Human anatomy is the scientific study of the body’s structures. Some of these structures are very small and can only be observed and analyzed with the assistance of a microscope. Other larger structures can readily be seen, manipulated, measured, and weighed. The word “anatomy” comes from a Greek root that means “to cut apart.” Human anatomy was first studied by observing the exterior of the body and observing the wounds of soldiers and other injuries. Later, physicians were allowed to dissect bodies of the dead to augment their knowledge. When a body is dissected, its structures are cut apart in order to observe their physical attributes and their relationships to one another. Dissection is still used in medical schools, anatomy courses, and in pathology labs.
The word augment is closest in meaning to:
(Increase) is correct because increase is closest in meaning to augment.
Types of Pressure
Pressure is a force exerted by a substance that is in contact with another substance. Atmospheric pressure is pressure exerted by the mixture of gases (primarily nitrogen and oxygen) in the Earth’s atmosphere. Although you may not perceive it, atmospheric pressure is constantly pressing down on your body. This pressure keeps gases within your body, such as the gaseous nitrogen in body fluids, dissolved. If you were suddenly ejected from a spaceship above Earth’s atmosphere, you would go from a situation of normal pressure to one of very low pressure. The pressure of the nitrogen gas in your blood would be much higher than the pressure of nitrogen in the space surrounding your body. As a result, the nitrogen gas in your blood would expand, forming bubbles that could block blood vessels and even cause cells to break apart.
Atmospheric pressure does more than just keep blood gases dissolved. Your ability to breathe—that is, to take in oxygen and release carbon dioxide—also depends upon a precise atmospheric pressure. Altitude sickness occurs in part because the atmosphere at high altitudes exerts less pressure, reducing the exchange of these gases, and causing shortness of breath, confusion, headache, lethargy, and nausea. Mountain climbers carry oxygen to reduce the effects of both low oxygen levels and low barometric pressure at higher altitudes.
Q. The word perceive in paragraph 1 is closest in meaning to:
(Realize) is correct because realize is closest in meaning to perceive in this situation.
Tissue and Aging
According to poet Ralph Waldo Emerson, “The surest poison is time.” In fact, biology confirms that many functions of the body decline with age. All the cells, tissues, and organs are affected by senescence (the process of deterioration) with noticeable variability between individuals owing to different genetic makeup and lifestyles. The outward signs of aging are easily recognizable. The skin and other tissues become thinner and drier, reducing their elasticity, contributing to wrinkles and high blood pressure. Hair turns gray because follicles produce less melanin, the brown pigment of hair and the iris of the eye. The face looks flabby because elastic and collagen fibers decrease in connective tissue and muscle tone is lost. Glasses and hearing aids may become parts of life as the senses slowly deteriorate, all due to reduced elasticity. Overall height decreases as the bones lose calcium and other minerals. With age, fluid decreases in the fibrous cartilage disks intercalated between the vertebrate in the spine. Joints lose cartilage and stiffen. Many tissues, including those in muscles, lose mass through a process called atrophy. Lumps and rigidity become more widespread. As a consequence, the passageways, blood vessels, and airways become more rigid. The brain and spinal cord lose mass. Nerves do not transmit impulses with the same speed and frequency as in the past. Some loss of thought clarity and memory can accompany aging. More severe problems are not necessarily associated with the aging process and may be symptoms of underlying illness. As exterior signs of aging increase, so do the interior signs, which are not as noticeable.
Q. The word variability is closest in meaning to:
Difference is correct because difference is closest in meaning to variability in this case. Although indifference looks similar to difference, it is not related.
One of the most talked about diseases is skin cancer. Cancer is a broad term that describes diseases caused by abnormal cells in the body dividing uncontrollably. Most cancers are identified by the organ or tissue in which the cancer originates. One common form of cancer is skin cancer. The Skin Cancer Foundation reports that one in five Americans will experience some type of skin cancer in their lifetime. The degradation of the ozone layer in the atmosphere and the resulting increase in exposure to UV radiation has contributed to its rise. Overexposure to UV radiation damages DNA, which can lead to the formation of cancerous lesions. Although melanin offers some protection against DNA damage from the sun, often it is not enough. The fact that cancers can also occur on areas of the body that are normally not exposed to UV radiation suggests that there are additional factors that can lead to cancerous lesions.
Q. The word degradation is closest in meaning to:
Deterioration is correct because deterioration is closest in meaning to degradation as both refer to a process in which something gets progressively worse or less.
Fixed and Wandering Stars
Ancient Babylonian, Assyrian, and Egyptian astronomers knew the approximate length of the year. The Egyptians of 3000 years ago, for example, adopted a calendar based on a 365-day year. They kept careful track of the rising time of the bright star Sirius in the predawn sky, which has a yearly cycle that corresponded with the flooding of the Nile River. The Chinese also had a working calendar; they determined the length of the year at about the same time as the Egyptians. The Chinese also recorded comets, bright meteors, and dark spots on the Sun. Later, Chinese astronomers kept careful records of “guest stars”—those that are normally too faint to see but suddenly flare up to become visible to the unaided eye for a few weeks or months. We still use some of these records in studying stars that exploded a long time ago.
Q. The phrase corresponded with is closest in meaning to
Aligned with is correct because correspond with, in this situation, refers to two events that happen at the same time – they are aligned with each other.
The Nature Of Astronomy
Astronomy is defined as the study of the objects that lie beyond our planet Earth and the processes by which these objects interact with one another. We will see, though, that it is much more. It is also humanity’s attempt to organize what we learn into a clear history of the universe, from the instant of its birth in the Big Bang to the present Moment.
In considering the history of the universe, we will see again and again that the cosmos evolves; it changes in profound ways over long periods of time. For example, the universe made the carbon, the calcium, and the oxygen necessary to construct something as interesting and complicated as you. Today, many billions of years later, the universe has evolved into a more hospitable place for life. Tracing the evolutionary processes that continue to shape the universe is one of the most important (and satisfying) parts of modern astronomy.
Q. Why does the author say “For example, the universe made the carbon, the calcium, and the oxygen necessary to construct something as interesting and complicated as you”?
A is the correct answer because the specific example is directly preceded by a broad statement about how the “universe changes in profound ways over long periods of time”. It does not explain why the universe changes over time (B), nor does it describe a field of study (C) or how the universe evolves quickly (D).
Europa, a Moon with an Ocean
Europa and the inner two Galilean moons, are not icy worlds like most of the moons of the outer planets. With densities and sizes similar to our Moon, they appear to be predominantly rocky objects.
The most probable cause is Jupiter itself, which was hot enough to radiate a great deal of infrared energy during the first few million years after its formation. This infrared radiation would have heated the disk of material near the planet that would eventually coalesce into the closer moons.
Thus, any ice near Jupiter was vaporized, leaving Europa with compositions similar to planets in the inner solar system.
Despite its mainly rocky composition, Europa has an ice-covered surface, as astronomers have long known from examining spectra of sunlight reflected from it. In this it resembles Earth, which has a layer of water on its surface, but in Europa’s case the water is capped by a thick crust of ice. There are very few impact craters in this ice, indicating that the surface of Europa is in a continual state of geological self-renewal. Judging from crater counts, the surface must be no more than a few million years old, and perhaps substantially less. In terms of its ability to erase impact craters, Europa is more geologically active than Earth.
When we look at close-up photos of Europa, we see a strange, complicated surface. For the most part, the icy crust is extremely smooth, but it is crisscrossed with cracks and low ridges that often stretch for thousands of kilometers. Some of these long lines are single, but most are double or multiple, looking rather like the remnants of a colossal freeway system.
Q. In paragraph 5, the author mentions “close-up photos of Europa” in order to:
D is correct because features of the surface of Europa are described immediately following this. Since the passage is about the surface and appearance of Europa, the author concludes the passage with a summary of the observations based on the photos s/he mentions. C is also incorrect because Europa is a moon, not a planet.
The Invention of the X-Ray
German physicist Wilhelm Röntgen (1845–1923) was experimenting with electrical current when he discovered that a mysterious and invisible “ray” would pass through his flesh but leave an outline of his bones on a screen coated with a metal compound. In 1895, Röntgen made the first durable record of the internal parts of a living human: an “X-ray” image (as it came to be called) of his wife’s hand. Scientists around the world quickly began their own experiments with X-rays, and by 1900, X-rays were widely used to detect a variety of injuries and diseases. In 1901, Röntgen was awarded the first Nobel Prize for physics for his work in this field. The X-ray is a form of high energy electromagnetic radiation with a short wavelength capable of penetrating solids and ionizing gases. As they are used in medicine, X-rays are emitted from an X-ray machine and directed toward a specially treated metallic plate placed behind the patient’s body. The beam of radiation results in darkening of the X-ray plate. X-rays are slightly impeded by soft tissues, which show up as gray on the X-ray plate, whereas hard tissues, such as bone, largely block the rays, producing a light- toned “shadow.” Thus, X-rays are best used to visualize hard body structures such as teeth and bones. Like many forms of high energy radiation, however, X-rays are capable of damaging cells and initiating changes that can lead to cancer. This danger of excessive exposure to X-rays was not fully appreciated for many years after their widespread use.
Q. Why does the author say “mysterious and invisible “ray”?
B is correct because the technology was not fully understood at the time, which is stated earlier in the passage. The science behind it was unknown and, thus, the author refers to it as “mysterious”.
The Internal Compartments of the Human Body
A human body consists of trillions of cells organized in a way that maintains distinct internal compartments. These compartments keep body cells separated from external environmental threats and keep the cells moist and nourished. They also separate internal body fluids from the countless microorganisms that grow on body surfaces, including the lining of certain tracts, or passageways. The intestinal tract, for example, is home to even more bacteria cells than the total of all human cells in the body, yet these bacteria are outside the body and cannot be allowed to circulate freely inside the body. Cells, for example, have a cell membrane (also referred to as the plasma membrane) that keeps the intracellular environment—the fluids and organelles—separate from the extracellular environment. Blood vessels keep blood inside a closed circulatory system, and nerves and muscles are wrapped in connective tissue sheaths that separate them from surrounding structures. In the chest and abdomen, a variety of internal membranes keep major organs such as the lungs, heart, and kidneys separate from others.
Q. Why does the author say “yet these bacteria are outside the body and cannot be allowed to circulate freely inside the body”?
C is the correct answer. Option A is incorrect as it was was mentioned previously in the passage. The statement does not explain why bacteria are not allowed to circulate inside the body (B). Finally, the statement does not show contrast between types of compartments, so D is incorrect.
The Sapir-Whorf Hypothesis
The Sapir-Whorf hypothesis is based on the idea that people experience their world through their language, and that they therefore understand their world through the culture embedded in their language. The hypothesis, which has also been called linguistic relativity, states that language shapes thought. Studies have shown, for instance, that unless people have access to the word “ambivalent,” they don’t recognize an experience of uncertainty due to conflicting positive and negative feelings about one issue. Essentially, the hypothesis argues, if a person can’t describe the experience, the person is not having the experience.
Q. Why does the author say “the hypothesis argues”?
C is correct because the author uses this short phrase, “the hypothesis argues”, to emphasize that this hypothesis – also called linguistic relativity – is just a claim, not necessarily proven or agreed upon.
The Terrestrial Planets
The terrestrial planets are quite different from the giants. In addition to being much smaller, they are composed primarily of rocks and metals. These, in turn, are made of elements that are less common in the universe as a whole. The most abundant rocks, called silicates, are made of silicon and oxygen, and the most common metal is iron. We can tell from their densities that Mercury has the greatest proportion of metals (which are denser) and the Moon has the lowest. Earth, Venus, and Mars all have roughly similar bulk compositions: about one third of their mass consists of iron-nickel or iron-sulfur combinations; two thirds is made of silicates. Because these planets are largely composed of oxygen compounds (such as the silicate minerals of their crusts), their chemistry is said to be oxidized.
When we look at the internal structure of each of the terrestrial planets, we find that the densest metals are in a central core, with the lighter silicates near the surface. If these planets were liquid, like the giant planets, we could understand this effect as the result the sinking of heavier elements due to the pull of gravity. This leads us to conclude that, although the terrestrial planets are solid today, at one time they must have been hot enough to melt.
Differentiation is the process by which gravity helps separate a planet’s interior into layers of different compositions and densities. The heavier metals sink to form a core, while the lightest minerals float to the surface to form a crust. Later, when the planet cools, this layered structure is preserved. In order for a rocky planet to differentiate, it must be heated to the melting point of rocks, which is typically more than 1,800 F.
Q. Which of the following can be inferred about the past temperatures of terrestrial planets?
A is correct because paragraph 2 says that the planets “must have been hot enough to melt” while paragraph 3 states that the melting point is usually more than 1,800 F. This question is challenging since the information to find the correct answer is spread across two paragraphs.
Geology is the study of Earth’s crust and the processes that have shaped its surface throughout history. Heat escaping from the interior provides energy for the formation of our planet’s mountains, valleys, volcanoes, and even the continents and ocean basins themselves. But not until the middle of the twentieth century did geologists succeed in understanding just how these landforms are created.
Plate tectonics is a theory that explains how slow motions within the mantle of Earth move large segments of the crust, resulting in a gradual “drifting” of the continents as well as the formation of mountains and other large-scale geological features. Plate tectonics is a concept as basic to geology as evolution by natural selection is to biology or gravity is to understanding the orbits of planets. Looking at it from a different perspective, plate tectonics is a mechanism for Earth to transport heat efficiently from the interior, where it has accumulated, out to space. It is a cooling system for the planet. All planets develop a heat transfer process as they evolve; mechanisms may differ from that on Earth as a result of chemical makeup and other constraints.
Q. What can be inferred from paragraph 2 about the state of the Earth without plate tectonics?
C is correct because paragraph 2 mentions that plate tectonics are a “cooling system” for Earth to release heat from its interior.
Because the wavelengths of X-rays (10-10,000 picometers [pm]) are comparable to the size of atoms, X-rays can be used to determine the structure of molecules. When a beam of X-rays is passed through molecules packed together in a crystal, the X-rays collide with the electrons and scatter. Constructive and destructive interference of these scattered X-rays creates a specific diffraction pattern. Calculating backward from this pattern, the positions of each of the atoms in the molecule can be determined very precisely. One of the pioneers who helped create this technology was Dorothy Crowfoot Hodgkin.
She was born in Cairo, Egypt, in 1910, where her British parents were studying archeology. Even as a young girl, she was fascinated with minerals and crystals. When she was a student at Oxford University, she began researching how X-ray crystallography could be used to determine the structure of biomolecules. She invented new techniques that allowed her and her students to determine the structures of vitamin B12, penicillin, and many other important molecules. Diabetes, a disease that affects 382 million people worldwide, involves the hormone insulin. Hodgkin began studying the structure of insulin in 1934, but it required several decades of advances in the field before she finally reported the structure in 1969. Understanding the structure has led to better understanding of the disease and treatment options.
Q. What can be inferred about Dorothy Hodgkin and her discovery of this technology?
D is correct because Dorothy Hodgkin determined the structures of certain vitamins and medicines (penicillin) and other helpful substances (insulin) that allowed other scientists to better understand and utilize them in treating sufferers.
During long space missions, astronauts can lose approximately 1 to 2 percent of their bone mass per month. This loss of bone mass is thought to be caused by the lack of mechanical stress on astronauts’ bones due to the low gravitational forces in space. Lack of mechanical stress causes bones to lose mineral salts and collagen fibers, and thus strength. Similarly, mechanical stress stimulates the deposition of mineral salts and collagen fibers. The internal and external structure of a bone will change as stress increases or decreases so that the bone is an ideal size and weight for the amount of activity it endures. That is why people who exercise regularly have thicker bones than people who are more sedentary. It is also why a broken bone in a cast atrophies while its contralateral mate maintains its concentration of mineral salts and collagen fibers. The bones undergo remodeling as a result of forces (or lack of forces) placed on them.
Q. Which of the following can be inferred from this passage?
A is correct because the passage states that more active people have thicker bones because mechanical stress deposits mineral salts and collagen fibers, which create more bone strength and density. Therefore, those who are less active have thinner, weaker bones.
The common name for a disruption of blood supply to the brain is a stroke. It is caused by a blockage to an artery in the brain. The blockage is from some type of embolus: a blood clot, a fat embolus, or an air bubble. When the blood cannot travel through the artery, the surrounding tissue that is deprived starves and dies. Strokes will often result in the loss of very specific functions. A stroke in the lateral medulla, for example, can cause a loss in the ability to swallow. Sometimes, seemingly unrelated functions will be lost because they are dependent on structures in the same region. Along with the swallowing in the previous example, a stroke in that region could affect sensory functions from the face or extremities because important white matter pathways also pass through the lateral medulla. Loss of blood flow to specific regions of the cortex can lead to the loss of specific higher functions, from the ability to recognize faces to the ability to move a particular region of the body. Severe or limited memory loss can be the result of a temporal lobe stroke.
Q. What can be inferred about strokes from this passage?
C is correct because the passages explains how strokes in certain regions affect or cause a loss of certain functions. B is incorrect because the passage states that it will, “result in the loss of very specific functions,” and later states “along with the swallowing in the previous example, a stroke in that region could affect…” providing more than one bodily function that gets damaged.
Deafness is the partial or complete inability to hear. Some people are born deaf, which is known as congenital deafness. Many others begin to suffer from conductive hearing loss because of age, genetic predisposition, or environmental effects, including exposure to extreme noise (noise-induced hearing loss), certain illnesses (such as measles or mumps), or damage due to toxins (such as those found in certain solvents and metals).
Given the mechanical nature by which the sound wave stimulus is transmitted from the eardrum through the ossicles to the oval window of the cochlea, some degree of hearing loss is inevitable. With conductive hearing loss, hearing problems are associated with a failure in the vibration of the eardrum and/or movement of the ossicles. These problems are often dealt with through devices like hearing aids that amplify incoming sound waves to make vibration of the eardrum and movement of the ossicles more likely to occur.
When the hearing problem is associated with a failure to transmit neural signals from the cochlea to the brain, it is called sensorineural hearing loss. One disease that results in sensorineural hearing loss is Ménière’s disease. Although not well understood, Ménière’s disease results in a degeneration of inner ear structures that can lead to hearing loss, tinnitus (constant ringing or buzzing), vertigo (a sense of spinning), and an increase in pressure within the inner ear. This kind of loss cannot be treated with hearing aids, but some individuals might be candidates for a cochlear implant as a treatment option. Cochlear implants are electronic devices that consist of a microphone, a speech processor, and an electrode array. The device receives incoming sound information and directly stimulates the auditory nerve to transmit information to the brain.
Q. What can be inferred about Ménière’s disease from paragraph 3?
A is correct because paragraph 3 states that the disease is not well understood, which suggests that it hasn’t been studied well. D is incorrect because while the passage does state that it can lead to hearing loss, it never implies that this is the only symptom.
Long-term memory (LTM) is the continuous storage of information. Unlike short-term memory, the storage capacity of LTM has no limits. It encompasses all the things you can remember that happened more than just a few minutes ago to all of the things that you can remember that happened days, weeks, and years ago. In keeping with the computer analogy, the information in your LTM would be like the information you have saved on the hard drive. It isn’t there on your desktop (your short-term memory), but you can pull up this information when you want it, at least most of the time. Not all long- term memories are strong memories. Some memories can only be recalled through prompts. For example, you might easily recall a fact— “What is the capital of the United States?”—or a procedure—“How do you ride a bike?”—but you might struggle to recall the name of the restaurant you had dinner at when you were on vacation in France last summer. A prompt, such as that the restaurant was named after its owner, who spoke to you about your shared interest in soccer, may help you recall the name of the restaurant.
Long-term memory is divided into two types: explicit and implicit. Understanding the different types is important because a person’s age or particular types of brain trauma or disorders can leave certain types of LTM intact while having disastrous consequences for other types. Explicit memories are those we consciously try to remember and recall. For example, if you are studying for your chemistry exam, the material you are learning will be part of your explicit memory. Implicit memories are memories that are not part of our consciousness. They are memories formed from behaviors. Implicit memory is also called non-declarative memory.
Q. Which of the following can be inferred from paragraph 2 about explicit memories?
D is correct because paragraph 2 explains the importance of knowing the two types of long-term memory because they are each affected differently by age and brain trauma. The last paragraph states that implicit memories are more naturally formed memories that require no conscious thought to remember, thus making them easier to recall regardless of age or trauma.
Hunter-gatherer societies demonstrate the strongest dependence on the environment of the various types of preindustrial societies. As the basic structure of human society until about 10,000–12,000 years ago, these groups were based around kinship or tribes. Hunter- gatherers relied on their surroundings for survival—they hunted wild animals and foraged for uncultivated plants for food. When resources became scarce, the group moved to a new area to find sustenance, meaning they were nomadic. These societies were common until several hundred years ago, but today only a few hundred remain in existence, such as indigenous Australian tribes sometimes referred to as “aborigines,” or the Bambuti, a group of pygmy hunter-gatherers residing in the Democratic Republic of Congo. Hunter-gatherer groups are quickly disappearing as the world’s population explodes.
1. What can be inferred about hunter-gatherers?
A is correct because the end of the passage states that there are only a few hundred hunter-gatherer societies left in the world, and that the remaining ones are “disappearing as the world’s population explodes”.
Meritocracy is another system of social stratification in which personal effort—or merit—determines social standing. High levels of effort will lead to a high social position, and vice versa. The concept of meritocracy is an ideal—that is, a society has never existed where social rank was based purely on merit. Because of the complex structure of societies, processes like socialization, and the realities of economic systems, social standing is influenced by multiple factors, not merit alone. Inheritance and pressure to conform to norms, for instance, disrupt the notion of a pure meritocracy. Sociologists see aspects of meritocracies in modern societies when they study the role of academic performance and job performance, and the systems in place for evaluating and rewarding achievement in these areas.
Q. This passage suggests that meritocracy is …
B is correct because the passage states that this form of society is an idealistic one and that the complex nature of societies means that social standing is based on “multiple factors, not merit alone”.
Human movement includes not only actions at the joints of the body, but also the motion of individual organs and even individual cells. As you read these words, red and white blood cells are moving throughout your body, muscle cells are contracting and relaxing to maintain your posture and to focus your vision, and glands are secreting chemicals to regulate body functions. Your body is coordinating the action of entire muscle groups to enable you to move air into and out of your lungs, to push blood throughout your body, and to propel the food you have eaten through your digestive tract. Consciously, of course, you contract your skeletal muscles to move the bones of your skeleton to get from one place to another, and to carry out all of the activities of your daily life.
Q. The word contracting is closest in meaning to …
D is correct because contracting occurs when our muscles or something tighten. Options A and C are very similar and can, thus, be eliminated. In the context, this word is directly followed by “…and relaxing…”, so “contracting” must somehow be complementary to relaxing. In this situation, “tightening” (D) fits best.