Expert Answers

Expert Answers

Short Written Assignment

View the Scientific Method Power Point Presentation here:

After reviewing the demonstration, design a hypothetical controlled experiment. In other words, you are going to focus your efforts on writing up hypothetical experiment design that includes "made up" results.

The experiment should help to determine whether drinking water that contains cadmium influences the rate of cancer occurrence in laboratory rats.

Be sure to identify the following:

control group

experimental group


hypothetical result

Then decide if you result support or reject your hypothesis. 

Just a little point of clarification - the questions at the end of the Power Point on scientific method are just to think about, you do not have to answer them and send them to me. 


NOTE: This lab has been adapted from “The Habitable Planet” curriculum

This lab uses a robust model of the carbon cycle to give you an intuitive sense for how carbon circulates through the atmosphere, biosphere, oceans, and crust. This model may be accessed at:

The model allows you to experiment with how human input to the carbon cycle might change global outcomes to the year 2100 and beyond. One particularly relevant human impact is the increase in atmospheric CO2 levels. Between the years 1850 and 2006, atmospheric concentrations have risen from 290 parts per million (ppm) to over 380 ppm - a level higher than any known on Earth in more than 30 million years. Using the model, you will experiment with the human factors that contribute to this rise and explore how different inputs to the carbon cycle might affect the concentrations of the greenhouse gas CO2.



Part 1: Run the simulation to 2100 with the default settings, and, using the Data Table (found in the Chapter 1 content), record the total carbon levels in each "sink" (terrestrial plants, soil, oil and gas, coal, surface ocean, and deep ocean) at 2050 and 2100. You will then use the data you collect from the model to answer the discussion questions at the end of the lab while thinking about how the model mimics real-life conditions.

Note: The default setting for the increase in fossil fuel use per year is 1.5%. This rate of increase is also a reasonable projection for the increase in global energy use, as the world's economies continue to ramp up and populations grow

Part 2: In many scenarios, the atmospheric concentration of CO2 is projected to increase beyond 700 ppm by the end of the century. However, this increase in atmospheric carbon doesn't account for all of the carbon released by burning fossil fuels.

To find out where all the carbon really goes, run the simulation again, one decade at a time. Record the total amount of carbon in the atmosphere (the number in the sky) and other carbon sinks (terrestrial plants, soil, surface ocean, and deep ocean), as carbon moves through the system. Note that 1 ppm of atmospheric CO2 is equivalent to 2.1 GT (Gigatons) of carbon. As you record your data, keep in mind that this is a simulation of real life. Think about the questions below.


If only one half of the flora in the world existed in 2100 (perhaps due to deforestation), what do you predict the atmospheric carbon level would be? How would you change the simulation to reflect this?

What is the relationship between increased carbon in the ocean and increased carbon in the soil? How else might carbon be transferred to soil?

What is the relationship between an increase in fossil fuel consumption and increased carbon in terrestrial plants? How might this change flora populations? What impact could twenty years at this level of consumption have on flora?

What is the relationship between an increase in total carbon concentration (the smokestack) and increased carbon in the ocean surface? How might this change marine life populations? What impact could fifty years at this level of emissions have on marine fauna? On marine flora?

In addition to circulating through the carbon cycle, where else might excess carbon be found? In fifty years, where would you be most likely to see excess carbon?

Which areas are most highly (and quickly) affected by an increase in carbon emissions (and increase in fossil fuel consumption)? How would these effects manifest themselves? What are the dangers/benefits to these areas?

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