Science Assessment ~ Items ~ AP031006

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?

Let's start with the observation that the bear is still breathing in and out during hibernation, which means that there is matter flowing into and out of the bear during hibernation.

1. Which of the following molecules are being breathed in by the bear during hibernation? Choose all that apply.

A. Molecules of oxygen

B. Molecules of carbon dioxide

C. Molecules from the food the bear ate before hibernating

D. Molecules of water

2. Which of the following molecules are being breathed out by the bear during hibernation? Choose all that apply.

A. Molecules of oxygen

B. Molecules of carbon dioxide

C. Molecules from the food the bear ate before hibernating

D. Molecules of water

We also know that during hibernation bears are getting the energy they need to stay warm and survive the winter. This energy comes from a chemical process called cellular respiration that goes on inside the bears’ bodies.

3. How is breathing related to cellular respiration? To help show your thinking on this question, create a diagram in the space below. The diagram should clearly show what molecules are reacting and what molecules are being produced during cellular respiration.

In your diagram, consider the bear to be a system with inputs and outputs. Your diagram should include:

- A boundary separating what is inside and outside the bear

- The matter that enters and leaves the bear as it breaths in and out during hibernation

[Q3_AP31 Student Model]

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4. Explain how breathing is related to cellular respiration. Be sure to link the molecules that the bear breathes in and out to the cellular respiration process.

A. Drauglis / flickr

5. Now think about the fact that the bear loses weight during hibernation. Use your diagram to write an explanation for what caused the bears to decrease in mass during hibernation. Think about the difference in masses of the molecules the bear breathes in and out during hibernation. Be sure to refer to your diagrams in your explanation.

Details
Performance
NGSS

Topic: 3D Energy Tasks
Scoring Rubric: Q1; Student selects answer choice A

A. Molecules of oxygen; Q2; Student selects answer choice B

B. Molecules of carbon dioxide; Q3; 1. Student's model includes boundaries between systems

Model includes a boundary separating the inside of the bear from the surroundings.

2. Student's model includes the essential components including inputs and outputs

Model includes glucose/carbon containing molecules as a component of the bear system.

Model includes oxygen as an input into the bear system.

Model includes carbon dioxide as an output from the bear system.

Model includes water as an output from the bear system.

Note: The DCI does not explicitly mention that water is a product. So, it is up to the user to decide if water being a product is an essential element of a correct response.

3. Student's model shows the interactions between components

The model shows atoms in molecules rearranging to form different molecules by showing that the reactant molecules are different than the product molecules, typically by using an arrow that points from the reactants to the products.; Q4; Student states or uses a general science idea

Oxygen molecules that are breathed in are reactants of cellular respiration.

Carbon dioxide molecules that are breathed out are products of cellular respiration.

Water molecules that are breathed out are products of cellular respiration.

Note: The DCI does not explicitly mention that water is a product. So, it is up to the user to decide if water being a product is an essential element of a correct response.; Q5; 1. Student makes a claim that answers the question

The bear decreased in mass/lost weight because

Matter/atoms that was/were once part of the bear's body left/is no longer part of the bear's body.

The bear exhaled more mass than it took in.

Note: Students who explicitly state that matter is destroyed or not conserved should not receive the claim point.

2. Student uses the crosscutting concept about the flow of matter into and out of a system to provide evidence.

The bear breathes in oxygen molecules.

The bear breathes out carbon dioxide molecules

The bear breathes out water molecules. (optional)

3. Student states or uses science ideas

Carbon dioxide has more mass than oxygen.

Carbon-based food molecules already inside the bear are involved in a reaction (that produces carbon dioxide).

4. Student uses reasoning to link crosscutting concepts to the claim

There is a net loss of mass (weight, atoms, or matter) from the bear during hibernation because oxygen is entering the bear and carbon dioxide is leaving the bear, and carbon dioxide is heavier than oxygen.

OR

The carbon atoms that leave the body as part of carbon dioxide came from carbon-based molecules that were part of the bear's body, therefore, there is a net loss of mass (weight or atoms are also acceptable) from the bear during hibernation.

Percent of Points Earned

Chart showing distrubtion of responses for Item AP031006

Points Earned

	Avg. Earned	Possible	Percent
Q1	0.35	1	35%
Q2	0.11	1	11%
Q3	1.27	6	21%
Q4	0.17	3	6%
Q5	0.14	4	4%

Overall Task Difficulty

	Total Points Earned	Total Points Possible	Total Percent
	2.04	15	14%

n = 237

Note: The total percent is a weighted average based on the total number of points earned divided by the total number of points possible.

Science and Engineering Practices: SEP2 Develop a model to describe unobservable mechanisms.
SEP6 Construct an explanation using models or representations.
Crosscutting Concepts: CC4 Systems may interact with other systems; they may have sub-systems and be a part of larger complex systems.
CC5 Matter flows and cycles can be tracked in terms of the weight of the substances before and after a process occurs. The total weight of the substances does not change. This is what is meant by conservation of matter. Matter is transported into, out of, and within systems.
Disciplinary Core Ideas: PS3.D Cellular respiration in plants and animals involve chemical reactions with oxygen that release stored energy. In these processes, complex molecules containing carbon react with oxygen to produce carbon dioxide and other materials.

Science Assessment

Item AP031006: Create a model of cellular respiration and use it to explain how matter and energy flow into and out of a bear during hibernation.