good as the original back home. Nury Vitachi, who writes for the South China Post and the Far Eastern Economic Review, describes the Asian middle-class phenomenon: "Executives in Asia have become rich at warp speed by taking full control of their own lives. They invest a great deal of time in their work, they use strategy to scramble up the corporate ladder, and they demand payment in cash -- so they can make their money work as hard as they do." Signs of affluence are everywhere, but don't get carried away. Traveling around Asia, no matter how rich the Asians become, signs of their frugal nature are still apparent. And they are very cost-conscious. Shopkeepers in many Asian cities, most notably in Hong Kong, demand payments for discounted merchandise in cash instead of plastic, and many Asians are accustomed to that. Most people save the increases in their income, and many prefer to put it into fixed or other income-generating assets. Stock, land, and property are their favorites. Many affluent Asians still regard financial security as the most important form of security, and they are confident that Asia is the place to be to achieve that. While many have begun to savor the good life, they are not letting go of their top priority of education for their children. Education is looked upon as the most important contributing factor to success in life. And in many of Asia's competitive urban centers, there is a rush to acquire a second degree and other forms of professional qualification to ensure personal competitiveness in the workplace. There are extraordinary opportunities in Asia for education and training programs from language to software programming. Despite the rise in their assertiveness, Asians still look to the United States and not so much to Europe for ideas and trends. In general, except for those in Hong Kong and Japan, they are not particularly concerned with being fashionable. For today's Asia, Japan and Hong Kong are the sources of Asian fashion ideas, but as Asia becomes more affluent, there is a great opportunity to develop an indigenous fashion industry. For example, a huge market potential exists in introducing new materials and simplified but fashionable designs for countries in tropical Asia with a hot humid climate throughout the year. The population density and lack of space in urban areas has prohibited Asians from exercising frequently and few indulge in outdoor activities. This is changing. Most Asians consider themselves in good health. Compared with Americans, few are overweight -- largely as a result of their Asian diet. But now health clubs are becoming popular among younger Asians. Potential for indoor exercise equipment holds great promise. It is also important to dress for the gym, and younger Asians are serious about looking good, complete with makeup, sunglasses, designer exercise shoes and outfits, and a gym bag. In trying to hit Asia's moving targets, regardless of what you are selling, it is a good idea to stick with market density -- not country by country, but, mostly, city by city. Asian markets can be a marketer's dream in that their densities are among the highest in the world. Java, Indonesia's main island, has 115 million people. On Nanjing Road, Shanghai's busiest street, businesses are open twelve hours a day almost every day of the year. More than 1.5 million people visit the shops there and spend more than $50 million every day. Someone said that you can only become rich if you sell to the rich. I would add that you can become rich faster if you sell to the new rich. For investors in the West, watch for Western companies that are preparing a big push in Asia. The world has not yet seen anything like it before, and you can reap handsome dividends if you back those stocks that are going eastward.

  According to the author, many Asians view education as:

  A. the most fulfilling aspect of life.
  B. a sector with tremendous growth opportunity.
  C. the foremost step toward personal success.
  D. an indicator of a family's wealth and breeding.
  C. the foremost step toward personal success.

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  Explanation/Reference:

  Substantiation for this can be found in the fourth paragraph. Education, it is said, is considered as the most important factor in success. Choice A is incorrect, since education is viewed as a means to financial security and success, rather than as something that is intrinsically valuable for its edifying capacity. The author seems to believe that choice B to be correct, as indicated in the last sentence of the fourth paragraph, but he does not represent that as a view held by Asians themselves. Choice D is incorrect since there is no mention of breeding in the passage and even though Asians tend to believe that education is important to success, there is no evidence that they see such a strong correlation between the two that it can serve as an indicator for wealth.

• Question 595:

  A continuous spectrum of light, sometimes called blackbody radiation, is emitted from a region of the Sun called the photosphere. Although the continuous spectrum contains light of all wavelengths, the intensity of the emitted light is much greater at some wavelengths than at others. The relationship between the most intense wavelength of blackbody radiation and the temperature of the emitting body is given by Wien's law, λ = 2.9 x 106 /T, where λ is the wavelength in nanometers and T is the temperature in kelvins.

  As the blackbody radiation from the Sun passes through the cooler gases in the Sun's atmosphere, some of the photons are absorbed by the atoms in these gases. A photon will be absorbed if it has just enough energy to excite an electron from a lower energy state to a higher one. The absorbed photon will have an energy equal to the energy difference between these two states. The energy of a photon is given by E = hf = hc/λ where h = 6.63 x 10-34 J•s, Planck's constant, and c = 3 x 108 m/s, the speed of light in a vacuum.

  The Sun is composed primarily of hydrogen. Electron transitions in the hydrogen atom from energy state n = 2 to higher energy states are listed below along with the energy of the absorbed photon:

  Final Energy State Energy (x 10-19 J)

  n = 3

  3.02

  n = 4

  4.08

  n = 5

  4.57 n = 6

  4.84 n = ∞

  5.44

  The energy absorbed by a hydrogen atom as its electron undergoes a transition from the n = 1 energy state to the n = ∞ state is: (Note: The n = 1 energy state is the ground state of hydrogen.)

  A. infinite.
  B. equal to the binding energy of the electron.
  C. equal to the energy of a zero-frequency photon.
  D. smaller than the energy absorbed in the n = 2 ton = transition.
  B. equal to the binding energy of the electron.

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  Explanation/Reference:

• Question 596:

  Which option is not an example of vertical social mobility?

  A. An individual loses his job and becomes homeless.
  B. An individual is promoted to a much more powerful position within the same company.
  C. An individual changes jobs and moves to a similar position at another company.
  D. All options are examples of vertical social mobility.
  C. An individual changes jobs and moves to a similar position at another company.

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  Explanation/Reference:

  Vertical social mobility involves a change in status. Moving to a similar position would not affect an individual's status.

• Question 597:

  Which of the following structures plays a role in both the male excretory and male reproductive systems, but in the female excretory system only?

  A. Epididymis
  B. Prostate
  C. Urethra
  D. Ureter
  C. Urethra

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  Explanation/Reference:

  This question tests your knowledge of the male and female reproductive and excretory systems, which, as you should know, are NOT identical in structure. The epididymis, choice A, is a group of coiled tubes sitting on top of the seminiferous tubules in the male reproductive tract. Sperm are produced in the seminiferous tubules and mature and acquire motility in the epididymis. Sperm are stored in the epididymis until ejaculation. Hence, the epididymis functions in the male reproductive system only; so choice A is wrong. Choice B, prostate, is one of the glands associated with the male reproductive tract; the prostate gland secretes and alkaline milky fluid that protects the sperm from the acidic conditions in the female reproductive tract. So, choice B also functions only in the male reproductive system, and is therefore incorrect. The urethra, choice C, is a structure found in both men and women. During ejaculation, sperm travels from the epididymis, through the vas deferens, and through the urethra, which opens to the outside from the tip of the penis. The urethra is also directly connected to the bladder. Hence, in males, the urethra functions in both the reproductive and excretory systems. In females, however, the reproductive and excretory systems do NOT share a common pathway. Sperm enter the vagina and travel up through the cervix, uterus, and fallopian tubes, and urine leaves the body through the urethra; the vagina and the urethra never meet -- they are SEPARATE openings. So, choice C is the right answer. Choice D, ureter, is the duct connecting the kidney to the bladder. Urine is formed in the kidneys, it travels down to the bladder by way of the ureters, and is stored there until it is excreted through the urethra. This process is the same in both sexes.

• Question 598:

  Breast milk is proven to be the best form of nutrition for infants and is recommended for at least 1 year after birth. Unfortunately, a recent survey of breastfeeding mothers revealed that only 20% continue breastfeeding or to provide breast milk through pumping after 4 months, after which they switch to formula. When asked about reasons for stopping breastfeeding, the top three reasons were: going back to work, lack of support, and difficulties pumping. A socioeconomic study of the mothers revealed that women who choose to breastfeed for longest tend to have a higher level of education and come from more affluent backgrounds. Conversely, those mothers who breastfeed for the least amount of time tend to belong to minority groups and are from poorer backgrounds. It has been proposed that cultural differences also have a significant impact on the duration of breastfeeding.

  According to the passage, if the Department of Health specifically wants to increase the minimum length of breastfeeding time, on whom should they focus their campaign?

  A. women from affluent backgrounds
  B. the whole population
  C. women from poor backgrounds
  D. minority groups
  D. minority groups

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  Explanation/Reference:

  The passage states that minority groups from poor backgrounds tend to breastfeed for the least amount of time and also highlights the importance of cultural differences. These factors imply that minority groups would need to be primarily considered when developing a campaign.

• Question 599:

  According to Piaget, which is the first stage of cognitive development?

  A. sensorimotor
  B. formal operational
  C. concrete operational
  D. preoperational
  A. sensorimotor

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  Explanation/Reference:

  This stage is a period of rapid cognitive growth which occurs from 0 to 2 years. The other options are later stages.

• Question 600:

  Saul Hoffman's scientific journal paper published in 2015 in Societies explores the relationship between two topics that at the surface are very distant from each other. As he goes on to state, "It is relatively easy, at least for an economist, to see why economists would be attracted to issues like teen pregnancy and teen childbearing, despite their apparent distance from the core topics of economics. First, economics ?especially microeconomics ?is fundamentally the study of choices that individuals make, traditionally and most often in formal markets with monetary prices, but now more and more frequently outside that sphere. Viewed from that perspective, choices involving sexual and fertility behavior among teens are an incredibly challenging, but inviting, target. Is it possible to identify the role of economic incentives, including government policy, on these behaviors? Is it sensible to apply traditional models of rational choice decision-making to teens?

  Second, the traditional concern about teen fertility was predicated on the notion that it was an economically catastrophic act. In a famous and oft-quoted 1968 article, Arthur Campbell wrote that 'The girl who has an illegitimate child at the age of 16 suddenly has 90 percent of her life's script written for her,' including reduced opportunities for schooling, the labor market, and marriage. But it doesn't take too much reflection to appreciate that more may be going on in leading to these poor outcomes than just a teen birth. Disentangling the causal effect of teen childbearing on subsequent socio-economic outcomes from its correlational effect is another deliciously inviting and challenging target, this time well-suited for the applied economist or econometrician.

  Just to make all this yet more inviting, the two research strands are closely related. Suppose it could be demonstrated that for some teens the socio-economic impact of a teen birth was negligible. For example, maybe future prospects for some teens were equally poor with or without a birth or perhaps government programs provided substantial benefits, so that the net impact on socio-economic well-being was consequently small or even positive. Then, it might well be 'rational' in an economic sense to have a teen birth in the first place, thereby linking the research on the causal impact of a teen birth with the research on the choice determinants of a teen birth. So what came to be known as the teen birth `causes' literature and the teen birth `consequences' literature were clearly interrelated.

  And then, to add yet another layer of challenge, the teen fertility rate in the U.S. has fallen at a rate that is totally unprecedented. Teen fertility was once widespread, with most of it occurring within early and sometimes not entirely voluntary marriage. In 1960, the teen fertility rate was approximately 90 births per 1000, which implied that more than 40% of women ever had a teen birth. When I published my first article on teen births 25 years ago, the teen fertility rate was 60 births per 1000, down one-third from 1960, but it had increased six years in a row in what turned out to be a deviation from the downward trend. Since then the rate has declined every single year, except for a short but puzzling uptick between 2005 and 2007. In 2014, the teen fertility rate was 24.2 births per 1000, the lowest teen fertility rate ever recorded in the U.S., though still shockingly high by European standards. Thus, the rate fell by more than 50% during my professional association with the topic and by 70% since 1960. Of course, at the same time teen marital births largely disappeared, falling from 85% of teen births to 12%.

  This adds yet another focus for economic research. Why did the rate fall? Did it have anything to do with changes in the costs of teen childbearing or changes in policy? Is it a good thing or not?

  In this article I try to make sense out of these various research strands by providing a personal narrative through the economics literature on teen childbearing, with a special emphasis on the three issues discussed above. My goal is to make the literature, including some reasonably technical content, accessible and valuable to a non-economist."

  Hoffman, S. (2015). Teen Childbearing and Economics: A Short History of a 25-Year Research Love Affair. Societies, 5(3), 646-663. doi:10.3390/soc5030646

  What is the most likely reason for the author's use of quotation marks around "rational" in paragraph 3?

  A. The author disagrees with the idea that teen birth is rational and wishes to distance himself from it.
  B. The author disagrees with the way the term "rational" is used to indicate that economists might perceive teen birth as financially beneficial.
  C. The possible benefits of a teen birth are so small that it is not necessarily meaningful to describe them as "rational."
  D. The choice of having a teen birth might not have been thought out methodically, but makes sense according to a monetary cost/benefit analysis.
  D. The choice of having a teen birth might not have been thought out methodically, but makes sense according to a monetary cost/benefit analysis.

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  Explanation/Reference:

  This Reasoning-Within-the-Text question asks you to make sense of a stylistic choice in the passage. The author writes that "maybe future prospects for some teens were equally poor with or without a birth or perhaps government programs provided substantial benefits, so that the net impact on socio-economic well-being was consequently small or even positive. Then, it might well be 'rational' in an economic sense to have a teen birth in the first place..." The author thus clarifies that he is using "rational" in a specialized sense. He is trying to express that having a child could be financially advantageous, while distancing this sense of "rationality" from a more commonsensical one. A ?incorrect. The author does not express a strong personal opinion on the matter as opposed to what this answer choice suggests. Rather, the author seems to agree that it is meaningful to analyze behavior in terms of how it affects financial prospects. In saying that the author wishes to distance himself from it, it implies more of a moral than an economic approach. B ?incorrect. The author actually agrees with the use of the term";rationa"; within the context of teen birth. C 璱ncorrect. The author does suggest the hypothetical benefits of a teen birth may be small, but the focus of his argument is on why giving birth may not be financially catastrophic ?not that the benefits are rational.