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2016 Junction City High School Summer Reading Assignments Grade 8 Please Note: These assignments were distributed to each student in a blue folder the last week of school. ALL 8TH GRADERS Read all four science-themed articles and complete the corresponding questions. Be ready to turn in completed assignments to your science teacher on the first day of school in August. Nonfiction Science Articles [distributed to each student in a Blue Folder] o “Biosphere 2: An Experiment in Isolation” o “Limiting Factors” o “Particles in Motion” o “The Crater that Ended the Reign of the Dinosaurs” PRE-AP 8TH GRADE In addition to the reading assignment for all 8th graders, read the Short Story “Flowers for Algernon” by Daniel Keyes and complete the attached assignments. Be ready to turn in completed assignments to your English teacher on the first day of school in August. Short Story Map Short Story Character Sheet Short Story Response #1 Short Story Response #2 Finalized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n Experiment in Isolation Can human beings live in an airtight building for 2 years with no life support except for the organisms they bring inside with them? Can they set up an ecosystem that provides for their every need and the needs of the other populations around them? These were the big questions that Biosphere 2 was built to answer. In 1984 construction began on the world’s largest isolated environment. The location was the Sonoran Desert, a short distance north of Tucson in Arizona. This part of the country experiences a high percentage of days without cloud cover. Sunshine is essential for an experimental ecosystem because it is the only energy source to sustain the humans and hundreds of other species in the closed system. One critically important factor was sealing the 3.1-acre live-in terrarium from the outside environment. That means no gases or organisms entering or leaving the system. First a 500-ton stainless-steel liner was laid down to isolate Biosphere 2 from the earth. Then a massive glass, steel, and concrete greenhouse was constructed on the steel base to isolate Biosphere 2 from the atmosphere. The $150 million chamber was ready for business in 1991. 8 542-1448_Pop_Eco_pgs_1-70.indd 8 7/7/08 2:52:29 PM Four men and four women were identied as the rst team. But before they closed the door, they had to populate Biosphere 2 with other organisms in order to turn the newly nished building into an ecosystem. The ecologists working on the project spent a long time selecting organisms. They knew that they needed plants, animals, and microorganisms. They needed to have food for eight people and life support for the organisms that would provide the food. They needed organisms to refresh the air and dispose of waste materials. The planning was complex and detailed—lives depended on getting it right. The First Mission In September 1991 the door was closed and sealed with the eight Biospherians and 1800 other populations on the inside. The challenge faced by the humans was the same one astronauts will probably face during our rst visits to other planets. The trip to the Moon takes a few days. A trip to Mars might take a year. The most efcient way to make such a journey would be in a miniecosystem, where everything needed for life recycles. Biosphere 2 had surprises for the scientists inside. Before long they noted that the oxygen concentration began to drop. The oxygen started at 21%, the concentration of oxygen in Earth’s atmosphere, but got down to 14%. This was a dangerous level for the people. Where was the oxygen going? Analysis revealed that the soil in Biosphere 2 was too rich in organic matter. The populations of microbes were growing out of control, using too much of the oxygen. The scientists reasoned that if the oxygen concentration was going down, the carbon dioxide (CO2) concentration should be going up. But the concentration of CO2 was not going up as fast as the scientists calculated. It was later discovered that the CO2 was being taken up by the massive amount of concrete that was still curing. On the biotic side, a problem came up with ants. An uninvited species, known as crazy ants, got into Biosphere 2 somehow and caused disruptions in the community. Not only did the ants put pressure on other organisms in the ecosystem, they clogged vents and chewed on wiring, creating quite a nuisance. How could tiny organisms like ants cause a major problem in the Biosphere 2? Crazy ants form “super colonies.” Super colonies have many queens and many nests. All of the ants work together to search for food, share food, and distribute resources. Most other species of ants form colonies with a single queen in a single nest and are highly territorial toward other colonies of the same species of ant. Crazy ant colonies, on the other hand, cooperate with one another. This gave them an advantage over other species of ants in Biosphere 2. While crazy ants are not aggressive to others of their species, they are very aggressive in searching out and attacking prey. They can effectively communicate the exact location of the prey to other ants in the super colony. Then they can launch an attack that will overwhelm even a large insect such as a cockroach. Crazy ants, like other ants and many other animals, communicate with each other by using pheromones. Pheromones are scent chemicals that send signals to other animals of the same kind. For example, ants leave pheromones on the ground to mark a trail for other ants in the colony to follow. While most other ants are thought to have only one trail pheromone, crazy ants have at least three different ones. Some of these pheromones evaporate faster than others, so they stay on the trail for only 2–3 minutes, while other pheromones may last for 24 hours. Crazy ants, with more than one pheromone, can provide more information to other ants so the colonies can adjust 9 542-1448_Pop_Eco_pgs_1-70.indd 9 7/7/08 2:52:30 PM quickly to changing conditions. The superior communications and the super colony cooperation seem to be the characteristics that gave the crazy ants the advantage over the other insect species in Biosphere 2 and allowed the crazy ants to displace most of the other arthropods. The Biospherians made it through the 2-year mission, but just barely, and not without a little assistance. The oxygen problem could be solved only by pumping in extra from outside. A second mission in 1994 lasted 6 months. Following the second mission, a decision was made. Biosphere 2 would no longer be a live-in facility, but would be transformed into a unique ecological research center. In 1996 Columbia University took over management of Biosphere 2 and continues to oversee the important international research going on there. The Current Research It is fairly easy to do an experiment with the plants and animals in your terrarium or aquarium. You could add some CO2 to one terrarium but not the other, to see if it made plants grow faster or slower. You could increase the temperature of an aquarium and monitor the health of the sh. But would your experimental results tell you what would happen in the rain forest or the ocean? How do you study an entire ecosystem? A real ecosystem is much larger and more complex than the ones you can build in class. To try to answer some of these questions, you could add CO2 gas to a eld or forest to see how plant growth might change, but the wind would soon blow the CO2 away. You could study the weather over a coral reef for a period of 40 or 50 years to see if there are any patterns, but it would be impossible to control variables. You might notice a difference in plant growth and health when you compare a wet, cold, rainy year to a hot, dry, sunny year. Is the difference because of the rain, the moisture in the air, the temperature, or the amount of sunlight? It is impossible to say with so many variables changing at once. What you really need is a box like your terrarium or aquarium that is big enough to hold a whole ecosystem. Then you could do experiments and control all the variables except the one you are studying. Where can you nd such a box? Biosphere 2. Biosphere 2 covers almost as much area as four football elds. Inside are seven different environments: rain forest, desert, tropical ocean, marsh, savanna, thorn scrub, and agroforest. One area of intensive study is the tropical rain forest ecosystem. Tropical rain forests can soak up CO2, a greenhouse gas that contributes to global warming. Tropical rain forests are sometimes called the lungs of the planet because they take in so much CO2 and produce so much oxygen during photosynthesis. Dense vegetation and long days of direct sunlight year-round enable rain forest plants to carry out photosynthesis at a higher rate than anywhere else on Earth. Some scientists think rain forests have great potential for controlling the rising CO2 level. Another possibility is that more CO2 in the atmosphere will result in rising global temperatures all over Earth. Warmer temperatures could result in less rain, because less water vapor will cool enough to condense into raindrops. Water and CO2 are both needed for photosynthesis to take place. If there is less rain, photosynthesis slows down, which means less CO2 will be removed from the atmosphere. Increased CO2 heats the atmosphere even more, reducing rainfall even further. Over time this can cause the average global temperature to rise, which can have a signicant effect on many ecosystems. 10 542-1448_Pop_Eco_pgs_1-70.indd 10 7/7/08 2:52:30 PM Biosphere 2 hope to answer these and many other questions about how the rain forest ecosystem responds to change. Coral reefs have been called the rain forests of the sea because there is so much diversity of life in coral reef ecosystems. Coral denes the ecosystem. Algae, sh, crabs, and many other kinds of sea organisms live on, in, and around the coral structures. Microscopic phytoplankton (single-celled algae and photosynthetic bacteria) are essential to the health of ocean ecosystems. Phytoplankton, which conduct photosynthesis, are food for coral and other small animals, which in turn are food for larger sea animals. Phytoplankton are the base of marine food chains just like green plants are the base of terrestrial food chains. John Adams, senior research specialist, ascends a canopy access system inside the Biosphere 2 Tropical Rain Forest to check leaves sealed in a branch bag. Inside the rain forest environment in Biosphere 2 scientists are doing experiments to determine how drier conditions affect the amount of CO2 taken up by rain forest plants. They can control the amount of “rainfall” with the overhead sprinkler system. CO2 can be pumped in. The temperature can be regulated with huge heating and cooling units. Scientists can change any of these variables one at a time to see what effect each has on the amount of CO2 taken up by the plants. What will happen if the CO2 level and the global temperature continue to rise? Will the rain forests take up more CO2? Will the rain forests take up less CO2? How will warmer temperatures or more CO2 affect the health of the plants? Scientists at Marine biologists report that there are fewer and fewer sh and other organisms living in the coral reef ecosystems around the world and that the growth rate of coral has slowed. During the winter of 1997–1998, one-tenth of the world’s coral reefs died. The temperature of the water in the affected areas that winter was 2–3°C above normal, making it one of the warmest periods on record. But was it temperature alone that killed the coral, or was it more complicated than that? Several scientists are studying the coral reefs in the ocean biome at Biosphere 2. The Biosphere 2 “ocean” holds 2,500,000 liters of water. The depth ranges from 0 meters (m) at the beach to 7 m in the deepest part. Scientists have investigated several factors they think might affect the health and survival of the coral. When they varied the concentration of CO2 dissolved in the water, the health of the corals declined. They found that excess CO2 dissolved in the water prevented coral from getting calcium out of the water to build their skeleton. 11 542-1448_Pop_Eco_pgs_1-70.indd 11 7/7/08 2:52:30 PM The studies of the coral reefs in Biosphere 2 provide evidence that the changes taking place in the ocean environment such as more dissolved CO2 affect the coral reef ecosystem in negative ways. As scientists learn more about ecosystems, two things become very clear. The rst is that any change in one part of an ecosystem affects every other part of the ecosystem, many times in ways that no one could have anticipated. The second is that the more we learn, the more we realize how complex natural ecosystems are and how little we understand about the way they work or what effect human activity has on them. Why should we care? What difference does it make if rain forests or coral reef organisms are disappearing? That’s not where we live. Well, it is where we live. Our planet is small. The atmosphere surrounds the planet and the seas wash up on all the continents. Changes in one ecosystem are communicated to the rest of the world by owing air and water. Everything is connected. Small changes in global temperature can have a huge effect on weather patterns. And weather distributes water, and water is life. Maybe you can join the small community of people trying to answer some of these tough ecosystem questions. College students from several universities across the country attend classes at Biosphere 2 for a semester to study environmental problems. There is also a summer program for high school students who are interested in studying environmental issues. Maybe in a few years... More information about these programs is available on the Biosphere 2 website at www.bio2.edu. The Planetary Spheres One way scientists think about Earth is as a set of nested, interacting Scientists gather at Biosphere 2 to conduct rain experiments at the laboratory’s ocean biome. spheres. The lithosphere Six inches of fresh water fell into the saltwater ocean over a 2-hour period to measure the effect a is the rocky, mineral part freshwater addition would have on the exchange of carbon dioxide into and out of the ocean. The of the planet that extends rain and air-water gas exchange experiment was funded, in part, by a grant from the David and from the solid surface into Lucile Packard Foundation. the mantle. This is the hard part of the planet that provides a sense of solidity and stability... most of the time. Periodically, we get reminders in the form of earthquakes and volcanic eruptions that the solid Earth is actually restless and dynamic. Wrapped around Earth is the atmosphere, the thin layer of gases that extends, for all practical purposes, no more than 600 kilometers above the surface. The atmosphere is a source of essential 12 542-1448_Pop_Eco_pgs_1-70.indd 12 7/7/08 2:52:30 PM gaseous chemicals, an energy-transfer system, a shield protecting us from extraterrestrial radiation, and an insulator. It is also an important medium for water distribution. sum total of all the living organisms on Earth is the biosphere. It is this raggletaggle, at times improbable, assemblage of millions of different kinds of life-forms that gives Earth its particular avor. Earth is a water planet. Because of the temperature on Earth, water exists naturally in three states: liquid, gas, and solid. All the water on Earth makes up the hydrosphere. The hydrosphere includes the oceans, lakes, rivers, streams, and aquifers. It includes the polar icecaps, glaciers, snowpacks, and permafrost. It also includes the aerial water vapor and condensates in the form of clouds, fog, and precipitation. All four spheres can be bundled into one global sphere called the ecosphere. The ecosphere is that portion of a planet that is inhabited by life. Thus, it includes a portion of the atmosphere, a portion of the lithosphere, a portion of the hydrosphere, and all of the biosphere. We focus on the biosphere in this course. However, we will continually consider the interactions between living organisms and the other three spheres to reinforce the idea that life is And nally, creeping, hiding, running, never disconnected from the physical burrowing, ying, slithering, and swimming environment. through, over, under, onto, and into the other three spheres is the biosphere. The T H I N K Q U E S T I O N S 1. Give at least two examples of how a change in one variable in an ecosystem can start a chain reaction that affects several other variables. 2. Why is global warming considered by some scientists to be such an important problem? 3. What are some advantages of doing research on ecosystems in Biosphere 2 rather than in the natural ecosystem? What are some disadvantages? 4. Think about the statement "Every decision has an environmental impact." What decisions do you make that add carbon dioxide to the environment? What decisions do you make that would add less carbon dioxide to the environment than you currently add? 5. Why should we be concerned about species becoming extinct? What endangered species are found in the area where you live? What has caused them to become endangered? What is being done to help them survive? 13 542-1448_Pop_Eco_pgs_1-70.indd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imiting Factors Nothing lives forever. Even the ancient bristlecone pine trees of the high mountains of the western United States die after a few thousand years. Most organisms live much shorter lives. Many insects live a few months; sh and small mammals a few years; many plants, reptiles, birds, and large mammals a few decades; and a scattering of others, like trees, a few centuries. Life is a temporary thing...for the individual. If a species is to continue to exist on Earth, the species must produce new individuals continually. Producing new individuals to maintain a population is reproduction, and every species has a way of reproducing. The rate at which a species can increase its population is its reproductive potential. Some species, like elephants, have modest reproductive potential. A female elephant reproduces a single offspring every 4 years. A single female Atlantic cod, on the other hand, can lay 10 million eggs a year. Clearly the potential for the cod to increase its population is much greater than the potential for the elephant to increase its population. So why don’t populations spiral out of control? Why aren’t there billions of billions of trillions of Atlantic cod lling all the oceans from top to bottom after 5 or 10 years? Because there are limiting factors imposed on every population on Earth. Limiting factors control the sizes of populations. BIOTIC LIMITS: PREDATION One way that populations are limited is through predation. Every organism is desirable to some other organism as a source of food. As we know, food provides the energy that is essential for survival. Therefore, if a species reproduces a lot of biomass, it will attract predators to take advantage of the energy source. We see this kind of population control in Mono Lake when the brine shrimp feed on the planktonic algae, reducing their numbers, and in turn the brine shrimp are eaten by phalaropes and gulls, reducing the population of shrimp. Predation can occur at any stage in the life cycle of an organism, including eggs and seeds, young, mature, and old. Populations are limited by removal of individuals as they are eaten. Diseases limit populations in the same way. Even though we don’t usually think of a large animal or plant being attacked by a microscopic bacterium, the result can be the same. A mountain lion capturing a deer, or a hawk taking a squirrel, removes an individual organism from the population. A disease organism can enter a population and kill many organisms, which also limits the size of the population. BIOTIC LIMITS: RESOURCES Populations are limited by food supply. If an organism cannot acquire the energy needed to survive and reproduce, the population will decline and, with it, the potential for producing the next generation. If a snake cannot nd enough mice to 22 542-1448_Pop_Eco_pgs_1-70.indd 22 7/7/08 2:52:38 PM sustain itself, it will starve to death. Even if it survives, it may be so weak that it can’t reproduce. Similarly, if there is a poor crop of acorns, squirrels may starve. Even if they survive, they may not be able to feed their young. In 1982 a reduced population of brine shrimp in Mono Lake prevented the California gulls from successfully feeding their chicks. Most of the gull offspring died that year. Lack of food is one of the most important limitations on populations. ABIOTIC LIMITS: REPRODUCTIVE ENVIRONMENTS Many organisms require specic conditions in order to reproduce. If the number of locations where reproduction can occur or their quality is limited, reproduction will be limited. Bank swallows need sandy cliffs in which to dig nesting burrows. If a sandy cliff tumbles down during a ood or earthquake, suitable nesting sites are lost. Salmon need clean gravel streambeds in which to lay their eggs, and black bears need winter dens in which to give birth. Without an environment that provides for the physical conditions needed to reproduce, young will not be born. Lack of access to required reproductive environments for a species limits populations. ABIOTIC LIMITS: SEASONS Seasonal changes put pressure on populations. In the temperate and polar latitudes, winter is a major factor in population limitation. During winter, days are shorter, so primary production by photosynthetic organisms slows or, in the case of deciduous trees, stops entirely. Often winter brings rain, snow, and wind, each of which adds stress to populations. Some animals respond to the threat of wind, ood, and freezing by leaving the area. Birds, because of their mobility, are famous for migrating to warm regions. Others, like the American bison and caribou, go on long treks to nd greener winter environments. Some organisms become dormant, basically shutting down until spring. Frogs, sh, bears, squirrels, snakes, maple trees, and hosts of other organisms use dormancy, reduced activity, and winter sleep to wait out the winter. These strategies work if a number of conditions have been met. • The wintering place offers sufcient protection. • The organism has accumulated enough fat or has stored enough food to survive the winter. Winter is the main limiting factor for many temperate and polar populations. Many populations decline to minimal levels, like the brine shrimp in Mono Lake, and then expand rapidly in the spring. Seasonal uctuations in population size such as those at Mono Lake are normal and healthy. CARRYING CAPACITY When you stand back and take the large view of life on Earth, you realize it is a struggle to survive there. Every living thing has fundamental requirements for life, and if it doesn’t get those things, it dies. One of the most critical requirements is energy. Energy enters the ecosystem as sunlight. Photosynthetic organisms capture the energy and transform it into carbohydrates, like sugar, that we call food. The energy is in the chemical bonds. The amount of food 23 542-1448_Pop_Eco_pgs_1-70.indd 23 7/7/08 2:52:39 PM that can be produced is limited by several factors, including access to light, space for living, and availability of resources such as water, carbon dioxide, and minerals. For any given ecosystem there is a limit to the amount of food that the producers can make. We know that the other populations in an ecosystem acquire energy by eating each other. Primary consumers eat producers, secondary consumers eat primary consumers, and so on. The number of consumers is limited by the amount of production. The total number of individuals of a population that can be sustained indenitely by an ecosystem is the carrying capacity for that species. For instance, a backyard ecosystem might support three rabbits year after year on the amount of grass and other vegetation growing there. The carrying capacity for rabbits is three. If six rabbits move in, the carrying capacity of the ecosystem is exceeded. As a consequence, in order to survive, the rabbits will eat so much of the vegetation that they will damage the ability of the producers to produce in the future. Exceeding the carrying capacity of an ecosystem always produces changes that will alter the nature of the ecosystem. population would die off. In healthy ecosystems there are always survivors of every kind in sufcient numbers to reproduce and keep the population going. Usually the primary producers establish the overall carrying capacity of an ecosystem. How much food energy is produced by the photosynthesizers that can be consumed and distributed throughout the food web of the ecosystem? When you know the answer to that question, you are closer to knowing the carrying capacity of the ecosystem. Mono Lake is an ecosystem with a tremendous carrying capacity for its size. Mono Lake has plenty of light, water, carbon dioxide, and minerals. The algae reproduce rapidly. The limiting factor for Mono Lake algae is one element—nitrogen. Even so, the biomass of algae produced in the lake supports trillions of brine shrimp and brine ies. These in turn nourish millions of birds and a few coyotes. A lot of life ows through Mono Lake each year. Contrast this with a grassland on the Great Plains. Grasses grow more slowly, thus taking longer to regenerate their biomass. The amount of grazing by insects, rodents, deer, and cattle must not exceed the capacity of the grasses to regenerate. The carrying capacity of the grassland is less than the carrying capacity of Mono Lake. In an ecosystem the consumers never eat all the organisms they prey upon. Squirrels never eat all the acorns, caterpillars never eat all the oak leaves, mountain sheep never eat all the grass, sharks never eat all the seals, and so on. This is very important because if they did, the prey species would be gone. The predators’ offspring would have nothing to eat, and the predator 24 542-1448_Pop_Eco_pgs_1-70.indd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t io n o Par tic le s in M Air is matter. It has mass and occupies space. Air is a mixture of many gases. Air is approximately four-fths nitrogen and one-fth oxygen. All the other gases, including carbon dioxide and water vapor, make up only a little more than 1% of the mass of a sample of air. same number of particles as every cubic centimeter of air outside the bottle. Air is matter in its gas phase. That means that the nitrogen and oxygen particles in air are not connected to other particles. Gas particles y through space as individuals. Air particles fly through space as individual particles. Air particles fill an open bottle. It is important to remember that air particles are really millions of times smaller than the representations in the illustrations. A cubic centimeter of air actually has about one quintillion air particles! A quintillion is a one followed by 18 zeroes (1,000,000,000,000,000,000). The illustrations are therefore not accurate, but they are good for thinking about what is going on at the particle level. After you drink a bottle of spring water, you have an excellent container for an air investigation. The empty bottle, of course, isn’t empty. It is full of air. Because air particles are ying all around, they are going into and out of the open bottle all the time. The density of air in the bottle is exactly the same as the density of the air outside the bottle. That means that every cubic centimeter of air in the bottle has the 23 542-1505_Chem Inter_TEXT.indd 23 4/30/08 12:17:08 PM Particles Have Kinetic Energy Not only are air particles incredibly small, they are always moving. And they move fast. At room temperature, they are going about 300 meters per second. That’s equal to about 670 miles per hour. Back to the air investigation. Stretch a balloon over the top of the bottle full of air. Now the air is trapped inside the bottleand-balloon system. No particles can get in or out. Moving objects have energy. It’s called kinetic energy. Anything that is in motion has kinetic energy, whether it is an ocean liner, a bicycle, a y, a snail, you walking to class, water falling down a waterfall, or an oxygen particle in the air. They all have kinetic energy. Kinetic energy, like all forms of energy, can do work. Air particles do work when they crash into things. Air particles push on each other, on you, on the walls of containers, and on everything else around them. Every air particle crashes into another particle about 10 billion times every second! The amount of kinetic energy an object has depends on two things: the mass of the object and the speed at which it is moving. You can’t change the mass of an air particle, but you can change its speed. By making a particle go faster, you increase its kinetic energy. Air particles can be made to move faster by heating a sample of air. Heat increases the kinetic energy of particles. A balloon can trap the air inside a bottle. The density of air particles is the same in the bottle, in the balloon, and in the air surrounding the bottle-and-balloon system. 24 542-1505_Chem Inter_TEXT.indd 24 4/30/08 12:17:08 PM Now place the bottle-and-balloon system in a cup of hot water. The hot water warms the air inside the bottle. Particles in the warm air start to move faster. After a few minutes, the bottle-and-balloon system looks like this. Why did the balloon inate? The hot water heated the air in the bottle. As a result, the air particles began moving faster. Faster-moving particles have more kinetic energy. Faster-moving particles hit each other harder, which pushes them farther apart. You can see in the illustration that the particles of warm air inside the bottle-and-balloon system are farther apart. The faster-moving particles also push on the balloon membrane harder. The particles push hard enough to stretch the balloon membrane. The increased kinetic energy of the particles pushes them farther apart (air expansion), and the membrane stretches to hold the increased volume of air. Hot water increases the kinetic energy of the air particles inside the bottle-and-balloon system. The particles fly faster and hit each other harder. The particles push farther apart, causing the gas to expand. 25 542-1505_Chem Inter_TEXT.indd 25 4/30/08 12:17:09 PM What Happens W hen Gases, Liquids, and Solids Heat Up? Gas. If a sample of matter is gas, its particles are not bonded (attached) to other particles. Each particle moves freely through space. When a sample of air The particles in gases fly through space in all directions as individuals. Liquid. Particles in liquids are in close contact with one another. Attractions between the particles keep them from ying freely through space. The particles in liquids can, however, move over, around, and past one another. Individual particles in liquids are able to move all through the mass of liquid. The particles in liquids are held close to each other. Particles bump and slide around and past each other. When liquids get hot, the particles bump and push each other more. Increased bumping pushes the particles farther apart. This causes the liquid to expand. When gases get hot, the particles fly faster. Faster particles hit other particles harder, pushing the particles farther apart. This causes the gas to expand. heats up, the particles move faster and hit each other harder. The result is that the particles push each other farther apart. In the illustrations above, a container of gas has a exible membrane across the top. When the gas gets warm, the kinetic energy of the particles increases, particles hit each other harder, and the gas expands. As the gas expands, it pushes the membrane upward. The motion of particles in a liquid is kinetic energy. When a liquid gets warm, the particles move faster. The particles have more kinetic energy. As a result, they hit other particles more often and hit harder. This pushes the particles farther apart. When particles are pushed farther apart, the liquid expands. 26 542-1505_Chem Inter_TEXT.indd 26 4/30/08 12:17:10 PM Summary Solid. Particles in solids have bonds holding them tightly together. The particles cannot move around at all. The particles are, however, still in motion. Particles in solids are always vibrating (moving back and forth) in place. General Rule 1. When a sample of solid, liquid, or gas matter heats up, it expands. When matter gets hot, its particles gain kinetic energy. The increased kinetic energy pushes the particles farther apart. This causes the matter to expand. General Rule 2. When a sample of solid, liquid, or gas matter cools down, it contracts. When matter cools down, its particles lose kinetic energy. The decreased kinetic energy lets the particles come closer together. This causes the matter to contract. The particles in solids are bonded. Particles move by vibrating, but do not change positions. Review Questions 1. What is kinetic energy? 2. What are two ways to increase an object’s kinetic energy? When solids get hot, the particles vibrate more. Increased vibration pushes the particles farther apart, causing the solid to expand. 3. Explain why a balloon inflates when a bottle-and-balloon system is placed in hot water. 4. What happens to a sample of matter when its particles lose kinetic energy? The vibrational motion of particles in solids is kinetic energy. Heat makes the particles in a solid vibrate faster, giving them more kinetic energy. Faster-vibrating particles bump into one another more often and hit each other harder. This pushes the particles farther apart. When particles are pushed farther apart, the solid expands. 5. How are particles in solids, liquids, and gases the same? How are they different? 27 542-1505_Chem Inter_TEXT.indd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lose Reading and Text Dependent Questions in Science The Crater That Ended The Reign Of the Dinosaurs (Planetary Science – Grade 8) The text selection, The Crater That Ended The Reign Of the Dinosaurs, is found in FOSS Student Resource Book, Planetary Science, pgs. 67-‐68. Look in the Student Learning Outcome Document for guidance on when this should be taught. http://bpscurriculumandinstruction.weebly.com/student-‐learning-‐outcomes-‐by-‐grade.html BPS Science Department • 1216 Dorchester Avenue • Dorchester, MA 02125 Phone (617) 635-‐8750 • Fax (617) 635-‐9801 © 2013 BPS Science Department The Crater That Ended The Reign Of the Dinosaurs (Planetary Science – Grade 8) Student Questions 1. Based on the text, paraphrase how sedimentary rocks are formed. 2. The article states that iridium is a rare element. Based on the text, what explanation is offered to explain the unusually high concentration found in the rocks that Dr. Alverez was studying? 3. What possible explanation did Alverez and his research group provide for the reason why they found “high concentrations of iridium in 65-‐million-‐year-‐old rocks” all over the planet? BPS Science Department • 1216 Dorchester Avenue • Dorchester, MA 02125 Phone (617) 635-‐8750 • Fax (617) 635-‐9801 © 2013 BPS Science Department 4. Based on the evidence in the text, what was the scientific model Alverez’s group worked up regarding what happened to the extinction of the dinosaurs? 5. What was one challenge to the model? 6. How did scientists address this challenge? What did they find? 7. What conclusions could the scientists reasonably draw, based on the presence of the Chicxulub Crater, for their model? BPS Science Department • 1216 Dorchester Avenue • Dorchester, MA 02125 Phone (617) 635-‐8750 • Fax (617) 635-‐9801 © 2013 BPS Science Department