The energy you use to walk from point A to point B is a result of several energy transformations from one form to another beginning with energy from the sun. The net result of these transformations is a. a loss of energy. b. fewer electrons. c. an increase in heat energy. d. an increase in usable energy. e. a decrease in entropy.

What are this chapter’s three big ideas? Explain how the Hubbard Brook Experimental Forest controlled experiments illustrated the three scientific principles of sustainability.

How would you respond to someone who tells you that:
a. he or she does not believe in biological evolution because it is "just a theory"?
b. we should not worry about air pollution because natural selection will enable humans to develop lungs that can detoxify pollutants.

Use the second law of thermodynamics to explain why we can use oil only once as a fuel, or in other words, why we cannot recycle its high-quality energy.

What is the key concept for this section? What happens to matter in an ecosystem? What is a nutrient cycle? Explain how nutrient cycles connect past, present, and future life. Describe the hydrologic cycle, or water cycle. Summarize the unique properties of water. What three major processes are involved in the water cycle? What is surface runoff? Define groundwater. What is an aquifer? What percentage of the earth’s water supply is available to humans and other species as liquid freshwater? Explain how human activities are affecting the water cycle in three ways. Explain how clearing a rain forest can affect local weather and climate (Core Case Study). Describe the carbon, nitrogen, phosphorus, and sulfur cycles, and explain how human activities are affecting each cycle.

What might be one possible reason for the greater fluctuations in the blue crab population?
a. Blue crabs are more highly influenced by rainfall patterns than striped bass.
b. Blue crabs have a much shorter life span ( 2 years) than striped bass and naturally have more variability in their population numbers.
c. Global warming patterns have caused an increase in the Chesapeake Bay temperatures causing increased crab spawning rates.
d. Increased sediment flow has disrupted striped bass migratory patterns causing a decline in their numbers.
e. Eutrophic dead zones in the Chesapeake Bay causing low dissolved oxygen levels have caused a decline in crab numbers.

Describe the threats to many of the world's amphibian species and explain why we should avoid hastening the extinction of any amphibian species through our activities.

Suppose someone wants you to invest money in an automobile engine, claiming that it will produce more energy than is found in the fuel used to run it. What would be your response? Explain.

Ecologists designed an experiment to determine whether nitrates or phosphates are more limiting to algae growth. A lake in Canada (Lake 226) was divided into two equal-sized sections by a vinyl curtain. Each sub-basin of the lake was then fertilized, one with nitrates and carbon and the other with phosphates, nitrates, and carbon. The amount of phytoplankton in the lake was then measured in each side, with the side of the lake with phosphates added showing a greater rate of phytoplankton growth.

Which of the below is the independent variable in this experiment? a. The location of the lakes b. The two lakes separated by a vinyl curtain c. The amount of phytoplankton growth d. The depth of the lakes e. The phosphate added to one side of the lake

What role does each of the following processes play in helping to implement the three scientific principles of sustainability:
(a) natural selection,
(b) speciation, and
(c) extinction?

How might we and other species be affected if all amphibians (Core Case Study) were to go extinct?

What two areas have the highest percentages of nonendemic species?

Respond to the following statements: a. Scientists have not absolutely proven that anyone has ever died from smoking cigarettes. b. The natural greenhouse effect theory—that certain gases such as water vapor and carbon dioxide help to warm the lower atmosphere—is not a reliable idea because it is just a scientific theory.

Population A contains 450,000 people and has a 3.3 percent annual growth rate. Population B has 900,000 people and a 1.8 percent annual growth rate. Which population would increase by more people in one year? Explain.