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THE ECOSYSTEM: THE FIELD, THE PLAYERS, AND CHANGING VARIABLES

  1. Science seeks to understand how natural events occur. Many natural events can be studied and better understood when scientists use controlled experiments that can be repeated many times. Some natural events, such as earthquakes, cannot readily be studied with controlled experiments.

Part A- Explain why earthquakes are difficult to study with controlled experiments.

Part B- Describe how geologists could still study earthquakes and their effects without performing controlled experiments.

  1. According to the nitrogen cycle, how do animals receive the nitrogen they need?
  1. Through the absorption of nitrate ions after they are released into the air by plants
  2. Through the consumption of plants that have already taken in large amounts of nitrogen
  3. Through the consumption of dead matter containing nitrate ions and ammonium ions
  4. Through the consumption of living or dead organic matter that contains molecules composed partially of nitrogen
  1. Trophic levels show the flow of energy through an ecosystem. Which food chain shows the correct flow of energy through trophic levels?
  1. Grass  human snake  hawk
  2. Human  grass  grasshopper  toad  snake  hawk
  3. Grasshopper  weed  snake  human  bacteria of decay
  4. Grass  grasshopper  toad  snake  hawk  bacteria of decay
  1. The Gulf Stream Current carries warm water from the Caribbean Sea to the North Atlantic Ocean. The British Isles lie in the path of this current. How would you expect the climate of the British Isles to differ from the climate of other places that are similar latitudes but are not near the Gulf Stream Current?
  1. Temperatures will be colder in the British Isles.
  2. Ocean currents have little or no effect on climate.
  3. The British Isles will receive much less precipitation.
  4. The British Isles will experience milder temperatures.
  1. Seasonal climate differences are more extreme in some places that in others. Far to our north in Canada, for example, there is a much larger difference between summer temperatures and winter temperatures and winter temperatures than in Florida, which is closer to the equator. What are the causes of these seasonal climate differences, and why are they more extreme in some places?
  2. According to the nitrogen cycle, how do animals receive the nitrogen they need?
  1. Through the absorption of nitrate ions after they are released into the air by plants
  2. Through the consumption of plants that have already taken in large amounts of nitrogen
  3. Through the consumption of dead matter containing nitrate ions and ammonium ions
  4. Through the consumption of living or dead organic matter that contains molecules composed partially of nitrogen.
  1. Trophic levels show the flow of energy through an ecosystem. Which food chain shows the correct flow of energy through trophic levels?
  1. Grass  human snake hawk
  2. Human  grass  grasshopper  toad  snake  hawk
  3. Grasshopper  weed snake  human bacteria of decay
  4. Grassgrasshopper toad snake hawk bacteria of decay
  1. An area contains active volcanoes and experiences earthquakes. Which of the following statements about this area is most likely to be true?
  1. The area receives little or no rainfall or snow.
  2. The area is rich in fossils and other sedimentary rock.
  3. The area has a small seasonal temperature difference.
  4. The area is located very near a tectonic plate boundary.
  1. Along the western coast of South America, the oceanic Nazca Plate collides with continental South American Plate. As this collision occurs, they very dense Nazca Plate is forced beneath the less dense South American Plate.What type of tectonic boundary is this? Describe the geological features you might expect to see on the South American plate near this boundary.
  2. Draw a diagram depicting the relationship described: Worms are eaten by birds, which in turn are eaten by snakes. If all the birds in an area died due to a new disease, what would the impact be to the local populations of worms and snakes after one month? After one year? Explain your answer.
  3. The Coriolis force causes ocean currents and winds including hurricanes, to curve into spiral-shaped weather patterns. What causes the Coriolis effect?
  1. The rotation of Earth on its axis
  2. The movement of tectonic plates
  3. The uneven heating of Earth’s surface
  4. The revolution of Earth around the Sun
  1. Steven lives between the ocean and a large mountain range, with prevailing winds coming from the ocean. The weather where Steven lives if often rainy, and the area is rich in plant life. Steven’s cousin, Deborah, lives on the other side of the mountain range. Where Deborah lives it is a desert. Why does the area where Deborah lives receive so much less precipitation than the area where Steven lives?
  2. Over time, the periodic table has grown to at least 110 elements, most of which are named after researchers. What does this demonstrate about scientific understanding?
  1. It mostly grows through large teams of researchers.
  2. It always seeks to disprove previous scientific theories.
  3. It grows in time, through the work of many researches.
  1. The law of superposition states that younger layers of rock generally lie on top of older. Sample four in the graph below appears to violate this law, but actually does not. What does this tell us about scientific laws?
  1. They are only valid when under scientific control.
  2. If they seem wrong, you should rely on your own eyes.
  3. They often appear wrong due to unpredictable factors.
  4. They often appear wrong if they are not carefully interpreted.
  1. In Egypt, farmers grow large fields of crops in the area immediately surrounding the Nile River. However, in the very dry desert areas farther from the river, no crops are grown. Why do crops grow so abundantly near the river but not in the desert regions that are nearby?

THE ECOSYSTEM: THE FIELD, THE PLAYERS, AND CHANGING VARIABLES

Answer Key

  1. Part A, the difficulties: There are many variables in an earthquake; eg. how deep was the epicenter (where the action of the quake was centered)?; strength and duration, how to simulate the quake’s effects on nearby plates?; different surface features of the land above it, both artificial (man-made) and natural features; quality of building materials; different cultures use different building techniques.

Part B, studying effects of earthquakes: use computers to model earthquakes; model past quakes and input x-variables (independent variables) like strength and duration (time the earth was shaking) of the quake while noting effects (y-variable, the dependent) on the structures. Once have a working model, vary strength and duration in the computer model to predict the effects. This would only work for the area in which the data was gathered; each region would have to have its own model.

  1. (B) Nitrogen cycle: step one – nitrogen-fixing bacteria take N2 from the air and turn it into usable nitrogen for plants to absorb into their roots; step two –plants use the nitrogen to build molecules necessary for life; step three – plants are consumer by primary consumers (herbivores); step four – herbivores are eaten my secondary consumers; step five – animals die and are consumed and reduce by decomposers (monera, protista, fungi); step six – reduced to elements, some gases are released to the atmosphere and some are absorbed back into the soil as nutrients.
  2. (D) Trophic levels: sun  producers (plants)  primary consumers (herbivores)  secondary consumers (eat the herbivores)  tertiary consumers (eat the secondary consumers, top of the food chain)  decomposers (monera, protista, fungi; return element, molecules to the soil or atmosphere as nutrients or gases)
  3. (D) British Isles are affected by the warm Gulf Stream. This answer cannot be A because a warm current would lead to warmer temperatures. The answer cannot be B because ocean temperatures do have an effect on air temperatures. The answer cannot be C because when you have a warm water current, these waters would naturally have more energy to evaporate into the gas phase (water vapor) and with increased water vapor, you will have more precipitation, not less. The answer must be D because we know that water has higher specific heat.
  4. Comparing Canada to Florida

-Canada is large country with large inland region (inland = not on a coast) while Florida is a peninsula surrounded by water. This means that many air masses that form over Canada will not have water vapor. Air masses that form over water have lots of water vapor. Since water has a high specific heat (a material with high specific heat requires a lot of energy to change the temperature of the material), coastal regions have small temperature variations. In regions with dry air masses, like the ones that form over land, these experience huge temperature variations; eg. Florida temperature range in a July day = 77-91 ⁰F (ΔT = 14⁰F); Las Vegas, Nevada (desert) temperature range in a July day = 78-104⁰F (ΔT = 26⁰F).

-Canada is more northern than Florida, Florida is closer to the equator. At the equator, sun light is received directly, at an angle of 90⁰; whereas Canada, because of earth’s tilt, receives sunlight at an angle less than 90⁰.

  1. Duplicate of No. 2
  2. Duplicate of No. 7
  3. (D) Volcanoes and Earthquakes are the result of plate tectonics. Volcanoes are a feature of convergent boundaries, especially oceanic converging on a continental crust. As the oceanic crust (more dense than convergent) subducts in the subduction zone, it melts in the asthenosphere. This action of subducting can result in an earthquake, but also, transform boundaries, as they scrape past each other, result in earthquakes. This region is on plate boundaries.
  4. The Nazca Plate is more dense so it subducts under the South American plate at a convergent boundary. The Nazca is oceanic, the South American in continental. Oceanic crust is more dense than continental crust. Around these boundaries, one would expect mountains and rains on the side facing the ocean, with drier regions behind it due to the rain shadow. Additionally, volcanoes are a result of these types of boundaries.
  5. Worms  birds  snakes; if all the birds died, in one month, the worm population and the snake population would increase dramatically; after one year, the snake population would die off from starvation, and the worm population would reach a plateau of population maximum, with no natural predators.
  6. (A) The Coriolis force is the result of the Earth spinning on its axis.
  7. This is a perfect example of a rain shadow; see below. Remember also, as you climb in elevation, temperature decreases by 0.7°C for every 100 m you climb.

  1. (C) Scientific knowledge requires the work of many scientists around the world and over long periods of time with great effort. Scientists share their knowledge with each other to better all humankind. The answer is C.
  2. (D) This problem was tricky because the picture is not shown, but you do not need the picture. It is common sense, sometimes, you might look at something and say, “The law says this, but this doesn’t match the law, so the law must be wrong.” A law is a law because it answers all related problems all of the time under all circumstances specified. More than likely, you are not interpreting what you are seeing accurately.
  3. The River Nile floods every year, depositing nutrient-rich sediment all over the river valley. When the waters cede (or lower back down to the normal level of the river), the sediments are left behind. This sediment is perfect for planting and raising crops. The desert doesn’t receive the benefit of this yearly soil deposition from the river, and is dry, so therefore, will not take to growing crops.

Aventura Waterways K-8 Center Gisela Dumm FCAT Science Camp 2010-2011