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A Ground Squirrel's Year Under the Ballfield

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A Ground Squirrel's Year Under the Ballfield

Use hibernation data to argue how a squirrel's body systems work together.

Part 1: A year of readings

Read the passage and Table 1. Use them to answer questions 1–5.

Asleep Under the Ballfield

1Prairie View Park is a city park with ball fields, a dog run and long strips of mowed meadow. The meadows are home to thirteen-lined ground squirrels, small striped animals that dig burrows under the grass. Every fall they disappear underground, and the park looks empty of them until spring. This summer, Hana Whitcombe joined a teen science program run by the park biologist, Dr. Amadou Ferris, who studies how the squirrels survive the winter.

2Dr. Ferris's team holds a permit to study the squirrels. A wildlife vet placed a tiny sensor under the skin of a few squirrels. Each sensor records the animal's body temperature, heart rate and breathing rate. The team also weighs each squirrel whenever it is caught in a live trap above ground. In winter, the soil around the burrows stays at about 5 °C.

3A hibernating ground squirrel does not eat for months. Its cells live on fat that it stored in its body before winter, and its blood carries that fuel to the cells. Hibernation is also not one long sleep. Every 1 to 3 weeks, a squirrel warms itself back up to its normal temperature for about half a day, then cools down again. Dr. Ferris says these wake-ups use a large share of the stored energy a squirrel spends all winter.

4During a wake-up, the squirrel's large leg and back muscles shiver, which releases thermal energy. The wake-up begins even though the burrow is still cold, because the brain sends the signals that start it. Hana's job this summer is to turn the sensor records from one squirrel, S-14, into tables for the park's visitor center.

Table 1: Squirrel S-14 Through the Year
Time of year	Activity	Body temp (°C)	Heart (beats/min)	Breaths per min	Mass (g)
July	Active	37	300	100	160
September	Active, eating a lot	37	280	90	240
January	Hibernating	5	5	2	not weighed
March	Hibernating	5	5	2	not weighed
Late April	Active again	37	300	100	150

1.

Use Table 1.

From September to late April, S-14's mass fell by g.

2.

Use Table 1.

In January, S-14's heart beat fewer times per minute than in July.

3.

In January, S-14's heart rate and breathing rate were both far lower than in summer. Which explanation best links the two changes?

A. The squirrel had stored extra oxygen in its fat, so it did not need to breathe until spring.B. The heart stopped pumping during hibernation, so the lungs had to move the blood instead.C. The brain stopped sending signals, so the heart and lungs slowed down with no control.D. The cold cells used much less oxygen and fuel, so the lungs and heart had less to deliver.

4.

Use paragraph 3 and Table 1. Why was S-14's mass gain from July to September important for surviving the winter?

A. The extra mass made its heart beat faster, which kept its body at 37 °C all winter.B. Its stored fat kept it from waking up, so it slept straight through until late April.C. Its digestive system took in extra food that was stored as fat, which its blood carried to cells all winter.D. The extra mass was water, which its cells could drink while the burrow stayed frozen.

5.

Circle each observation that is evidence that S-14's body systems were still working during the months it hibernated.

Part 2: One winter wake-up

Use the passage and Table 2 to answer questions 6–11.

Table 2: S-14's Wake-Up on February 9
Minutes after start	Body temp (°C)	Heart (beats/min)	Breaths per min	Shivering?
0	5	5	2	No
30	8	150	20	Yes, slight
60	15	280	60	Yes
90	26	350	110	Yes
120	36	380	120	Yes

6.

Use Table 2.

From 60 to 120 minutes, S-14's body temperature rose by °C.

7.

In the first 30 minutes, S-14's heart rate rose from 5 to 150 beats per minute, but its body warmed by only 3 °C. What does this pattern suggest?

A. The heart sped up first, ready to carry oxygen and fuel to the muscles that warm the body.B. The heart warmed the body by itself, so the muscles had no part in the wake-up.C. The heart sped up because the burrow got warmer, and the warm soil heated the squirrel.D. The heart beat faster to slow the warming, so the body would stay near 5 °C.

8.

Sort each event during a wake-up by the organ system that mainly carries it out.

9.

Which list goes in order from the smallest level of organization to the largest?

A. Heart, heart muscle tissue, heart muscle cell, circulatory systemB. Heart muscle cell, heart muscle tissue, heart, circulatory systemC. Heart muscle cell, heart, heart muscle tissue, circulatory systemD. Heart muscle tissue, heart muscle cell, heart, circulatory system

10.

One winter, loud construction near the park makes a squirrel wake up five extra times. Which prediction fits the data and the passage best?

A. It will likely be lighter in spring, since shivering and a fast heart use up more of its stored fat.B. It will likely be lighter in spring, since its heart beats about 5 times a minute while it is awake.C. It will likely weigh about the same in spring, since wake-ups use very little of its stored energy.D. It will likely be heavier in spring, since its stomach can fill up on stored seeds while it is awake.

11.

A visitor at the park says, "During hibernation, a squirrel's body just switches off, like a machine that has been unplugged." Argue against this. Write a claim, give evidence from both tables and the passage, and explain how at least three organ systems keep working together.