Archive | March, 2011

Gizmo: Greenhouse Effect

30 Mar

Gizmo Warm-up

Like the windows of a car, greenhouse gases play a major role in regulating Earth’s climate. Withoutthe gases that trap heat in Earth’s atmosphere, Earth would be a frigid desert like Mars (average temperature -55°C, or -67°F). Too much greenhouse gas and Earth could be a fiery inferno like Venus (average temperature 450°C, or 850°F).

On the Greenhouse Effect Gizmo™, set the Greenhouse gases to 0% and the Simulation speed to fast.

1. Click Play ( ) and view the BAR CHART tab. The temperature will go up and down every day, but try to look at the overall trend. What happens to the temperature over time?

2. Now set the Greenhouse gases to 100% and let the simulation run for a while. How does a maximum amount of greenhouse gas affect the temperature?

Activity:  Heat in, heat out Get the Gizmo ready:

•Click Reset ( ).

• Set Simulation speed to slow. • Be sure the Greenhouse gases level is 10%. Question: How do greenhouse gases affect Earth’s climate?

1. Observe: Select the BAR CHART tab and click Play. After about 24 simulated hours, click Pause ( ). What do you notice about the heat flow into and out of Earth’s atmosphere?

. Analyze: Select the TABLE tab.

A. At what time of day is heat flow into the atmosphere (Hin) greatest?

B. At what time of day is heat flow into the atmosphere (Hin) least?

C. Does heat flow out of the atmosphere (Hout) change during a day?

D. At what time of day is surface temperature highest?

Lowest?

3. Predict: Click Reset. When you change the amounts of greenhouse gases in the atmosphere, which factor(s) do you expect to change? (Choose your answer/answers.)

Heat flow in Heat flow out  Temperature

4. Experiment: Select the BAR CHART tab, and click Play. While the simulation is playing, move the Greenhouse gases slider back and forth.What do you notice?

5. Experiment: Click Play, and this time observe the GRAPH tab as you change the Greenhouse gases. What do you notice?

6. Draw conclusions: The influence of greenhouse gases on temperature is called the greenhouse effect. Based on what you have seen, how do greenhouse gases affect the heat flow into and out of Earth’s atmosphere?

7. Extend your thinking: Atmospheric concentrations of greenhouse gases such as carbon dioxide have risen dramatically in the past century. Most scientists agree that this has begun to result in global warming, a slow increase in average temperature worldwide.  What are the possible consequences of global warming?

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Directions for Gizmo Assignments

30 Mar

Below is a step-by-step set of directions for making sure you complete Gizmo assignments correctly:

1. Open http://www.explorelearning.com

2. In a separate window, open pmcsscience3.wordpress.com

3. Login to the Gizmo with u: secondp112 and p: cow864

4. Open specific Gizmo

5. Highlight questions on pmcsscience [if your right-click doesn’t work, hold down CTRL+C]

6. Click on the “Comments” button

7. After the new page opens, go all the way to the bottom of the page, and click “Paste” or CTRL+V

8. After reading each question, go back into the gizmo to obtain the right data, then type your answer in the space.

9. At the very end, make sure to click on “Post Comment”

10. That’s it!

Gizmo: Pond Ecosystem

28 Mar

The Pond Ecosystem Gizmo™ lets you study ponds as an ecologist would. Each of the tools can be dragged to the pond to take measurements.

1. Drag the Thermometer to the pond at 6:00 AM. What is the water temperature? _______ °C

2. Click Fast-forward ( ) until about 12:00 PM, and then click Pause ( ).What is the water temperature now? _______ °

C3. Just as soda contains dissolved carbon dioxide, pond water contains dissolved oxygen. The unit for measuring the concentration (amount) of oxygen is parts per million (ppm).Drag the Oxygen gauge to the pond. What is the concentration of oxygen? _____________

4. Click Play ( ) and drag the Fishing pole to the pond. Fish for about four hours.How many catfish did you catch? _____________ How many trout? _____________

Introduction: The fish in a pond are affected by biotic factors such as other fish, aquatic plants, insects, and bacteria. They are also affected by abiotic factors, or nonliving things such as temperature and the concentration of dissolved oxygen.

Question: How does the amount of dissolved oxygen in a pond change during one day?

1. Observe: Use the Oxygen gauge to measure the concentration of dissolved oxygen at several different times. How does the oxygen concentration change over a single day?
2. Predict: At what time should the amount of oxygen in a pond be lowest? (Choose one) 6:00 AM 12:00 PM (noon) 6:00 PM 12:00 AM (midnight)

3. Test: Measure the dissolved oxygen at four times during the day: 6 AM, 12 PM (noon), 6 PM, and 12 AM (midnight). Then click New pond and repeat the test for two more ponds. Record your results in the table below.

4. Analyze: Was your prediction correct for all three ponds? Explain.

5. Draw conclusions: The dissolved oxygen in a pond is produced by pond plants and algae in a process called photosynthesis.

A. At what time of day does photosynthesis take place?

B. What source of energy is present during this time?

C. Why does the level of dissolved oxygen go down after sunset?

Activity B

1. Explore: To investigate the question, measure the oxygen concentration and go fishing in several ponds. (To fish, click Play and drag the fishing pole into the pond for several hours.

2. Form hypothesis: How does oxygen concentration affect the fish that live in a pond?

3. Predict: If you fish in four ponds, will more fish be caught in the two ponds with the lowest oxygen concentrations, or the two ponds with the highest oxygen concentrations? Explain.

4. Test: Investigate four ponds. For each pond, measure the dissolved oxygen concentration at 6:00 AM. Fish for six hours and record how many catfish and trout you catch in each pond.(Hint: To find a pond with relatively high levels of dissolved oxygen, click No farms.)

5. Analyze: What does your data show?

6. Draw conclusions: Which type of fish can survive better in low-oxygen conditions? Explain.

Gizmo: Food Chain [Advanced, Activity B]

21 Mar

Before starting the Gizmo “Food Chain,” briefly review the following vocabulary words:

Vocabulary •

Consumer – an organism that obtains energy by feeding on organic matter.

o Organic materials are carbon-based compounds produced by living things.

o All animals, all fungi, and even some plants are consumers.

o A cow chewing grass, a person eating a steak, earthworms digesting manure, and mold growing on bread all represent consumers in action. In each case the organism is consuming organic matter.

• Ecosystem – a community of living things along with their natural environment.

• Equilibrium – a stable situation in which opposing forces are balanced. o If an ecosystem is in equilibrium, the population of each organism will not change much from year to year.

• Food chain – a sequence of organisms in which each organism feeds on the one below.

o Example: Grass  Rabbit  Snake  Hawk. In this food chain, rabbits eat grass, snakes eat rabbits, and hawks eat snakes.

• Population – all organisms of a certain kind within a defined region.

• Predator – an animal that kills and eats other animals.

• Prey – an animal that is killed and eaten by other animals.

• Producer – an organism that converts simple inorganic matter (such as water and carbon dioxide) into organic matter (such as sugar and protein).

o Most plants use the energy of the Sun to create organic matter from carbon dioxide and water. This process is called photosynthesis.

o No sunlight reaches the ocean floor, but some bacteria can use energy from hot water vents on the ocean floor to produce organic material. These producers support entire ecosystems deep below the ocean surface.

——————————————–

Open the following http://www.explorelearning.com , logging in with secondp112 and cow864

[Copy the questions below into the comments area, answering as many questions as possible]

Gizmo Warm-up

The SIMULATION pane of the Gizmo shows the current population, or number, of each organism in the food chain.

1. What are the current populations of each organism?

Hawks: _____

Snakes: _____

Rabbits: _____

Grass: _____

2. Select the BAR CHART tab, and click Play ( ). What do you notice about each population as time goes by?  If populations don’t change very much over time, the ecosystem is in equilibrium.

3. Compare the equilibrium populations of the four organisms. Why do you think populations decrease at higher levels of the food chain?

ACTIVITY B

Get the Gizmo ready:  • Click Reset. • Select the GRAPH tab

Question: An ecosystem is a group of living things and their physical environment. How do ecosystems react to major disturbances?

1. Observe: Kill off most of the hawks using the – button, and then click Play. Observe the GRAPH for about 12 months, and then click Pause. What happens?

Analyze: Explain why you think the population of each organism changed the way it did. (Use extra paper if necessary.).

Experiment: Click Reset. Try making other changes to the ecosystem. Use the + or –buttons, or choose Diseased from the dropdown lists. Click Play and observe for at least 12 months. Record what happens BELOW.

4. Summarize: Give at least one example of each of the following: A. A major disturbance that the ecosystem was able to recover completely from.

. A major disturbance that caused the ecosystem to stabilize at a new equilibrium.

. A major disturbance that caused the ecosystem to completely collapse.

. (Challenge) A major disturbance that almost caused a total collapse, but that the ecosystem was able to recover from eventually.

Gizmo: Rainfall & Bird Beaks

7 Mar

Gizmo Warm-up

Darwin’s finches are one of many types of animals on the Galápagos Islands that have unique adaptations, or traits that help an organism survive in its environment. The Rainfall and Bird Beaks Gizmo™ allows you to explore how rainfall influences the range of beak shapes found in a single finch species.

1. The beak depth of a finch is the distance from the top of the beak to the bottom, as shown.

A. What is the current average beak depth in the Gizmo?

B. Select the BAR CHART tab. Do all the finches have the same beak depth?

2. Click Play ( ) and let the simulation play for five years with average rainfall (5 inches/yr). Select the GRAPH tab and view the Finches vs time and Beak depth vs time graphs.

A. How does the finch population change?

B. Does the beak depth change significantly?

Activity A:  Normal years

Get the Gizmo ready:  • Click Reset ( ). Introduction: The Galápagos Islands are very dry, with an average rainfall on some islands of only five inches per year. The amount of rainfall has a large impact on the abundance and types of seeds that are available to be eaten by finches. In the process of natural selection, only the finches that are best adapted to the available seed types survive and have offspring.

Question: How is the finch population affected by a period of average rainfall?

1. Observe: With the Rain sliders set to 5 inches, click Play, and then Pause ( ) after one year has passed. Select the TABLE tab and look at the Month and Finches columns.

A. How did the finch population change over the course of one year?

The finches have their young during the rainy season. Based on the table, which part of the year do you think is the rainy season?

2. Analyze: Click Reset, and choose the BAR CHART. The bars represent the numbers of finches that have different beak depths. The range of beak depths is equal to the difference between the largest and smallest beaks.

A. What is the average beak depth of the current finch population?

B. What is the range in beak depths in the population?

C. Do most of the finches have beak depths near the lower extreme, the middle, or the higher extreme of the range?

3. Experiment: Click Play, and observe the bar chart as the simulation plays for five years. A. What is the average beak depth now?

B. What is the current range of beak depths?

C. Based on what you have seen, are finches with very small, medium, or very large beaks most likely to survive in times of normal rainfall? Justify your answer.

B:  Drought Get the Gizmo ready:  • Click Reset.

Introduction: In years of extreme drought, Galápagos plants don’t produce new seeds. The small, delicate seeds get eaten up quickly, leaving behind only the largest, toughest seeds. Question: How does drought affect the finch population and average beak depth?

1. Form hypothesis: What type of beak do you think will be best for finding food in a drought?   .

Predict: Select the BAR CHART tab. On the left side below, sketch the current bar chart and list the average beak depth and range of beak depths. On the right side, sketch what you think the chart will look like after five years of drought. Explain your predicted graph.

Initial beak depths         Beak depths after 5 years (predicted) Initial number of finches:

Explanation:

Initial average depth:

Initial range of beak depths:

3. Experiment: Use the sliders to set the Rain to one inch for each of the five years in the simulation. Click Play, and wait for five years. Observe the beak of the finch.

A. How does the beak depth change over time?

B. What is the final average beak depth?

C. What is the final range of beak depths?

4. Describe: Compare the final bar chart to the initial bar chart. How have the finches been affected by drought? Describe at least two changes that you notice.  .

Analyze: Was the increase in the average beak depth caused by an increase in largebeaked finches or a decline in small-beaked finches? Explain your answer.

. Draw conclusions: What do you think caused the changes in the finch population and average beak size during the drought?

. Interpret: Directional selection occurs when individuals at one end of a range are more likely to survive than intermediate individuals or individuals at the opposite end of the range. Stabilizing selection occurs when intermediate individuals are the most likely to survive. Is directional selection, stabilizing selection, or both operating in this example? Explain.

8. Think and discuss: Evolution is the process by which populations of organisms can change over time. How is directional selection related to evolution?

Evolution: Artificial & Natural Selection

2 Mar

Gizmo Warm-upDog breeds and other varieties of domesticated animals were developed through artificial selection. Over many generations, breeders selected which animals to mate in order to select for desired traits. The Evolution: Natural and Artificial Selection Gizmo allows you to try your hand at breeding insects with a variety of colors. To begin, select the Artificial selection option.1. Drag the 10 insects into the breeding alcoves on the left side of the Gizmo.

A. How many breeding pairs are there? ____________________

B. How many offspring are produced? ____________________

2. Circled insects have mutations, or changes to their DNA.

How many of the offspring insects in this generation have mutations? ____________________

Activity A: Genotype and phenotypeGet the Gizmo ready:Select Natural selection.Question: How are genes inherited and modified over many generations?

1. Observe: The fitness of an insect is a measure of how well it is adapted to its environment.

A. What is the initial Average fitness of these insects? _________________________

B. Click Play ( ), and observe the simulation for several generations. What occurs in each generation? ___________________________________________________________________________________________________________________________________________________________________________________________C. Increase the Sim. speed by one level. Click Pause ( ) after 30 generations. Whatis the Average fitness now? ____________________________________________

2. Analyze: Set the Sim. speed to its slowest level. Click Play, and then Pause when the offspring appear. Choose a pair of parents in which both parents have a different color.

A. Move your cursor over a parent insect. The genes that control color make up an insect’s genotype, while its actual color is its phenotype. Fill in the genotypes and phenotypes of each parent below.Parent 1 Parent 1        Parent 2 Parent 2genotype phenotype genotype phenotypered = _______ red = _______green = _______ green = _______blue = _______ blue = _______Now list the genotypes of each of the four offspring below.Offspring 1   Offspring 2 Offspring 3 Offspring 4(Activity A continued on next page)Activity A (continued from previous page)3. Explain: Each rod-shaped structure is a chromosome. Real chromosomes contain hundreds or even thousands of genes. The simplified chromosomes shown in this Gizmo only contain genes that determine the insects’ colors.

How are the chromosomes of the offspring related to the chromosomes of the parents? ___________________________________________________________________________________________________________________________________________________________________________________________________________________________4.

Investigate: Any insect that has a mutation will be circled. Place your cursor on an insect with a mutation to examine its genotype. (If there are none in this generation, click Play and then Pause when a mutation appears.)

A. Examine the genotype of the mutated insect as well as the genotypes of its parentsto determine what the mutation is. What new gene appeared? __________________

B. Do you think this mutation is helpful, harmful, or neutral for the insect? Explain.___________________________________________________________________C. Click Play, and then click Pause after the birds have finished eating. Did the mutated insect survive? _______________________________________________________

5. Observe: Increase the Sim. speed by two levels. Click Play, and wait for a while. What occurs as time goes by? _______________________________________________________________________________________________________________________________________________________________________________________________________6. Explain: In wild populations, evolution is often caused by natural selection. Based on what you have observed, how does natural selection occur?