Which of the following actions can reduce humanity's ecological footprint?a. reducing our dependence on fossil fuels;b. reducing meat consumption;c. living in higher density settlements;d. better management of human wastewater;e. all of the above

What are the three levels of biological diversity? Explain how human activities threaten each of these levels.

What is rapid eutrophication? What steps might be taken to slow this process?

The population size of mountain pine beetles in the American Northwest has long been held in check by freezing temperatures during the winters. As winters warm, populations of pine beetles are increasing, killing whitebark pine forest. Grizzly bears rely on the nuts of whitebark pine trees. Do you think climate change is affecting the fitness of the grizzly bear population?a. No, because climate change is not a problem yet.b. No, because climate change is affecting the beetles, not the bears.c. Yes, because climate change is decreasing the food supply of the bears, which means they will be less strong.d. Yes, because climate change is decreasing the food supply of the bears, which is likely to reduce their ability to survive or reproduce.

Suppose that record snows blanket your campus this winter. Your friend says this is proof that global warming isn't really occurring. What is the flaw in your friend's logic?a. The average temperature of the Earth is not actually increasing.b. Global warming refers to temperatures, but snow is a type of precipitation.c. While the average global temperature is increasing, local temperatures and precipitation (weather) will vary.d. Your friend is confusing global warming and global climate change.

One advantage of preserving more than one population of an endangered species at more than one location is .a. a lower risk of extinction of the entire species if a catastrophe strikes one location;b. higher levels of inbreeding in each population;c. higher rates of genetic drift in each population;d. lower numbers of heterozygotes in each population;e. higher rates of habitat fragmentation in the different locations

What are 'greenhouse gases'? Why are they important to life on Earth?

The maps shown here chronicle the loss of old-growth forest (more than 200 years old) that occurred in the United States. In your opinion, under what conditions is it ethical for conservationists who live in the United States to lobby government officials in Brazil, Indonesia, and other tropical countries to slow the rate of loss of old-growth forest?

During the Carboniferous period, plant growth was extensive but rates of decomposition slowed (probably due to the formation of vast, oxygen-poor swamp habitats). As a result, large amounts of biomass accumulated in terrestrial environments (much of this biomass is now coal). The fossil record indicates that atmospheric oxygen increased, atmospheric carbon dioxide decreased, and global temperatures dropped. Explain why.