FREE ACT Science: Conflicting Viewpoints Questions and Answers

Question 1

What is the central claim of Scientist 1? (Passage: Scientist 1: The extinction was caused by the impact of a large asteroid...
The discovery of a worldwide layer of iridium... is the key evidence.
Scientist 2: While an asteroid impact did occur, it was not the primary cause.
The extinction was a more gradual process driven by massive volcanic activity...)

Accepted Answer

A single, catastrophic asteroid impact was the primary cause of the mass extinction.

Answer

A gradual climate shift caused the mass extinction.

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Volcanic activity was a contributing factor to the asteroid impact.

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The iridium layer is a result of volcanic eruptions.

Question 2

Which of the following assertions would both Scientist 1 and Scientist 2 agree with?

Accepted Answer

A layer of iridium exists at the Cretaceous-Paleogene boundary.

Answer

The Chicxulub crater was caused by volcanic activity.

Answer

The extinction event was a gradual process.

Answer

An asteroid impact was the sole cause of the extinction.

Question 3

What is the fundamental point of disagreement between the two scientists?

Accepted Answer

Whether the primary cause of extinction was a sudden event or a gradual process.

Answer

Whether the Chicxulub crater exists.

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The source of the iridium found in the geological record.

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The time period in which the extinction occurred.

Question 4

Which of the following discoveries, if true, would most strongly support the hypothesis of Scientist 2?

Accepted Answer

Fossil records show a significant, steady decline in species diversity for a million years leading up to the iridium layer.

Answer

A second, smaller impact crater is found from the same time period.

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Analysis of the Chicxulub crater shows it was formed by an object much larger than previously thought.

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Atmospheric gas samples from ancient ice cores show stable CO2 levels throughout the late Cretaceous period.

Question 5

According to Scientist 1, the iridium layer is significant because:

Accepted Answer

Iridium is rare on Earth's surface but is abundant in asteroids.

Answer

Iridium is a byproduct of massive volcanic eruptions.

Answer

Iridium blocked sunlight, causing the global winter.

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Iridium is toxic to most forms of life.

Question 6

Scientist 2's explanation for the iridium layer is that it:

Accepted Answer

Was brought to the surface from the Earth's mantle by volcanoes.

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Was deposited by the asteroid impact, but was not the cause of death.

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Is not actually found worldwide.

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Is a result of chemical reactions from acid rain.

Question 7

The discovery that the specific isotopic ratio of iridium in the boundary layer perfectly matches that of known asteroids and is distinctly different from mantle-derived iridium would most damage the viewpoint of:

Accepted Answer

Scientist 2, because it would invalidate the proposed volcanic source for the iridium.

Answer

Scientist 1, because it would prove the impact was too small.

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Both scientists, because it introduces a new, unexplained variable.

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Neither scientist, because the source of iridium is not central to their arguments.