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Item AP042006: Use a model to explain how matter that flows into and out of a hibernating bear leads to the bear losing mass. (CR version)

Prior to winter, black bears eat large quantities of food and gain up to 30 pounds of additional body weight. The food that the bears eat is made up of carbon-containing molecules such as glucose, carbohydrates, fats, and proteins. When winter begins, the bears go into dens or caves to hibernate. After several months of hibernation, they wake up and leave their dens. Scientists who study hibernating bears have found that bears lose a quarter of their body weight during hibernation.

Black bear den, NPS Photo / Harlan Kredit

Observations of hibernating bears show that they breathe in and out during hibernation, but they do not eat, drink, or "go to the bathroom."

How is it possible for bears to stay alive during hibernation if they don’t eat anything?

Below is a model showing one of the chemical reactions taking place inside a bear that will help you to understand how bears can stay alive during hibernation.

Using the model, answer the following questions about the processes happening inside the bear during hibernation.

1. How was the oxygen that the bear breathed in used by the bear to get energy?

2. Where did the carbon atoms that are in the carbon dioxide molecules that the bear breathed out come from?

3. Use the model to explain how the bear got the energy that it needed to stay alive during hibernation. Be sure to describe the role that molecules and chemical reactions play.

A. Drauglis / flickr

4.  Now think about the fact that the bear lost weight during hibernation. Use the model to write an explanation for what caused a bear to decrease in mass during hibernation. Think about the difference in masses of the molecules the bear breathes in and breathes out during hibernation. Be sure to refer to the model in your explanation.

Percent of Points Earned
Chart showing distrubtion of responses for Item AP042006
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Note: The total percent is a weighted average based on the total number of points earned divided by the total number of points possible.