Miniaturization
Many sci-fi stories depend upon a technology called miniaturization. Isaac Asimov’s classic Fantastic Voyage; his more scientifically rigorous sequel, Fantastic Voyage II; DC Comics featuring The Atom, and Marvel Comics featuring Antman and The Wasp.
Is miniaturization real? Could it be real? What would be the results if it was real?
Scene from the 1966 movie Fantastic Voyage. The medical ship, inside in a blood vessel, is under attack from antibodies!
Miniaturization in movies and TV
1940’s movie – Dr. Cyclops. People are reduced to less than a foot in size by the titular mad scientist, and are subjugated to his whims.
1957 movie – The Incredible Shrinking Man inspired a boom in science fiction films that made use of size-alteration.
1961 The Atom, a Silver Age comic book character, the Atom, Dr. Ray Palmer, created by DC Comics.
1960’s Ant-Man, Marvel Comics superhero.
1966 Fantastic Voyage
1976 Dr. Shrinker, from the ABC network’s The Krofft Supershow
1987 Innerspace starring stars Dennis Quaid, Martin Short and Meg Ryan.
1989 Honey, I Shrunk the Kids, 1997 Honey, We Shrunk Ourselves
2015 Ant-Man, and 2018 Ant-Man and the Wasp
2016 – DC’s Legends of Tomorrow (featuring The Atom)
What would happen if we compressed someone?
Neil deGrasse Tyson shows us the real physics.
Although he probably shouldn’t write any more comics 😉
By Clay Yount, Hamlet’s Danish, 12/9/2014
Physics: How would one try to do this?
There are no practical ways to actually do this. However, science fiction stories speculate on how this could be done.
Interestingly, sustained thought and speculation on science fiction technologies has allowed scientists to develop real-world technologies.
A. Compression / increasing density
“Why are you so certain miniaturization is impossible?”
“If you reduce a man to the dimensions of a fly, then all the mass of a man would be crowded into the volume of a fly. You’d end up with a density of something like -” he paused to think – “a hundred and fifty thousand times that of platinum. “
From Fantastic Voyage II
B. Removing atoms
“But what if the mass were reduced in proportion?” – “Then you end up with one atom in the miniaturized man for every three million in the original. The miniaturized man would not only have the size of a fly but the brainpower of a fly as well. “
From Fantastic Voyage II:
C. Changing Planck’s constant
This is a major science-plot point in Fantastic Voyage II (1988)
“And if the atoms are reduced, too?”
“If it is miniaturized atoms you are speaking of, then Planck’s constant, which is an absolutely fundamental quantity in our Universe, forbids it. Miniaturized atoms would be too small to fit into the graininess of the Universe. “
“And if I told you that Planck’s constant was reduced as well, so that a miniaturized man would be encased in a field in which the graininess of the Universe was incredibly finer than it is under normal conditions?”
“Then I wouldn’t believe you. “
“Without examining the matter? You would refuse to believe it as a result of preconceived convictions, as your colleagues refuse to believe you?”
And at this, Morrison was, for a moment, silent….
…Well over half an hour had passed before Morrison felt convinced that the objects he could see outside the ship were shrinking and were receding perceptibly toward their normal size.
Morrison said, “I am thinking of a paradox.”
“What’s that?” said Kalinin, yawning. She had obviously taken her own advice about the advisability of relaxing.
“The objects outside the ship seemed to grow larger as we shrink. Ought not the wavelengths of light outside the ship also grow larger, becoming longer in wavelength, as we shrink? Should we not see everything outside turn reddish, since there can scarcely be enough ultraviolet outside to expand and replace the shorter-wave visible light?”
Kalinin said, “If you could see the light waves outside, that would indeed be how they would appear to you. But you don’t. You see the light waves only after they’ve entered the ship and impinged upon your retina. And as they enter the ship, they come under the influence of the miniaturization field and automatically shrink in wavelength, so that you see those wavelengths inside the ship exactly as you would see them outside.”
“If they shrink in wavelength, they must gain energy.”
“Yes, if Planck’s constant were the same size inside the miniaturization field as it is outside. But Planck’s constant decreases inside the miniaturization field — that is the essence of miniaturization. The wavelengths, in shrinking, maintain their relationship to the shrunken Planck’s constant and do not gain energy. An analogous case is that of the atoms. They also shrink and yet the interrelationships among atoms and among the subatomic particles that make them up remain the same to us inside the ship as they would seem to us outside the ship.”
“But gravity changes. It becomes weaker in here.”
“The strong interaction and the electroweak interaction come under the umbrella of the quantum theory. They depend on Planck’s constant. As for gravitation?” Kalinin shrugged. “Despite two centuries of effort, gravitation has never been quantized. Frankly, I think the gravitational change with miniaturization is evidence enough that gravitation cannot be quanitzed, that it is fundamentally nonquantum in nature.”
“I can’t believe that,” said Morrison. “Two centuries of failure can merely mean we haven’t managed to get deep enough into the problem yet. Superstring theory nearly gave us out unified field at last.” (It relieved him to discuss the matter. Surely he couldn’t do so if his brain were heating in the least.)
“Nearly doesn’t count,” said Kalinin. “Still, Shapirov aagreed with you, I think. It was his notion that once we tied Planck’s constant to the speed of light, we would not only have the practical effect of miniaturizing and deminiaturizing in an essentially energy-free manner, but that we would have the theoretical effect of being able to work out the connection between quantum theory and relativity and finally have a good unified field theory. And probably a simpler one than we could have imagined possible, he would say.”
“Maybe,” said Morrison. He didn’t know enough to comment beyond that.
Surely this is complete fantasy, correct? Well, probably. But there is some room in physics to believe that the constants of nature, even Planck’s constant, may quite be constant:
Could Fundamental Constants Be Neither Fundamental nor Constant?
Are Nature’s Laws Really Universal? Dr. Michael Murphy, Centre for Astrophysics and Supercomputing,
Swinburne University of Technology
The Variability of the ‘Fundamental Constants’
The Constants of Nature: From Alpha to Omega – The Numbers That Encode the Deepest Secrets of the Universe (book,) John D. Barrow
D. Nanotechnology as miniaturization
“…The ideas and concepts behind nanoscience and nanotechnology started with a talk entitled “There’s Plenty of Room at the Bottom” by physicist Richard Feynman at an American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959, long before the term nanotechnology was used.
In his talk, Feynman described a process in which scientists would be able to manipulate and control individual atoms and molecules. Over a decade later, in his explorations of ultraprecision machining, Professor Norio Taniguchi coined the term nanotechnology. It wasn’t until 1981, with the development of the scanning tunneling microscope that could “see” individual atoms, that modern nanotechnology began.”
Nano.gov What is nanotechnology?
Nanotechnology isn’t so impossible. We already have developed techniques to image and pick atoms. one atom at a time, through technologies such as atomic force microscopy and Scanning tunneling microscopy.
References
Miniaturization: Technovelgy article
Excerpt from Fantastic Voyage: II A Novel By Isaac Asimov, 1988
Learning Standards
Next Generation Science Standards: Science & Engineering Practices
● Ask questions that arise from careful observation of phenomena, or unexpected results, to clarify and/or seek additional information.
● Ask questions that arise from examining models or a theory, to clarify and/or seek additional information and relationships.
● Ask questions to determine relationships, including quantitative relationships, between independent and dependent variables.
● Ask questions to clarify and refine a model, an explanation, or an engineering problem.
● Evaluate a question to determine if it is testable and relevant.
● Ask questions that can be investigated within the scope of the school laboratory, research facilities, or field (e.g., outdoor environment) with available resources and, when appropriate, frame a hypothesis based on a model or theory.
● Ask and/or evaluate questions that challenge the premise(s) of an argument, the interpretation of a data set, or the suitability of the design
MA 2016 Science and technology
Appendix I Science and Engineering Practices Progression Matrix
Science and engineering practices include the skills necessary to engage in scientific inquiry and engineering design. It is necessary to teach these so students develop an understanding and facility with the practices in appropriate contexts. The Framework for K-12 Science Education (NRC, 2012) identifies eight essential science and engineering practices:
1. Asking questions (for science) and defining problems (for engineering).
2. Developing and using models.
3. Planning and carrying out investigations.
4. Analyzing and interpreting data.
5. Using mathematics and computational thinking.
6. Constructing explanations (for science) and designing solutions (for engineering).
7. Engaging in argument from evidence.
8. Obtaining, evaluating, and communicating information.
Scientific inquiry and engineering design are dynamic and complex processes. Each requires engaging in a range of science and engineering practices to analyze and understand the natural and designed world. They are not defined by a linear, step-by-step approach. While students may learn and engage in distinct practices through their education, they should have periodic opportunities at each grade level to experience the holistic and dynamic processes represented below and described in the subsequent two pages… http://www.doe.mass.edu/frameworks/scitech/2016-04.pdf
Facts and Fiction of the Schumann Resonance
This has been excerpted from Facts and Fiction of the Schumann Resonance,by Brian Dunning, Skeptoid Podcast #352
It’s increasingly hard to find a web page dedicated to the sales of alternative medicine products or New Age spirituality that does not cite the Schumann resonances as proof that some product or service is rooted in science. … Today we’re going to see what the Schumann resonances actually are, how they formed and what they do, and see if we can determine whether they are, in fact, related to human health.
In physics, Schumann resonances are the name given to the resonant frequency of the Earth’s atmosphere, between the surface and the densest part of the ionosphere.
Image from nasa.gov/mission_pages/sunearth/news/gallery
They’re named for the German physicist Winfried Otto Schumann (1888-1974) who worked briefly in the United States after WWII, and predicted that the Earth’s atmosphere would resonate certain electromagnetic frequencies.
[What is a resonant frequency? Here is a common example. When you blow on a glass bottle at a certain frequency, you can get the bottle to vibrate at the same frequency]
from acs.psu.edu/drussell/Demos/BeerBottle/beerbottle.html
This glass bottle has a resonant frequency of about 196 Hz.
That’s the frequency of sound waves that most efficiently bounce back and forth between the sides of the bottle, at the speed of sound, propagating via the air molecules.
Electromagnetic radiation – like light, and radio waves – is similar, except the waves travel at the speed of light, and do not require a medium like air molecules.
The speed of light is a lot faster than the speed of sound, but the electromagnetic waves have a lot further to go between the ground and the ionosphere than do the sound waves between the sides of the bottle.
This atmospheric electromagnetic resonant frequency is 7.83 Hz, which is near the bottom of the ELF frequency range, or Extremely Low Frequency.
The atmosphere has its own radio equivalent of someone blowing across the top of the bottle: lightning.
Lightning is constantly flashing all around the world, many times per second; and each bolt is a radio source. This means our atmosphere is continuously resonating with a radio frequency of 7.83 Hz, along with progressively weaker harmonics at 14.3, 20.8, 27.3 and 33.8 Hz.
These are the Schumann resonances.
It’s nothing to do with the Earth itself, or with life, or with any spiritual phenomenon;
it’s merely an artifact of the physical dimensions of the space between the surface of the Earth and the ionosphere.
Every planet and moon that has an ionosphere has its own set of Schumann resonances defined by the planet’s size.
Biggest point: this resonated radio from lightning is a vanishingly small component of the electromagnetic spectrum to which we’re all naturally exposed.
The overwhelming source is the sun, blasting the Earth with infrared, visible light, and ultraviolet radiation.
All natural sources from outer space, and even radioactive decay of naturally occurring elements on Earth, produce wide-spectrum radio noise. Those resonating in the Schumann cavity are only a tiny, tiny part of the spectrum.
Nevertheless, because the Schumann resonance frequencies are defined by the dimensions of the Earth, many New Age proponents and alternative medicine advocates have come to regard 7.83 Hz as some sort of Mother Earth frequency, asserting the belief that it’s related to life on Earth.
The most pervasive of all the popular fictions surrounding the Schumann resonance is that it is correlated with the health of the human body.
There are a huge number of products and services sold to enhance health or mood, citing the Schumann resonance as the foundational science.
A notable example is the Power Balance bracelets. Tom O’Dowd, formerly the Australian distributor, said that the mylar hologram resonated at 7.83 Hz.
When the bracelet was placed within the body’s natural energy field, the resonance would [supposedly] “reset” your energy field to that frequency.
Well, there were a lot of problems with that claim.
First of all, 7.83 Hz has a wavelength of about 38,000 kilometers. This is about the circumference of the Earth, which is why its atmospheric cavity resonates at that frequency. 38,000 kilometers is WAY bigger than a bracelet!
There’s no way that something that tiny could resonate such an enormous wavelength. O’Dowd’s sales pitch was implausible, by a factor of billions, to anyone who understood resonance.
This same fact also applies to the human body. Human beings are so small, relative to a radio wavelength of 38,000 kilometers, that there’s no way our anatomy could detect or interact with such a radio signal in any way.
Proponents of binaural beats cite the Schumann frequency as well. These are audio recordings which combine two slightly offset frequencies to produce a third phantom beat frequency that is perceived from the interference of the two.
Some claim to change your brain’s encephalogram, which they say is a beneficial thing to do. Brain waves range from near zero up to about 100 Hz during normal activity, with a typical reading near the lower end of the scale.
This happens to overlap 7.83 — suggesting the aforementioned pseudoscientific connection between humans and the Schumann resonance — but with a critical difference. An audio recording is audio, not radio. It’s the physical oscillation of air molecules, not the propagation of electromagnetic waves. The two have virtually nothing to do with each other.
[Other salespeople claim] that our bodies’ energy fields need to interact with the Schumann resonance, but can’t because of all the interference from modern society [and so they try to sell devices that supposedly connect our body to the Schumann resonance.]
It’s all complete and utter nonsense. Human bodies do not have an energy field: in fact there’s not even any such thing as an energy field. Fields are constructs in which some direction or intensity is measured at every point: gravity, wind, magnetism, some expression of energy.
Energy is just a measurement; it doesn’t exist on its own as a cloud or a field or some other entity. The notion that frequencies can interact with the body’s energy field is, as the saying goes, so wrong it’s not even wrong.
Another really common New Age misconception about the Schumann resonance is that it is the resonant frequency of the Earth. But there’s no reason to expect the Earth’s electromagnetic resonant frequency to bear any similarity to the Schumann resonance.
Furthermore, the Earth probably doesn’t even have a resonant electromagnetic frequency. Each of the Earth’s many layers is a very poor conductor of radio; combined all together, the Earth easily absorbs just about every frequency it’s exposed to. If you’ve ever noticed that your car radio cuts out when you drive through a tunnel, you’ve seen an example of this.
Now the Earth does, of course, conduct low-frequency waves of other types. Earthquakes are the prime example of this. The Earth’s various layers propagate seismic waves differently, but all quite well. Seismic waves are shockwaves, a physical oscillation of the medium. Like audio waves, these are unrelated to electromagnetic radio waves.
Each and every major structure within the Earth — such as a mass of rock within a continent, a particular layer of magma, etc. — does have its own resonant frequency for seismic shockwaves, but there is (definitively) no resonant electromagnetic frequency for the Earth as a whole.
So our major point today is that you should be very skeptical of any product that uses the Schumann resonance as part of a sales pitch.
The Earth does not have any particular frequency. Life on Earth is neither dependent upon, nor enhanced by, any specific frequency.
Source: skeptoid.com/episodes/4352
Resonance
Resonance: The increase in the amplitude of an oscillation of a system under the influence of a periodic force whose frequency is close to that of the system’s natural frequency.
There are several types of resonance
Mechanical resonance
tendency of a mechanical system to respond at greater amplitude when the frequency of its oscillations matches the system’s natural frequency of vibration (its resonance frequency or resonant frequency) than it does at other frequencies.
This may cause violent swaying motions and potentially catastrophic failure in improperly constructed structures including bridges, buildings and airplanes.
Examples include:
Musical instruments (acoustic resonance)
Musical instruments are set into vibrational motion at their natural frequency when a person hits, strikes, strums, plucks or somehow disturbs the object.
Each natural frequency of the object is associated with one of the many standing wave patterns by which that object could vibrate. The natural frequencies of a musical instrument are sometimes referred to as the harmonics of the instrument.
Physics Classroom – Sounds – Lesson 5 – Resonance
Clocks
Most clocks keep time by mechanical resonance in a balance wheel, pendulum, or quartz crystal.
Tidal resonance
Seen at the Bay of Fundy in Canada.
Objects can shatter at resonant frequencies
A wineglass breaking when someone sings a loud note at exactly the right pitch.
Resonance in weather systems
Rossby waves, also known as planetary waves, are a type of wave naturally occurring in rotating fluids (gas or liquid.) Here on Earth are they are giant meanders in high-altitude winds; they have a major influence on weather.
It has been proposed that a number of regional weather extremes in the Northern Hemisphere associated with blocked atmospheric circulation patterns may have been caused by quasiresonant amplification of Rossby waves.
Examples include the 2013 European floods, the 2012 China floods, the 2010 Russian heat wave, the 2010 Pakistan floods and the 2003 European heat wave.
Rossyby Wave, Wikipedia
Orbital resonance
The motion of one object orbiting a star, or planet, can influence the motion of another object. Eventually, over time the motions of the objects can become in resonance with each other.
Orbital resonance can occur in many ways:
Here we see an asteroid sometimes called a quasi-satellite. It has its own orbit around the Sun, but over time this has developed a 1:1 resonance with Earth’s orbit.
The most well known quasi-satellite of Earth is the asteroid Cruithne, discovered in 1986. It is 5 KM in diameter. If you were “above” our Sun, looking down into the solar system then you would see it’s orbit and Earth’s orbit like this:
IMAGE FROM WIKIPEDIA
But from the point of view of people here on Earth, it appears to be trailing us, making a horseshoe-shaped orbit.
That’s not a moon as such, and it doesn’t even orbit us. But due to the oddities of orbital mechanics it appears to be behind us in space, orbiting empty space!
IMAGE FROM WIKIPEDIA
Resonance in the rings of Saturn
TBA
Ring dynamics, Stars and Planets, ASTR 221
The Forces that Sculpt Saturn’s Rings….
Resonance Moon and Rings, NASA Science
Staggering Structure, NASA Science
Planetary Rings, Lumen Learning
Resonance in electrical circuits
Circuits involving capacitors and inductors can demonstrate resonance.
A collapsing magnetic field from the inductor generates an electric current in its windings;
this current charges the capacitor,
hen the discharging capacitor provides an electric current that builds the magnetic field in the inductor.
This process is repeated continually. An analogy is a mechanical pendulum, and both are a form of simple harmonic oscillator.
Symbols: resistor – R, inductor – L, capacitor – C
Resonance in RLC circuits
An RLC circuit consists of a resistor, an inductor, and a capacitor.
The circuit forms a harmonic oscillator for current; it resonates similarly to an LC circuit.
The main difference (due to the presence of the resistor) is that any oscillation induced in the circuit decays over time if it is not kept going by a source.
This effect of the resistor is called damping.
The presence of the resistance reduces the peak resonant frequency of damped oscillation, although the resonant frequency for driven oscillations remains the same as an LC circuit.
Some resistance is always unavoidable in real circuits, even if a resistor is not specifically included as a separate component.
A pure LC circuit is an ideal that exists only in theory.
An important application for this type of circuit is tuning, such as in radio receivers or television sets. They are used to select a narrow range of frequencies from the ambient radio waves.
Intuitor.com The Physics of Resonance
Video LC Inductor-Capacitor Resonating Circuits by by Eugene Khutoryansky
Mechanical structure susceptible to damage from resonance
RedGrittyBrick, a physicist writing on skeptics.stackexchange.com, notes that a bridge can be susceptible to mechanical resonance:
Mechanical structures usually have one or more frequencies at which some part of the structure oscillates. A tuning fork has a well-defined natural frequency of oscillation. More complex structures may have a dominant natural frequency of oscillation.
If some mechanical inputs (such as the pressure of feet walking in unison) have a frequency that is close to a natural frequency of the structure, these inputs will tend to initiate and, over a short time, increase the oscillating movements of the structure. Like pushing a child’s swing at the right time.
One example is London’s Millennium Bridge which was closed shortly after opening because low-frequency vibrations in the bridge were causing large groups of pedestrians to simultaneously shift their weight and reinforcing the oscillation. Dampers were fitted.
Skeptics.stackexchange Does a column of marching soldiers have to break their rhythm while crossing a bridge to prevent its collapse?
Related topics (local)
Nikola Tesla and wireless power transmission
Facts and Fiction of the Schumann Resonance: On this website
Learning Standards
2016 Massachusetts Science and Technology/Engineering Curriculum Framework
HS-PS4-5. Communicate technical information about how some technological devices use the principles of wave behavior and wave interactions with matter to transmit and capture information and energy. Examples of principles of wave behavior include resonance, photoelectric effect, and constructive and destructive interference.
MCAS Science and Technology
MCAS Science and Technology 8th grade. Spring 2017. Based on learning standards in the four major content strands of the Massachusetts Science and Technology/Engineering Curriculum Framework.
MCAS Science and Tech 8th grade
• Earth and Space Science
• Life Science (Biology)
• Physical Sciences (Chemistry and Physics)
• Technology/Engineering
MCAS Evolution
MCAS Evolution
Feb 2016 MCAS. Scientists often compare fossils of extinct organisms with living organisms to help determine evolutionary relationships. What is the primary information that scientists use when comparing fossils with living organisms?
A. the types of minerals that formed the fossils
B. the size of the rocks that contained the fossils
C. the cause of death for the fossilized organisms
D. the physical characteristics of the fossilized organisms
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Feb 2016 MCAS .
The pictures below show the shells of some species of land snails found on a Pacific island. Each species was found on a different hill on the island. Based on the snails’ shell shapes, scientists made hypotheses about the evolutionary relationships among the snails. Which of the following would be the best characteristic to compare in order to test these hypotheses?
A. the size of the snails
B. the diet of the snails
C. the DNA of the snails
D. the average age of the snails
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Scientists hypothesized that several species of frogs called tiger frogs evolved from a recent common ancestor. The hypothesis was based on fossil evidence and on physical similarities among living species.
Which of the following provides the best additional support for the scientists’ hypothesis?
A. Tiger frogs have longer life spans than other frog species.
B. Tiger frogs have the same diet and all use enzymes to digest food.
C. Tiger frogs live near each other and are all preyed upon by the same predator species.
D. Tiger frogs have similarities in their mitochondrial DNA that are not shared by other frog species.
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Spring 2017
Some populations of Atlantic tomcod fish have an allele that makes the fish resistant to toxic pollutants called PCBs. Tomcod populations in several rivers were analyzed for the presence of this allele. Each river had varying levels of PCB pollution. Which of the following results would best support the conclusion that natural selection is influencing the presence of this allele in the tomcod populations?
A. All of the tomcod in each of the rivers have this allele.
B. The percentage of tomcod with this allele remains the same from year to year in each river.
C. The rivers with high PCB levels have larger percentages of tomcod with this allele than the rivers without PCBs.
D. Eggs from tomcod without this allele can hatch in rivers with or without PCBs, and eggs from tomcod with this allele can only hatch in rivers without PCBs.
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Spring 2017.
A researcher observed army ants, which form colonies with one queen ant and many worker ants. The researcher observed worker ants moving from place to place to hunt and collect a variety of food for the colony. The queen ant was observed mating with a male ant from another ant colony. The queen produced many eggs after this mating. Which of the following could help increase the genetic diversity in the colony of army ants?
A. the queen ant mating with the ant from a different colony
B. the worker ants collecting the food for the colony to eat
C. the worker ants moving from place to place
D. the queen ant eating a variety of food
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Scientists discovered a 375-million-year old fossil in Canada. The diagram below shows the top and side views of the fossil.
Which observation would best support the hypothesis that this organism was
a transitional form between amphibians and fish?
A. The fossil has a long body, which both modern amphibians and modern fish have.
B. The fossil is larger than most modern amphibians, but smaller than most ancient fish.
C. The fossil has some body structures that are similar to amphibians and some body structures that are similar to fish.
D. The fossil was discovered near a lake, which shows that the organism
needed water to reproduce, as do amphibians and fish.
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Some plants in an area produce a toxin that protects them from being eaten by a variety of insect species. The toxin decreases reproductive rates in insects. Because of a genetic mutation, some fruit flies can detect the plant toxin and therefore avoid eating the plant.
a. Describe how the number of fruit flies in the population that can detect the toxin will most likely change over the next 25 years.
b. According to the mechanism of natural selection, explain how the change you described in part (a) will occur.
c. Based on the changes in the fruit fly population, describe what will most likely happen to the plants’ production of the toxin. Explain your answer.
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Sperm whales have vestigial hip bones, and a small percentage of sperm whales
also have vestigial hind limbs. Which of the following statements best explains
the presence of these vestigial structures in sperm whales?
A. Sperm whales evolved from ancestors that walked on land.
B. Sperm whales are in the process of evolving into land mammals.
C. These structures are acquired by each individual sperm whale during its lifetime.
D. These structures resulted from sperm whales having a long period of embryonic development.
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2014 MCAS Open response question
An elephant shrew and a shrew are pictured below.
For many years, scientists had classified elephant shrews in the same family as shrews. In the 1990s, however, scientists gathered evidence for the evolutionary tree below and reclassified elephant shrews into a different family from shrews.
a. Describe the most likely reason why scientists originally classified elephant shrews with shrews.
b. Using the evolutionary tree, identify the groups to which elephant shrews are most closely related.
c. Identify and explain the evidence scientists most likely used to build the evolutionary tree and reclassify elephant shrews.
d. Identify one other type of evidence that scientists use to determine evolutionary relationships and build evolutionary trees.
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Scientists measured and recorded the average body size in a bird population over time. One year, a period of cold weather killed many of the birds. A few generations later, the scientists observed that the average body size in the population was larger than it had been before the cold weather. The scientists concluded that the population had evolved through natural selection. Which of the following would provide the best evidence to support the scientists’ conclusion?
A. The size of the bird eggs also increased over time.
B. The birds with the largest body size were the males.
C. The frequency of alleles for body size changed in the bird population.
D. The number of birds in the population had decreased by 50% or more.
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The three-spined stickleback is a species of fish. It lives in the ocean and in streams that flow into the ocean. Some scientists think that the ocean populations and stream populations may be evolving into separate species. Which of the following statements describes how speciation of these fish would most likely occur?
A. Fish from stream populations would start to reach maturity at the same time as fish from ocean populations.
B. Fish from stream populations would sometimes swim into the ocean but fish from ocean populations would stop swimming into streams.
C. Ocean populations and stream populations would each mate fewer times per year and would have decreased birth rates over time.
D. Ocean populations and stream populations would each adapt differently to their environments and would accumulate enough differences over time to prevent interbreeding
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In a certain insect species, body color varies from very light gray to very dark gray. These insects are eaten by birds that find their prey by sight. A brush fire occurs, blackening the ground where one population of this insect species lives. Which of the following is most likely to occur over the next few years?
A. The body color in the population will mutate to black.
B. The percentage of very dark gray individuals will increase.
C. The distribution of body color in the population will not change.
D. The very light gray individuals will learn how to reproduce at a later age.
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MCAS Cell biology, mitosis, meiosis, fertilization
Different types of cells in the human body undergo mitosis at different rates. Which of the following statements best explains why skin cells frequently undergo mitosis?
A. Skin cells contain molecules of DNA.
B. Skin cells constantly need to be replaced or repaired.
C. Skin cells have large numbers of sensory nerve receptors.
D. Skin cells constantly need to produce antibodies to fight off infections.
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Mice with the same parents can have different traits. Which of the following
best explains how most of these differences occur?
A. Gametes join by binary fission.
B. Cells divide by asexual reproduction.
C. Genes assort independently during meiosis.
D. Spontaneous mutations occur during mitosis.
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Which of the following is always part of normal sexual reproduction?
A. The male produces gametes by mitosis.
B. An offspring looks identical to the parents at birth.
C. The female carries only one fertilized egg at a time.
D. An offspring receives half its chromosomes from each parent.
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Various MCAS questions may be related to bacteria.
a. Identify the process that bacteria cells use to reproduce.
b. Describe two similarities between the process that skin cells use for cell division and the process that you identified in part (a).
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2015 MCAS
The illustration below shows one chromosome pair in a zygote. The zygote was produced by sexual reproduction.
Assuming normal meiosis and fertilization occurred, which illustration shows the egg and sperm that produced this zygote?
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The diagram below shows a plant cell at a particular stage in the cell cycle. This stage occurs immediately after which cellular process?
A. crossing over
B. DNA replication
C. fertilization
D. mitosis
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2016 MCAS
Which of the following must occur before mitosis can begin?
A. DNA must be replicated in the nucleus.
B. RNA must move to the center of the nucleus.
C. Chromosomes must attach to the cell membrane.
D. Ribosomes must move to opposite sides of the cell.
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Each summer, up to 40% of the lobsters in a certain area lose one of their claws due to injury. By late fall, the missing claw usually begins to grow back. Which of the following describes the process by which lobsters grow new claws?
A. Lysosomes fuse together to recycle matter to build a new claw.
B. Mitotic cell division adds new cells to rebuild the lobster’s claw.
C. Facilitated diffusion moves body cells from the remaining claw to the new claw.
D. Cellular respiration creates nutrients to enlarge existing cells in the lobster’s claw.
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2014 MCAS
Sharks typically reproduce sexually. A particular female shark, however, gave birth in a zoo despite having no recent contact with a male shark.
a. Identify the type of cell division that produces eggs and sperm in animals such as sharks.
b. Describe what normally happens during fertilization in animals such as sharks. Be sure to identify the end product of fertilization.
Female sharks can store sperm after mating and then wait to fertilize their eggs.
Scientists investigated whether the female shark in the zoo did this.
c. Describe how DNA analysis can determine if the shark reproduced using stored sperm or if she reproduced asexually. Be sure to include the source(s) of DNA being analyzed and the results of the analysis in your answer.
d. Explain why sexual reproduction is important for the long-term survival of shark species.
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2016 MCAS open response question
The diagram below represents a plant cell with three structures labeled X, Y, and Z.
Plant cells and fungal cells have many of the same types of organelles. Structures X and Y are found in both plant cells and fungal cells. Structure Z is found in plant cells, but not in fungal cells.
a. Identify structure Y and describe its main function.
b. Identify structure Z and explain how plants use this structure to survive.
c. Explain how fungi can survive without structure Z
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Each summer, up to 40% of the lobsters in a certain area lose one of their claws due to injury. By late fall, the missing claw usually begins to grow back. Which of the following describes the process by which lobsters grow new claws?
A. Lysosomes fuse together to recycle matter to build a new claw.
B. Mitotic cell division adds new cells to rebuild the lobster’s claw.
C. Facilitated diffusion moves body cells from the remaining claw to the new claw.
D. Cellular respiration creates nutrients to enlarge existing cells in the
lobster’s claw.
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2017 MCAS
The diagram below shows a chloroplast and some of the components of the reactions that occur in chloroplasts.
Which of the following is a product of the reactions that take place in a chloroplast?
A. hydrogen gas B. nitrate C. oxygen gas D. protein
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In which of the following ways does the plasma membrane regulate the entry of molecules into a cell?
A. The membrane allows only certain molecules to move into the cell.
B. The membrane destroys most molecules so that they do not enter the cell.
C. The membrane changes only certain molecules into ions before they move into the cell.
D. The membrane allows most molecules to transfer energy to the cell without entering the cell.
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Many animals have either internal or external skeletons that provide support and structure. Which of the following parts of plant cells play a similar role?
A. cell membranes
B. cell walls
C. chloroplasts
D. cytoplasm
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Sample response: Sharks typically reproduce sexually.
Meaningless words in food science
4 meaningless words: toxin, natural, organic, and GMO
Archived for my students. From The Logic of Science, 8/16/2016
News articles and blog posts are often full of buzzwords that are heavy on emotional impact but light on substance, and for scientific topics such as nutrition, health, medicine, and agriculture, four of the most common buzzwords are “toxins,” “natural,” “organic,” and “GMO.”
These words are used prolifically and are typically stated with clear implications (“toxin” and “GMO” = bad; “natural” and “organic” = good).
The problem is that these words are poorly defined and constantly misused.
They are often used in a way that shifts them into the category of what are referred to as “weasel words,” meaning that their use gives the impression that the author said something concrete and meaningful, when in fact the statement was a null sentence that lacked any real substance.
“Toxins”
Our society seems to be obsessed with “toxins.” The internet is full of purveyors of woo selling everything from expensive fruit cleanses to “earthing” mats, all with the intended purpose of ridding your body of vaguely defined “toxins.”
The problem is simply that there is no such thing as a “toxin.” All matter is made of chemicals (excluding subatomic particles for a minute), and essentially all chemicals are safe at a low enough dose and toxic at a high enough dose (i.e., the dose makes the poison).
So there are toxic doses not toxic chemicals. Even water becomes lethally toxic at a high enough dose (Garigan and Ristedt 1999). So this idea that something is going to rid your body of “toxins” doesn’t make any sense, because the chemicals themselves are not “toxins,” and they only become toxic at a high enough dose.
Take formaldehyde, for example. I often hear people talk about it as a “toxin,” but the reality is that it is an inevitable bi-product of normal biological processes. So not only is it in many fruits and vegetables, but it is actually produced by your body! The chemical itself is not dangerous, but it can become dangerous at a high enough dose.
To be clear, I’m not saying that we shouldn’t pay attention to what we put into our bodies. Of course we should, but we need to evaluate chemicals based on the dose at which they become toxic, not simply based on whether or not they are present.
Addendum (16-Aug-16): “Toxin” does have an actual biological meaning in the context of chemicals that are released by microscopic organisms. These are often toxic to individual cells at incredibly low doses because a cell itself is so small. So when I talked about “toxins” in the post, I was referring to the notion that certain chemicals are automatically dangerous for you as an organism, rather than on a cell by cell basis.
“Natural”
The definition of “natural” seems obviously to be, “found in nature,” but that’s actually a lot more ambiguous and arbitrary than it sounds. First, let’s deal with why this definition is arbitrary, and the best way to explain that is by talking about chemical compounds.
Everything around you is made of chemicals (including you)
In chemistry, a compound is simply the combination of two or more different elements. So most of the things that are around you are in fact chemical compounds (there are several thousand compounds that make your body, for example).
Now, many people like to distinguish between “natural” and “synthetic” chemicals, where “natural” chemicals can be found in nature, while “synthetic” ones were produced in a lab, but that distinction is arbitrary. A chemical is a chemical, and on a molecular level, there is nothing that separates natural and synthetic chemicals.
All chemical compounds are made by stringing different elements together, and there is no inherent difference between nature stinging elements together and scientists stringing elements together. We can make acids in the lab and you can find acids in nature, we can make chemicals that are poisonous at anything but a low dose in the lab, and you can find chemicals that are poisonous at anything but a low dose in nature, etc.
The fact that something was synthesized in a lab doesn’t make it any more dangerous or any safer than a chemical that was found in nature.
Consider, for example, acetylsalicylic acid and salicylic acid. One of those is natural and the other is synthetic.
Can you tell which? No, and neither could a chemist. If you showed those two molecules to a chemist who had no prior information about those chemicals, there is no way they she could tell you which was natural and which was synthetic, because that distinction is arbitrary.
In all likelihood though, she would know which is which because these are two very well-known compounds. Salicylic acid is the compound in willow bark that gives it medicinal value, and acetylsalicylic acid is the synthetic version of it that we all know as aspirin.
Further, we switched to the synthetic version largely because straight salicylic acid has a lot of unpleasant side effects like gastrointestinal problems (Hedner and Everts 1997).
To be clear, aspirin has side effects as well (as do all chemicals), but they tend to be less severe, and the point is, once again, that simply being natural doesn’t automatically make something better. Indeed, asserting that something is better because it is natural is a logical fallacy known as an appeal to nature.
Moving beyond the arbitrariness of what is natural, the typical definition of “found in nature” doesn’t apply to some things that most people would intuitively think of as natural.
Take apples, for example. They’re natural, right? Not so much. The fruit that we know as an apple does not grow in nature. As I will talk about more later, essentially all of our crops have been modified by thousands of years of careful breeding, so, technically speaking, they aren’t natural.
The situation is even more problematic when we talk about actions rather than objects. People often say things like, “we should do X, because X is natural,” but what on earth does that mean?
Generally, I hear people say that it means what our ancestors did, but that raises the obvious question of how far back do we have to go for something to be natural? Are we talking about 200 years ago? 1,000 years ago? 10,000 years ago? etc. This definition is horribly ambiguous.
To get around this problem, some people say that natural actions are those that are found in the animal kingdom, but that is also an extremely problematic definition for a number of reasons.
First, how widespread does it need to be in the animal kingdom? Is it simply required to find one animal that does it? Further, there are lots of human actions that most people think of as natural, even though other animals don’t do them. For example, we cook our food. Does that making cooking unnatural?
Finally, this definition is fundamentally flawed because we are just highly evolved animals, so doesn’t that make everything that we do natural? Actually think about this for a second. I think that we can all agree that structures like bird nests and beaver dams are natural, but those are not structures that just form spontaneously in nature. Rather, they are carefully and deliberately constructed by an animal who uses materials to make them.
Nevertheless, if I make a wooden table, most people would agree that the table is unnatural, but how on earth is that any different from a beaver dam? The beaver is an animal that took materials found in nature and combined them to make a new structure, and I am an animal that took materials found in nature and combined them to make a new structure. What’s the difference?
Further, we can logically extend this to all human structures. When you get right down to it, all of the parts of a skyscraper came from nature, and there is no logical reason to say that a beaver combining sticks and mud to make a dam is natural but me combing two metals to make steel is unnatural. Again, the definition of natural is completely arbitrary and functionally meaningless.
“GMO”
GMO stands for “Genetically Modified Organism,” and you may think that this has a very clear and precise definition…but it really doesn’t. Before reading the rest of this, try to come up with a definition of it yourself, then see how that definition holds up.
The most general line of thought would be that a GMO is exactly what is says: “an organism whose genes have been altered,” but that definition is much too broad.
Every living organism has a genetic code that has been altered from its ancestral state by millions of years of evolution. If you really think about it, we are all just heavily modified cyanobacteria (cyanobacteria [or some similar organisms] where most likely the first living cells).
Now you may think that I am stretching things a bit here, and perhaps I am, but “nature” does all sorts of crazy things like hybridizing species (as plants do frequently) and even stealing the DNA from one organism and inserting it into the genetic code of another.
For example, at some point in the evolution of the sweet potato, it managed to modify its genetic code by inserting bacterial genes into its DNA. In other words, it is a transgenic species whose genetic code is a combination of the genes of several species. Shouldn’t that make it a GMO?
Further, this is not limited to sweet potatoes, because bacteria themselves are well known for their ability to incorporate the DNA of other species into their own genomes. So nature is constantly doing the types of things that most people would associate with GMOs, and foods like sweet potatoes really are transgenic species.
Nevertheless, you can try to qualify the term GMO by saying that GMOs are, “organisms that have been genetically modified by humans,” but that definition is also fraught with problems. Beyond the fact that it is totally arbitrary (see the “natural” section), it also would encompass all modern agriculture.
Those delicious fruits that you know as watermelons don’t exist in nature (at least not in their current form). Similarly, natural bananas are small and full of giant seeds, and wild corn does not produce those nice juicy husks that you slather in butter and salt. Both our livestock and crops have been genetically modified through years selective breeding, and they contain genetic codes that aren’t found in nature.
[All the “natural” corn we eat has been extensively genetically modified by thousands of years of artificial selection.]
At this point, people often try to add something about moving genes between species, but that just creates more problems. First, nature does that as well…
Second, that would also include lots of “non-GMO” crops such as pluots, plumcots, tangelos, etc. all of which are hybrids that used selective breeding to combine the DNA of two different species.
Given the problems with that definition, you might try defining a GMO as an organism that is “modified by humans via a method other than selective breeding,” but that definition includes mutation breeding, which is typically not considered to be a GMO.
This method uses chemicals or UV radiation to randomly mutate organisms’ DNA in order to produce new and useful traits (i.e., it makes genetic modifications via inducing mutations). However, this method typically does not receive the label “GMO,” and in some cases, even farms that label themselves as “organic” can us crops that were produced by this method.
This leaves us with the outrageous definition that a GMO is, “an organism whose DNA was modified by humans via a method other than selective breeding or mutation breeding,” but at that point we have tacked so many arbitrary qualifiers onto the term, that the term itself is essentially meaningless.
“Organic”
Finally, let’s talk about the term “organic.” This is perhaps the greatest marketing term ever coined, and the problem with it is not that a definition doesn’t exist, but rather that the definition is arbitrary and most people don’t use it correctly (to be clear, I am talking specifically about organic farming practices, not organic chemistry.)
Here is a question for you, true or false, organic farming doesn’t use pesticides?
Organic farmers absolutely use pesticides, and many of those pesticides are toxic at comparable doses to the pesticides used in traditional farming.
Indeed, organic pesticides have can harm wild species, pollute waterways, and do all of the other harmful things that traditional pesticides can do (Bahlai et al. 2010). In fact, one of the most common organic pesticides is “Bacillus thuringiensis (Bt) toxin,” which is the exact same chemical that GMO corn produces (i.e., Bt maize).
So one the one hand, organic farmers use Bt liberally, and on the other hand, they demonize corn that produces Bt. Are you starting to see why this is arbitrary ?
So if organic crops use potentially dangerous pesticides just as much as traditional crops, then what exactly does it take for a crop to be considered organic? Generally speaking, they have to be grown without synthetic pesticides (“natural” are fine) and without the use of GMOs (some countries place additional requirements like no petroleum-based fertilizers). …
Yet distinction between “natural” and “synthetic” chemicals is arbitrary and all chemicals are safe at a low dose and toxic at a high enough dose… and the term GMO is really arbitrary. So, since the definition of organic relies on those other terms, the “organic” label is itself arbitrary.
To put this another way, organic crops are not automatically healthier or more nutritious than traditional crops. Indeed, reviews of the literature have been unable to find consistent and compelling evidence that organic food is healthier (Smith-Spangler et al. 2012; Galgano et al. 2015).
Now, at this point, you may be thinking that organic crops aren’t healthier, but surely they are better for the environment. However, that is also a misnomer. Some practices that are typically associated with organic farming are better for the environment, but those practices are sometimes included in non-organic farming as well, and organic farming has serious drawbacks, such as the fact that it often uses far more land and resources than traditional farming (Tuomisto et al. 2012).
As a result, you can’t make a blanket statement like, “organic farming is better for the environment” because in many cases it isn’t.
The point is that simply saying that something is “organic” doesn’t actually tell you anything useful about how healthy it is or whether or not it was grown in a sustainable way.
Also see https://thelogicofscience.com/2015/11/16/the-real-frankenfoods/
Citations
Bahlai et al. 2010. Choosing organic pesticides over synthetic pesticides may not effectively mitigate environmental risk in soybeans. PLoS ONE 5:e11250.
Doucleff. 2015. Natural GMO? Sweet potato genetically modified 8,000 years ago. NPR: Food and Culture
Garigan and Ristedt 1999. Death from hyponatremia as a result of acute water intoxication in an Army basic trainee. Military Medicine 164:234–238.
Galgano et al. 2015. Conventional and organic foods: A comparison focused on animal products. Cogent Food and Agriculture 2: 1142818.
Hedner and Everts 1997. The early clinical history of salicylates in rheumatology and pain. Clinical Rheumatology 17:17–25.
Ruishalme. 2015. Natural assumptions. Thoughtscapism.com. Accessed 15-Aug-16
Smith-Spangler et al. 2012. Are organic foods safer or healthier than conventional alternatives? A systematic review. Annals of Internal Medicine 157:348–366.
Tuomisto et al. 2012. Does organic farming reduce environmental impacts? A meta-analysis. Journal of Environmental Management, 112:309–320.
Wilcox. 2011. Mythbusting 101: Organic farming > conventional agriculture. Scientific American.
Related articles
Meaningless words in food science
Nutrients
Organic food and farming
Meaningless words in food science
What we need to know about healthy diets
Healthy meal generator
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MCAS Anatomy and Physiology
Feb 2016 MCAS. Mature red blood cells in mammals contain the protein hemoglobin but do not contain a nucleus. The nucleus is lost as the red blood cell matures.
Which of the following can be concluded about mammalian red blood cells from this information?
A. The cells store their DNA in ribosomes.
B. The cells have no functionality once the nucleus is lost.
C. The cells divide by meiosis to produce more red blood cells.
D. The cells perform transcription and translation before the nucleus is lost.
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Secretions from the pancreas contain compounds called lipases. Lipases increase the rate of digestion of lipids. Lipases are an example of which of the following?
A. enzymes
B. hormones
C. nucleic acids
D. simple sugars
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Each part of the human digestive system has a specific function. Which of the
following activities best models the role of the esophagus?
A. shaking a small piece of chalk in a plastic bottle
B. cutting a clay cube into smaller and smaller cubes
C. squeezing a small greased ball through plastic tubing
D. placing a small piece of egg in dilute hydrochloric acid
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Here are some problems associated with four organs of the human digestive system.
1 Acid inside this organ begins to dissolve some of its tissue lining.
2 An infection prevents the movement of nutrients through this organ’s walls into the bloodstream.
3 Inflamed tissue prevents the smooth passage of food through this organ
after swallowing.
4 Swelled-up veins make eliminating wastes from this organ difficult.
Which organ is most likely the stomach?
A. organ 1 . B. organ 2 C. organ 3 D. organ 4
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Feb 2016 MCAS: At high altitudes, air is less dense than at sea level because of decreased air pressure. This means that a person who ascends to high altitudes takes in fewer oxygen molecules per breath.
a. Describe and explain an immediate response that occurs in the respiratory system when a person first reaches high altitudes.
b. Describe and explain an immediate response that occurs in the circulatory system when a person first reaches high altitudes.
If a person lives at high altitudes for an extended period of time, other body responses occur. One response is an increase in the number of red blood cells.
c. Explain how this response is helpful to the body.
At high altitudes, air temperature is also generally colder than at sea level.
d. Describe and explain one internal body response that occurs when a person has been outside long enough for his core temperature to drop.
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The heart is part of the circulatory system.The heart is part of the circulatory system.
a. Describe the primary function of the heart.
Medical researchers are working on developing artificial hearts. Three of the many requirements for the design of an artificial heart are listed below.
• An artificial heart must connect to the pulmonary artery (artery connected to the lungs).
• An artificial heart must connect to the superior vena cava and inferior vena cava(large veins).
• An artificial heart must be able to function at different speeds when a person is exercising and is at rest.
b. Describe how each of the requirements listed above would help the body of an individual with an artificial heart function normally.
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In the human heart, a group of cells in the wall of the right atrium produces nerve impulses that stimulate cardiac muscle. What do these nerve impulses directly control?
A. the amount of oxygen in the blood
B. the release of platelets into the blood
C. the speed at which the heart pumps blood
D. the path blood takes when it leaves the heart
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Low blood pressure can be life-threatening. To help maintain a stable blood pressure, receptors in the heart detect changes in blood pressure. Information about blood pressure changes is then sent to the brain. If blood pressure is too low, the brain sends a message to the heart to beat faster. Based on this information, which of the following systems are directly involved in keeping blood pressure stable?
A. circulatory, muscular, nervous
B. circulatory, immune, skeletal
C. excretory, immune, muscular
D. excretory, nervous, skeletal
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When astronauts are in low-gravity environments, their bodies begin to release stored calcium. As a result, which of the following most likely occurs when an astronaut returns to Earth?
A. The risk of inflamed tendons increases.
B. The chance of breaking a bone increases.
C. The stomach’s level of functioning decreases.
D. The blood’s ability to carry oxygen decreases.
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During exercise, a person’s muscles need a constant supply of ATP. To meet this need, the rate of which of the following processes increases?
A. cellular respiration
B. mitosis
C. protein synthesis
D. transcription
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Feb 2016 MCAS. When astronauts are in low-gravity environments, their bodies begin to release stored calcium. As a result, which of the following most likely occurs when an astronaut returns to Earth?
A. The risk of inflamed tendons increases.
B. The chance of breaking a bone increases.
C. The stomach’s level of functioning decreases.
D. The blood’s ability to carry oxygen decreases.
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Feb 2016 MCAS. An altered form of the structural protein collagen causes a condition in which bones are weak and break easily. Which of the following are components of collagen?
A. amino acids . B. fatty acids . C. monosaccharides . D. nucleotides
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Secretions from the pancreas contain compounds called lipases. Lipases increase the rate of digestion of lipids. Lipases are an example of which of the following?
A. enzymes B. hormones C. nucleic acids D. simple sugars
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Feb Biology MCAS 2016
The axons of some vertebrate neurons are wrapped with special cells called Schwann cells, as shown below.
Which type of signal jumps from node to node between the Schwann cells to move down the axon?
A. a digital pulse B. a magnetic pulse
C. an electrical signal D. a glycoprotein signal
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Base your answers to questions 35 through 37 on the diagram below
and on your knowledge of biology.
35. The process represented in the diagram best illustrates
(1) cellular communication
(2) muscle contraction
(3) extraction of energy from nutrients
(4) waste disposal
36. Which statement best describes the diagram?
(1) Nerve cell X is releasing receptor molecules.
(2) Nerve cell Y is signaling nerve cell X.
(3) Nerve cell X is attaching to nerve cell Y.
(4) Nerve cell Y contains receptor molecules for substance A.
37. A drug is developed that, due to its molecular shape, blocks the action of substance A. Which shape would the drug molecule most likely resemble?
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Base your answers to questions 56 through 58 on the diagram below.
56 In region F, there is a space between nerve cells C and D.
Cell D is usually stimulated to respond by:
(1) a chemical produced by cell C moving to cell D
(2) the movement of a virus from cell C to cell D
(3) the flow of blood out of cell C to cell D
(4) the movement of material through a blood vessel that forms between cell C and cell D
57 If a stimulus is received by the cells at A, the cells at E will most likely use energy obtained from a reaction between
(1) fats and enzymes (3) glucose and oxygen
(2) ATP and pathogens (4) water and carbon dioxide
58 State one possible cause for the failure of muscle E to respond to a stimulus at A.
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A high respiratory rate usually indicates that a person’s body needs more
A. antibodies.
B. carbon dioxide.
C. oxygen.
D. platelets.
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The human skeletal system has many important functions, including movement. As a person ages, movement can become difficult. Ligaments become less elastic and cartilage is damaged.
a. Considering the function of ligaments, explain why less elastic ligaments could cause movement to be difficult.
b. Considering the function of cartilage, explain why damaged cartilage could cause movement to be difficult.
c. Identify two functions of the skeletal system besides movement.
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Which of the following structures transmits nerve impulses between the
brain and most motor and sensory neurons?
A. carotid artery
B. diaphragm
C. esophagus
D. spinal cord
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2009 MCAS
The hormones glucagon and insulin are produced by the pancreas and regulate the amount of glucose in the blood. Glucagon stimulates liver cells to release glucose into the blood, whereas insulin stimulates body cells to absorb glucose from the blood.
a. Describe and explain what will happen in the body to regulate the amount of glucose in the blood shortly after a person eats a sugary snack.
b. Describe and explain what will happen in the body to regulate the amount of glucose in the blood after a person has not eaten for several hours.
c. Discuss how your answers to parts (a) and (b) relate to the concept of homeostasis.
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Laboratory tests can be used to evaluate how well a person’s liver is working. One test measures how well the liver removes a substance called bilirubin from the blood. Based on this information, which of the following describes bilirubin?
A. an antibody
B. an energy source
C. a vitamin
D. a waste product
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Which of the following statements describes a function of the human brain?
A. It produces ATP for organs but not for muscles.
B. It controls voluntary actions but not involuntary actions.
C. It is responsible for removing toxic compounds from the blood.
D. It is the main center for sensory and motor processing in the body.
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In humans, the first seven pairs of rib bones are connected to the sternum (breastbone) by cartilage. Which of the following statements describes the main reason why cartilage is important in these bone-to-bone connections?
A. The cartilage keeps the bones from touching the heart.
B. The cartilage pulls on the ribs to draw air into the lungs.
C. The cartilage makes the rib cage flexible enough to expand during breathing.
D. The cartilage provides a location for the diaphragm muscle to attach to the lungs.
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The diagram below shows a system in the human body. Four parts of the system are
numbered.
Which of the following correctly identifies the four numbered parts?
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Growth hormone, estrogen, and thyroxine are some hormones secreted by endocrine glands. What is the role of these hormones?
A. to generate nerve impulses
B. to regulate body functions
C. to directly supply energy to cells
D. to directly remove toxins from the body
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2014 MCAS question on anatomy and homeostasis
The human body works to keep its blood glucose level within a narrow range. The hormones insulin and glucagon have important roles in this process: insulin decreases the blood glucose level, and glucagon increases the blood glucose level. Many different factors, including exercise, can affect a person’s blood glucose level.
a. Describe how a healthy person’s blood glucose level most likely changes after 45 minutes of intense exercise. Explain your answer.
b. Based on your answer to part (a), describe how a healthy person’s body responds to restore homeostasis with regard to blood glucose after exercising.
c. Describe another example of how exercise disrupts homeostasis in the body and how the body responds to restore homeostasis.
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MCAS Ecology
Feb 2016 MCAS: In the past, coyotes lived throughout the western prairies and central Rocky Mountains in North America. Over time, the coyotes’ range has expanded. Humans have tried trapping and hunting coyotes to decrease their numbers. However, biologists currently estimate the number of coyotes to be at an all-time high. Which of the following statements best explains why the number of coyotes continues to increase despite increases in death rates due to hunting and trapping?
A. Coyote lifespan is increasing, so only the oldest coyotes encounter hunters or trappers.
B. Coyote birth rates remain high, so more coyotes are added to the population than are removed.
C. Coyotes are migrating more often, so male coyotes have more fights over territories.
D. Coyotes have to compete with more species, so the coyote emigration rate has increased.
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Feb 2016 MCAS.
Here are the ecological roles of several organisms in a rainforest ecosystem.
fig tree – producer
jaguar – secondary consumer
mango tree – producer
monkey – primary consumer
toucan bird – primary consumer
a. In your Student Answer Booklet, draw a food web that includes all the organisms listed here. . Make sure the arrows represent the correct direction of energy flow.
Decomposers, such as bacteria, are not listed here:
b. Describe the role of decomposers in the rainforest ecosystem.
c. Describe what would most likely happen to producer populations and consumer populations if all decomposers in an ecosystem were removed. Explain your answer for each type of population.
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Spring 2017
The graph below shows the changes in the population size of a mammal
species introduced onto an isolated island in 1957.
Which of the following conclusions is best supported by the data?
A. Every year, more individuals were born than died.
B. A predator of this mammal was removed from the island in 1990.
C. The population decreases were the result of low immigration rates.
D. In the 1980s, the mammal’s population size stayed around its carrying capacity.
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The graph below shows changes that occurred in the size of a population of animals over a year.
Which of the following is best supported by the graph?
A. Between month 1 and month 5, the immigration rate was zero.
B. Between month 4 and month 6, a predator was introduced into the ecosystem and increased the death rate.
C. Between month 5 and month 7, the birth and emigration rates decreased and the death and immigration rates increased.
D. Between month 8 and month 12, the birth and immigration rates equaled the death and emigration rates.
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A female Hymenoepimecis wasp will temporarily paralyze a spider and then lay an egg on the spider’s abdomen. After the paralysis wears off, the spider resumes its normal activity. When the egg hatches, the larva grows by sucking its required nutrients from the spider. What type of relationship exists between the spider and the Hymenoepimecis wasp?
A. commensalism
B. mutualism
C. parasitism
D. predator-prey
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Spring 2017
A food web is shown below:
An organism in the food web is labeled X.
a. Identify and describe the ecological role of organism X in the food web.
b. Identify the organism in the food web whose population size would likely increase the
most if the bat became extinct. Explain your answer.
There are many types of relationships between organisms, including competitive and
predator-prey relationships.
c. Identify two organisms in the food web that have a competitive relationship. Explain your answer.
d. Identify two organisms in the food web that have a predator-prey relationship. Explain your answer.
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Which of the following statements best explains why introduced species often threaten native species in an ecosystem?
A. Introduced species often have less genetic diversity than native species.
B. Introduced species often lack natural predators in their new environment.
C. Introduced species often form mutualistic relationships with native species.
D. Introduced species often cause short-term droughts in their new environment.
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Spring 2017
Red lionfish have been introduced into the Caribbean Sea and the Gulf of Mexico. The red lionfish are predators that compete with native fish for space and food, causing coral reef fish population sizes to decrease. Government and environmental groups are encouraging coastal communities to catch red lionfish and serve them at restaurants.
Which of the following best explains how catching and eating red lionfish could help preserve coral reefs?
A. Reef fish will learn that red lionfish are no longer dangerous.
B. Red lionfish will return to their native habitats to avoid being caught.
C. Humans will fill the role of predator and control the red lionfish population.
D. Restaurants that serve red lionfish will attract more tourists to visit coral reefs.
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Approximately 250 million years ago, over 90% of species living in the oceans became extinct. Which of the following conditions most likely contributed to this mass extinction?
A. changes in global climate
B. evolution of new parasite species
C. mutation of species’ DNA sequences
D. increases in the rates of photosynthesis
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Biologists studied a population of lizards. They found that small lizards had trouble defending their territories and that large lizards were more likely than small or medium lizards to be preyed upon by owls. Which of the following graphs represents the most likely distribution for body size in this lizard population?
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MCAS 2014 Open Response
The Elk Mortality graph shows changes in elk mortality with wolves present and without
wolves present.
a. Summarize what the Elk Mortality graph shows about elk mortality from November to April with wolves present and without wolves present.
Based on these data, scientists can estimate the size of scavenger populations through the winter. The graph below shows the size of a scavenger population with wolves present and without wolves present.
b. Explain the cause of these data patterns for the scavenger population.
c. Describe one way that the wolves’ effect on the elk population could benefit organisms other than scavengers in the ecosystem.
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In a certain population, the death rate is greater than the birth rate from year 1 to year 2, and the immigration rate equals the emigration rate. Which of the following graphs represents this information?
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Many individuals in wild animal populations die at a young age. Which of the following factors most directly limits lifespan and therefore has a large effect on a species’ population size?
A. low birth rate
B. low immigration rate
C. high prey numbers
D. high predator numbers
MCAS Bacteria Viruses and Fungi
Spring 2017 MCAS. Show all your work (diagrams, tables, or computations) in your Student Answer Booklet. If you do the work in your head, explain in writing how you did the work. Write your answer in the space provided in your Student Answer Booklet.
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A population of S. epidermidis decreases the population sizes of other types of bacteria on the skin.
a. Describe one way decreasing the population sizes of other bacteria on the skin helps the S. epidermidis population.
b. Identify the process that S. epidermidis cells use to reproduce.
c. Describe two similarities between the process that skin cells use for cell division and the process that you identified in part (b).
When S. epidermidis moves from the skin into the body, it behaves like an invasive species entering a new ecosystem.
d. Will the S. epidermidis population size decrease, increase, or stay the same after the bacteria enter the body? Using your knowledge of invasive species, explain your answer
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Spring 2017
Topics: Biochemistry, Protista, Classification
Diatoms are marine organisms with unique cell walls that contain the element silicon. Which of the following are two common elements found in the cells of diatoms?
A. aluminum and magnesium
B. helium and hydrogen
C. mercury and neon
D. nitrogen and phosphorus
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The human body contains diverse types of bacteria. Scientists estimate that the average healthy adult human body is home to at least 10,000 species of bacteria. In fact, there are about 10 times more bacterial cells than human cells in the human body.
Many bacterial populations are important to the normal functioning of human body systems. For example, some bacteria in the digestive system produce substances the human body cannot produce. These substances help the body break down and absorb nutrients. However, bacteria that help the human body in one location can cause serious illness if introduced to a different part of the body.
8. This bacteria, S. epidermidis, can sometimes infect wounds. The symptoms of the infection include swelling, pain, pus, skin that is warm to the touch, and redness at the
infection site. Based on the symptoms, which of these human body systems work together to restore homeostasis?
A. circulatory system and immune system
B. immune system and reproductive system
C. skeletal system and respiratory system
D. respiratory system and nervous system
9. Which of the following is a characteristic that distinguishes viruses from B. thetaiotaomicron and S. epidermidis?
A. Viruses lack mitochondria.
B. Viruses lack genetic material.
C. Viruses are unable to accumulate mutations.
D. Viruses are unable to reproduce outside of host cells.
10. Which of the following best explains how antibiotic resistance spreads through
some populations of S. epidermidis?
A. All S. epidermidis cells exposed to antibiotics respond by developing mutations.
B. Some S. epidermidis cells exposed to antibiotics survive and pass their genes on to their offspring.
C. Exposure to antibiotics causes S. epidermidis cells to learn simple behaviors that help the cells survive.
D. Exposure to antibiotics causes an increase in the respiration rate of S.epidermidis cells living on the skin.
11. Which of the following describes one way B.thetaiotaomicron helps in digestion?
A. It breaks down lipids into fatty acids.
B. It breaks down proteins into amino acids.
C. It breaks down polysaccharides into simpler sugars.
D. It breaks down nucleic acids into nitrogenous bases.
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Mini-essay question:
A population of S. epidermidis decreases the population sizes of other types of bacteria on the skin.
a. Describe one way decreasing the population sizes of other bacteria on the skin helps the S. epidermidis population.
b. Identify the process that S. epidermidis cells use to reproduce.
c. Describe two similarities between the process that skin cells use for cell division and the process that you identified in part (b).
When S. epidermidis moves from the skin into the body, it behaves like an invasive species entering a new ecosystem.
d. Will the S. epidermidis population size decrease, increase, or stay the same after the bacteria enter the body? Using your knowledge of invasive species, explain your answer.
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Feb 2016 MCAS. Medicines called antifungals are used to treat infections caused by fungi. One way antifungals work is by targeting cell parts that are present in fungal cells but not in human cells.
c. Identify one cell part other than a ribosome or a plasma membrane that human cells and fungal cells have in common.
d. Describe what would happen to a human cell if the cell part you identified in part (c) were affected by an antifungal. Explain your answer based on the function of the cell part.
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