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ACT Science Unit 3: Evaluation of Models, Inferences, and Experimental Results

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Unit 3: Evaluation of Models, Inferences, and Experimental Results

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Question 1

Based on Set 1, what is the central observation Scientist 2 uses to argue AGAINST Scientist 1's temperature explanation?

A.Stomach contents of invasive fish contain juvenile natives.B.The native species are stable in a nearby lake with similar temperature trends but no invasive species.C.The native species spawn in a narrow temperature window.D.Native fish concentrate near cool water in summer.

Question 2

Based on Set 2, what finding would MOST SUPPORT Researcher 2 over Researcher 1?

A.Cold-start current draw is roughly

3 \times

warm-start draw in the same vehicle.B.Disconnected batteries at

- 15° C

still deliver less peak current than at

20° C

.C.Newer batteries are more reliable in the cold.D.Voltage drops smoothly with temperature.

Question 3

Based on Set 1, what additional experiment would best test BOTH hypotheses simultaneously?

A.Measure water temperature monthly for the next year.B.Survey the nearby lake for any new invasive species.C.Remove the invasive species from Lake Marisol and track both native population recovery and water temperature over multiple seasons.D.Add cooler water to Lake Marisol artificially.

Question 4

Based on Set 2, what observation would Researcher 2 expect that Researcher 1 would NOT necessarily expect?

A.Identical batteries deliver less peak current at

- 10° C

than at

25° C

even when not connected to an engine.B.Lighter-weight oil in the same engine reduces the magnitude of the cold-morning voltage decline.C.Battery voltage returns to normal once temperature rises.D.Voltage decline is proportional to temperature drop.

Question 5

Based on Set 2, what finding would MOST SUPPORT Researcher 1 over Researcher 2?

A.A battery removed from the engine entirely shows lower voltage at

- 15° C

than at

20° C

.B.Engines using lighter oil start more easily in the cold.C.Cold mornings draw more current from the battery during starting.D.Batteries fail completely after one cold winter.

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Question 6

Set 1 — Two scientists explain a decline in pond fish populations.

At Lake Marisol, populations of native fish have fallen by roughly $30%$ over the past decade. Water samples and biological surveys are available.

Scientist 1. The decline is driven by rising water temperatures. Average summer surface temperatures have risen by $1.6° C$ over the same period. Most of the native species spawn within a narrow temperature window, and warmer water also reduces dissolved oxygen. Surveys show that during the hottest summers, native fish are concentrated near a cool deep-water spring rather than in their usual shallow-water habitat, consistent with thermal stress.

Scientist 2. The decline is driven by an invasive predator fish introduced from a connected stream around the same time. Stomach contents from sampled invasive individuals contain juvenile native fish in roughly $60%$ of dissections, and the invasive population grew $4 \times$ over the decade. The same native species that declined in Lake Marisol have remained stable in a nearby lake where the invasive species is not present, despite similar temperature trends.

According to Scientist 1, which observation most directly supports the claim that temperature drives the native fish decline?

A.The

30%

population decline.B.Native fish concentrating near the cool deep-water spring in hot summers.C.The growth of the invasive fish population.D.Stable native populations in a nearby lake.

Question 7

Across Set 1 and Set 2, what common reasoning pattern do the scientists use to support their hypotheses?

A.Both pairs rely entirely on theoretical calculations.B.Both pairs cite empirical observations and propose a causal mechanism.C.Both pairs rely on the same kind of data.D.Both pairs reject all alternative hypotheses with statistical tests.

Question 8

Based on Set 1, which finding, if newly discovered, would MOST WEAKEN Scientist 1's hypothesis?

A.Native species can spawn over a wider temperature range than Scientist 1 assumed.B.Average summer temperatures have risen by

2.0° C

, not

1.6° C

, over the past decade.C.The deep-water spring is colder than previously measured.D.The invasive fish prefer warm water.

Question 9

Based on Set 1, which finding, if newly discovered, would MOST SUPPORT Scientist 2's hypothesis?

A.Native fish are observed near the cool spring in summer.B.Genetic analysis shows the invasive species evolved a taste for juveniles of multiple native species over the decade.C.Dissolved oxygen drops sharply during hot summers.D.The deep-water spring has remained at the same temperature.

Question 10

Based on Set 1, both scientists could agree on which of the following?

A.Native fish populations in Lake Marisol have declined.B.Rising temperatures are the primary driver of decline.C.The invasive species is the primary driver of decline.D.The nearby unaffected lake also has rising temperatures.

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Question 11

Based on Set 2, what would both researchers likely AGREE on?

A.Car batteries appear to perform worse in cold weather.B.Cold weather permanently damages batteries.C.Engine load is irrelevant to battery performance.D.Chemistry is the only relevant factor.

Question 12

Set 2 — Two researchers explain why a battery's voltage declines faster in cold weather.

Field technicians have noticed that car batteries lose voltage faster on cold mornings than on warm ones, especially when the temperature drops below $- 5° C$ .

Researcher 1. The decline is caused by reduced chemical reaction rates at low temperatures. Battery chemistry depends on ions moving through an electrolyte; at lower temperatures the ions move more slowly, so the rate at which the battery can deliver current is reduced. Lab measurements of identical batteries at temperatures from $- 20° C$ to $30° C$ show that the achievable peak current drops smoothly as temperature falls. This effect is fully reversible — when the battery warms up, it works normally again.

Researcher 2. The decline is caused by increased mechanical load on the engine in the cold. Engines are harder to crank in the cold because oil is more viscous and internal friction is higher, drawing far more current from the battery during a cold start than during a warm start. The battery is not failing chemically; it is being asked to deliver much more energy per start. As soon as engines start more easily (warmer weather, lighter oil), the same battery performs normally.

According to Researcher 1, what is the underlying cause of poor cold-weather battery performance?

A.Increased engine friction.B.Slower ion movement reducing chemical reaction rates.C.Permanent chemical damage to the battery.D.Increased oil viscosity.

ACT Science Unit 3: Evaluation of Models, Inferences, and Experimental Results — Free with Answer Explanations | Test Practice Hub