Medical Tests MCAT-TEST Online Practice Questions and Exam Preparation

Medical Tests MCAT-TEST Online Questions & Answers

• Question 51:

  A student conducts a chemical analysis of the components of a popular soft drink. The beverage label shows that the drink contains carbonated water, phosphoric acid, caffeine, and caramel color, but does not indicate the concentrations of these chemicals.

  

  Dissolved carbon dioxide will react reversibly with water to form carbonic acid. In an attempt to analyze the beverage composition, the student conducts the following experiments on a one liter sample of the beverage.

  Experiment 1

  The sample is placed in a sealed beaker cooled to 10?C and a vacuum is created in the space above the beverage. The gas pumped from this space is passed through a solution of BaCl2, producing a white precipitate. The process

  continues until no more precipitate forms. The precipitate is dried and found to have a mass of 9.5 grams.

  Experiment 2

  The remaining solution left in the sealed beaker is then titrated with 0.01 M NaOH to give the titration curve shown in Figure 1.

  

  Figure 1

  

  Why did the student choose to keep the sealed beaker of beverage at 10?C while vacuuming the from solution?

  

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

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  Explanation/Reference:

  The beverage is kept at a low temperature to reduce its kinetic energy and minimize the loss of water by evaporation. If too much water were lost, the concentration of the remaining fluid would increase and inaccurate measurements of the

  phosphoric acid concentration would result. Choice A is incorrect because CO2 is a non-polar molecule and would not be involved in dipole-dipole interactions with water.

  Choice B is incorrect because extracting the gas from the beverage would not result in a violent expansion of the gas.

  Choice D is incorrect because reducing the temperature would decrease the kinetic energy.

• Question 52:

  In the United States, breast cancer is the second leading cause of death for women, and as a result, the American Cancer Society, has recommended annual mammography screening for women age 40 years and older. It is estimated that the risk of mortality can be reduced through this procedure by approximately 20-25% during a ten-year period for women age 40 years and older.

  In general, cancer screening behaviors have increased in the United States. According to the National Health Interview Survey, in 1987, approximately 29% of women age 40 years and older reported having had a mammogram in the last 2 years. By 2000, this increased to 70%. However, there are racial disparities, as fewer African American and Hispanic women have mammograms compared to their Caucasian female counterparts. Some studies have looked into these differences. Cultural factors seem to play a role in minority women obtaining fewer mammograms. Asian women, for example, do not like to discuss sensitive topics with strangers.

  Prevention promotions have been designed to increase awareness for the need of breast cancer screening, particularly for women in racial and ethnic minority groups. An innovative breast cancer education program, called the Educational Intervention Asian Grocery Store-Based Education Program, was designed to target Asian women. Located in 20 different Asian grocery stores in communities, the cancer screening exhibits were placed at the entrances of the stores. As Asian women came into the grocery store, health information was passed out to Asian women. Even though only a small amount of women who were considered non-adherents to breast cancer screening ended up scheduling a screening, the study demonstrated an innovative culturally competent approach to health promotion.

  Source: Adapted from G.R. Sadler, P.R. Beerman, K. Lee et al. "Promoting Breast Cancer Screening Among Asian American Women: The Asian Grocery Store Based Cancer Education Program." Copyright 2012 Journal of Cancer Education.

  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 manipulation technique
  C. Fear then relief technique
  D. Lowball technique
  A. Social exchange technique

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  Explanation/Reference:

  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.

• Question 53:

  Due to ever-increasing paranoia about the transmission of hepatitis and AIDS via blood transfusions and the frequent difficulty of procuring matching blood donors for patients, researchers have been working at a feverish pace to produce disease-free and easy-to-use blood substitutes. The difficulty most synthetic blood researches have had is in formulating a substance that combines qualities of sterility, high capacity for carrying oxygen to body tissues, and versatility within the human body. Three major substitute technologies have been developed to date; each has certain advantages and shortcomings.

  "Red blood," the first of the blood substitute technologies, is derived from hemoglobin which has been recycled from old, dead, or worn-out red blood cells and modified so that it can carry oxygen outside the red blood cell. Hemoglobin, a complex protein, is the blood's natural oxygen carrier and is attractive to scientists for use in synthetic blood because of its oxygen-carrying capacity. However, hemoglobin can sometimes constitute a two-fold threat to humans when it is extracted from the red blood cell and introduced to the body in its naked form. First, hemoglobin molecules are rarely sterile and often remain contaminated by viruses to which they were exposed in the cell. Second, naked hemoglobin is extremely dangerous to the kidneys, causing blood flow at these organs to shut down and leading, ultimately, to renal failure. Additional problems arise from the fact that hemoglobin is adapted to operate optimally within the intricate environment of the red blood cell. Stripped of the protection of the cell, the hemoglobin molecule tends to suffer breakdown within several hours. Although modification has produced more durable hemoglobin molecules which do not cause renal failure, undesired side effects continue to plague patients and hinder the development of hemoglobin-based blood substitutes.

  Another synthetic blood alternative, "white blood", is dependent on laboratory synthesized chemicals called perfluorocarbons (PFCs). Unlike blood, PFCs are clear oil like liquids, yet they are capable of absorbing quantities of oxygen up to 50% of their volume, enough of an oxygen carrying potential for oxygen-dependent organisms to survive submerged in the liquid for hours by "breathing" it. Although PFCs imitate real blood by effectively absorbing oxygen, scientists are primarily interested in them as constituents of blood substitutes because they are inherently safer to use than hemoglobin-based substitutes. PFCs do not interact with any chemicals in the body and can be manufactured in near-perfect sterility. The primary pitfall of PFCs is in their tendency to form globules in plasma that can block circulation. Dissolving PFCs in solution can mitigate globulation; however, this procedure also seriously curtails the PFCs' oxygen capacity.

  The final and perhaps most ambitious attempt to form a blood substitute involves the synthesis of a modified version of human hemoglobin by genetically-altered bacteria. Fortunately, this synthetic hemoglobin seems to closely mimic the qualities of sterility, and durability outside the cellular environment, and the oxygen-carrying efficiency of blood. Furthermore, researchers have found that if modified hemoglobin genes are added to bacterial DNA, the bacteria will produce the desired product in copious quantities. This procedure is extremely challenging, however, because it requires the isolation of the human gene for the production of hemoglobin, and the modification of the gene to express a molecule that works without support from a living cell.

  While all the above technologies have serious drawbacks and difficulties, work to perfect an ideal blood substitute continues. Scientists hope that in the near future safe synthetic blood transfusions may ease blood shortages and resolve the unavailability of various blood types.

  It can be inferred from the passage that the difficulty of producing an ideal blood substitute is compounded by all of the following EXCEPT:

  A. there is no known way to isolate the DNA responsible for hemoglobin.
  B. naked hemoglobin tends to break down in the bloodstream.
  C. non-globulating PFCs have significantly abbreviated oxygen-carrying capacities.
  D. the use of PFCs may lead to blood clotting.
  A. there is no known way to isolate the DNA responsible for hemoglobin.

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  Explanation/Reference:

  This is an inference question. It asks which of the answer choices is not a factor that detracts from the production of an ideal blood substitute. Choices (C) and (D) present troublesome aspects of PFCs. The end of the second paragraph establishes that one of the drawbacks of PFCs is that they form globules, blocking blood circulation, choice (D). In order to bypass this problem, scientists have attempted to modify PFCs so that they do not form globules. These efforts have been thwarted, however, as such modified PFCs have curtailed oxygen-carrying capacities, choice (C). Choice (B) relates to problems with "red blood". The third sentence of the second paragraph tells us that one of the problems of "red blood" is that its naked hemoglobin breaks down rapidly in the bloodstream. Choice (B), then, is a factor that has compounded the difficulty of producing an ideal blood substitute. Choice (A) presents a statement which, if supported by the passage, might very well compound the difficulties of producing an ideal synthetic blood. If there was no known way to isolate the DNA responsible for hemoglobin, then genetic engineering of modified hemoglobin, would be hampered. But the passage never states that there is no known way to isolate the DNA responsible for hemoglobin. It does mention, in the last sentence of the fourth paragraph, that genetic engineering is challenging because it requires the isolation of the human gene for the production of hemoglobin. But the passage does not say that there is no known way to do this. Choice (A), therefore, is not suggested as a complication in the production of synthetic blood and is the correct answer.

• Question 54:

  Band theory explains the conductivity of certain solids by stating that the atomic orbitals of the individual atoms in the solid merge to produce a series of atomic orbitals comprising the entire solid. The closely-spaced energy levels of the orbitals form bands. The band corresponding to the outermost occupied subshell of the original atoms is called the valence band. If partially full, as in metals, it serves as a conduction band through which electrons can move freely. If the valence band is full, then electrons must be raised to a higher band for conduction to occur. The greater the band gap between the separate valence and conduction bands, the poorer the material's conductivity. Figure 1 shows the valence and conduction bands of a semiconductor, which is intermediate in conductivity between conductors and insulators.

  

  Figure 1

  When silicon, a semiconductor with tetrahedral covalent bonds, is heated, a few electrons escape into the conduction band. Doping the silicon with a few phosphorus atoms provides unbonded electrons that escape more easily, increasing conductivity. Doping with boron produces holes in the bonding structure, which may be filled by movement of nearby electrons within the lattice. When a semiconductor in an electric circuit has excess electrons on one side and holes on the other, electron flow occurs more easily from the side with excess electrons to the side with holes than in the reverse direction.

  

  Figure 2

  Why do phosphorus and boron atoms enhance the conductivity of silicon?

  A. Their electronegativities differ from that of silicon.
  B. They have different numbers of valence electrons.
  C. Their semimetallic nature makes them good semiconductors.
  D. They are better conductors than silicon even as pure substances.
  B. They have different numbers of valence electrons.

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  Explanation/Reference:

  The passage states that phosphorus atoms increase the conductivity of silicon because phosphorus provides the crystal with unbonded electrons, while boron atoms produce holes in the bonding structure. From the periodic table, it can be seen that boron has three valence electrons, silicon has four, and phosphorus has 5. Since the bonds in the silicon crystal are tetrahedral, a phosphorus atom surrounded by silicon atoms will be able to form covalent bonds with only four of its valence electrons, leaving the fifth one unbonded. Boron has only three valence electrons, so a boron atom surrounded by silicon atoms will only be able to form three covalent bonds, leaving a hole in the bonding structure of silicon. It is the presence of these unbonded electrons and holes that enhances the conductivity of phosphorus. Choice B is therefore the correct answer. Choice A is wrong because the difference in electronegativity between boron, phosphorus, and silicon is quite small. Choice C is wrong for two reasons: phosphorus isn't a semimetal and even if these two elements were both semimetals and good semiconductors, this in itself wouldn't explain the enhancement of silicon's conductivity produced by doping silicon with some of these elements. Choice D is wrong because, like choice C, it wouldn't explain the phenomenon the question asks about even if it were true.

• Question 55:

  Although nihilism is commonly defined as a form of extremist political thought, the term has a broader meaning. Nihilism is in fact a complex intellectual stance with venerable roots in the history of ideas, which forms the theoretical basis for many positive assertions of modern thought. Its essence is the systematic negation of all perceptual orders and assumptions. A complete view must account for the influence of two historical crosscurrents: philosophical skepticism about the ultimacy of any truth, and the mystical quest for that same pure truth. These are united by their categorical rejection of the "known." The outstanding representative of the former current, David Hume (1711?776), maintained that external reality is unknowable, since sense impressions are actually part of the contents of the mind. Their presumed correspondence to external "things" cannot be verified, since it can be checked only by other sense impressions. Hume further asserts that all abstract conceptions turn out, on examination, to be generalizations from sense impressions. He concludes that even such an apparently objective phenomenon as a cause-and-effect relationship between events may be no more than a subjective fabrication of the observer. Stanley Rosen notes: "Hume terminates in skepticism because he finds nothing within the subject but individual impressions and ideas." For mystics of every faith, the "experience of nothingness" is the goal of spiritual practice. Buddhist meditation techniques involve the systematic negation of all spiritual and intellectual constructs to make way for the apprehension of pure truth. St. John of the Cross similarly rejected every physical and mental symbolization of God as illusory. St. John's spiritual legacy is, as Michael Novak puts it, "the constant return to inner solitude, an unbroken awareness of the emptiness at the heart of consciousness. It is a harsh refusal to allow idols to be placed in the sanctuary. It requires also a scorching gaze upon all the bureaucracies, institutions, manipulators, and hucksters who employ technology and its supposed realities to bewitch and bedazzle the psyche." Novak's interpretation points to the way these philosophical and mystical traditions prepared the ground for the political nihilism of the nineteenth and twentieth centuries. The rejection of existing social institutions and their claims to authority is in the most basic sense made possible by Humean skepticism. The political nihilism of the Russian intelligentsia combined this radical skepticism with a near mystical faith in the power of a new beginning. Hence, their desire to destroy becomes a revolutionary affirmation; in the words of Stanley Rosen, "Nihilism is an attempt to overcome or repudiate the past on behalf of an unknown and unknowable, yet hoped-for, future". This fusion of skepticism and mystical re-creation can be traced in contemporary thought, for example as an element in the counterculture of the 1960s.

  The author's working definition of "nihilism", as it functions in the passage, is:

  A. systematic doubt of that which one takes for granted.
  B. a mystical quest for nothingness.
  C. a form of extremist political thought.
  D. rejection of all presently established institutions.
  A. systematic doubt of that which one takes for granted.

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  Explanation/Reference:

  This question asks you for the author's working definition of "nihilism". Remember that the author's definition is not necessarily the same as the usual definition of nihilism, a form of extremist political thought, so C is not correct. The definition that reflects the author's own thinking is provided in the second and third sentences of Paragraph 1. The author says there that nihilism is a complex intellectual stance whose essence is systematic negation of perceptual orders and assumptions. This points to Choice A as the correct answer.

  Choice B defines the essence of mysticism, not nihilism. Choice D is too narrow, being an aspect of political nihilism derived purely from skepticism.

• Question 56:

  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

  The author would likely view the choice of whether to use birth control as:

  A. a personal choice that should be governed by one's beliefs about the morality of using it.
  B. a decision governed by cost-benefit analyses including factors such as cost of the birth control.
  C. a sign of innate intelligence.
  D. an ethical choice involving having children only when one can provide them with a good life.
  B. a decision governed by cost-benefit analyses including factors such as cost of the birth control.

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  Explanation/Reference:

  This Reasoning-Beyond-the-Text question asks you to make inferences about the author's overall style of thought and how it might apply to a new topic. He describes economics as "fundamentally the study of choices that individuals make," with a focus on incentives, especially financial ones. A focus on incentives that prompt the choice to use birth control, and the factors that prevent them, could interest an economist. A ?incorrect. The author never describes behavior as moral or immoral, suggesting this is irrelevant to his explanatory framework in the passage. C ?incorrect. The passage does not discuss innate qualities of a person, but focuses on the outward forces that shape their choices. D ?incorrect. As with A, this choice focuses on ethics, while the passage discusses choices in an amoral way, as based on incentives.

• Question 57:

  Early experimentation on the single-celled organism Acetabularia led to important discoveries about the role of the nucleus in regulating cell function. Acetabularia is an enormous single cell with three distinct regions: a cap, a root-like rhizoid, and a stalk which connects the two. The following experiments were conducted to study the development of the cell:

  Experiment 1

  The stalk of an Acetabularia was cut, fragmenting the cell. The fragment which included the cap died shortly afterwards while the fragment containing the rhizoid regenerated to form a complete Acetabularia.

  Experiment 2

  The nucleus from Acetabularia mediterranea, which has a flat cap, was transplanted into Acetabularia crenulata, which has a tufted cap, following removal of the Acetabularia crenulata nucleus. The Acetabularia crenulata cap eventually assumed the flat shape.

  Experiment 3

  The nucleus of Acetabularia mediterranea was removed from the young cell before it first formed a cap. A normal cap formed several weeks later. The cell proved to be inviable and died shortly thereafter.

  Experiment 4

  A young Acetabularia was fractioned into a number of portions before it first formed a cap. Several weeks later, both the portion containing the nucleus and the portion containing the apical tip of the stalk formed caps. The other portions did not form caps.

  Acetabularia is a(n):

  A. virus.
  B. prokaryote.
  C. eukaryote.
  D. bacterium.
  C. eukaryote.

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  Explanation/Reference:

  The passage describes Acetabularia as a single cell with a nucleus. Only eukaryotes have nuclei, and other membrane bound organelles.

  Choice A is incorrect because a virus does not have a cell membrane, nucleus, or many of the other components of a cell. A virus is essentially composed of DNA or RNA and a protein coat.

  Choice B is incorrect because prokaryotes lack a nucleus.

  Choice D is incorrect because the term bacteria refers to prokaryotes which, by definition, lack nuclei.

• Question 58:

  For the last two decades many earth scientists have supported the notion that the Mediterranean was once a huge, dry desert, lying 3,000 meters below sea level. This "death valley" was thought to have existed at the end of Miocene time, about 6 to 5.5 million years ago.... ...From a geological point of view, the Mediterranean is a tectonically mobile land-enclosed depression -- small (about 3,000,000 square kilometers) in comparison to the major world oceans...Immediately obvious on all charts is the highly variable topography and relief of both the seafloor and adjacent borderland. The coastline is highly irregular and continental shelves, though generally narrow, are well developed off the major river deltas (Nile, Rhone, Po, and Ebro). Moreover, the deep-sea basins and trenches have distinctive relief, with basin plains ranging in depth from less than 1,000 meters to more than 4,000...Observation that rocks dredged offshore are similar to those on land raised a fundamental concept -- the key to understanding Mediterranean history lies in the adjacent emerged land masses, and vice- versa.... ...Early paleographic reconstructions showed that the once-open communication with the Atlantic deteriorated during the upper Miocene. Water-mass exchange continued for a while in the Rif Strait, but then ceased completely prior to the beginning of the Pliocene.... ...High relief near what is now the Strait of Gibraltar served as a barrier to the exchange of waters with the Atlantic. Exposed to a hot and dry climate, water evaporated and the then-dry basin elicited comparison with a gigantic Death Valley... Microfossil studies suggested that the depth of the Mediterranean basin at these times had been "deep." Estimates suggested a dry seafloor as far as 2,000 meters below ocean level... As a response to suddenly lowered sea level, rivers feeding the Mediterranean and canyons on the now-dry seafloor began a geologically dramatic phase of erosion. Deep, Grand Canyon-like gorges of the Nile and Rhone rivers, presently buried on land, were apparently cut during a great drawdown of water -- when the Mediterranean floor lay exposed 1,000 meters or more below its present level...The sudden flooding through a gigantic waterfall at Gibraltar drowned the exposed basin floor. These falls would have been 1,000 times bigger than Niagara Falls...This flooding event is recorded by the Miocene Pliocene boundary, a time when open marine faunal assemblages were suddenly reintroduced from the Atlantic.... ...Geological theories usually fall at a glacial pace into a sea of controversy, and this one is no exception. Today -- charging that proof for the theory is lacking -- many scientists believe that the Med always contained saltwater, with only the depth of the seafloor and the water being in question... Some of the tenets on which the theory was formulated are, if not defective, very seriously in question. To interpret their findings, a respectable number of geologists studying the surrounding emerged borderland as well as subsea sections indicate that alternative, more comprehensive concepts must be envisioned.... ...It is not realistic to envision the Mediterranean seafloor of about 5 million years ago as a desert at 3,000 meters below present ocean level. Several years ago...the Mediterranean [was compared] to a complex picture- puzzle that comprises numerous intricate pieces, many of which are already in place. A general image is emerging, although gaps in some areas of the picture remain fuzzy and indistinct.

  All of the following are characteristics of the modern day Mediterranean EXCEPT that it:

  A. has a variety of depths.
  B. has a seafloor with a very regular and smooth topography.
  C. is land-enclosed and tectonically mobile.
  D. contains well-developed continental shelves.
  B. has a seafloor with a very regular and smooth topography.

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  Explanation/Reference:

  Paragraph 2 provides all of the information required to answer this question. It states that the seafloor and adjacent borderland have highly variable topography and relief. So choice B is not a characteristic of the modern Mediterranean. The other choices can all be found in the description of the modern Mediterranean in paragraph 2.

• Question 59:

  The enzymes in pancreatic juice digest:

  A. carbohydrates and proteins only.
  B. carbohydrates and proteins only.
  C. fats and proteins only.
  D. carbohydrates, proteins and fats.
  D. carbohydrates, proteins and fats.

• Question 60:

  A hydropathy plot indicates the hydrophilicity (negative values) and hydrophobicity (positive values) of different regions of a protein. According to the hydropathy plot below, how many cellular membrane spanning regions are possible in this protein?

  

  A. 1
  B. 2
  C. 3
  D. 4
  B. 2

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  Explanation/Reference:

  The hydropathy plot indicates two regions of hydrophobicity. Because the cell membrane has a hydrophobic internal structure, hydrophobic regions of proteins can reside within the membrane.