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

Scientist 1's entire argument is built around the idea of a singular, catastrophic event. The key evidence cited—the iridium layer and the Chicxulub crater—both point to a massive asteroid impact as the direct and primary cause of the mass extinction.

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

Scientist 1 states that the 'discovery of a worldwide layer of iridium... is the key evidence.' Scientist 2 acknowledges this evidence but offers an alternative explanation for it, stating 'The iridium layer could have been sourced from the Earth's mantle.' Therefore, both agree that the layer exists.

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

The core of the conflict is the primary mechanism of extinction. Scientist 1 argues for a sudden, external event (impact), while Scientist 2 argues for a long-term, internal process (volcanism). All other disagreements, such as the source of the iridium, stem from this central conflict.

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

Scientist 2's hypothesis is based on a 'gradual process' that 'stressed ecosystems to a breaking point long before the asteroid impact.' Finding evidence of a slow decline in biodiversity before the impact event would directly support this claim of a gradual, long-term cause rather than a single, sudden catastrophe.

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

Scientist 1 explicitly states that iridium is 'an element rare on Earth but common in asteroids.' This is the crucial link in the argument: the presence of an element common in asteroids, found in a worldwide layer at the exact time of the extinction, serves as the primary evidence for an asteroid impact.

ACT Practice Test

ACT Practice Test

FREE ACT Science: Conflicting Viewpoints Questions and Answers