TOEFL Reading Practice Test #30

1. Paragraph 1 suggests that Miller and Urey’s experiment resulted in which of the following reactions in the scientific community when the results were published in 1953?

2. The word “resolved” in the passage is closest in meaning to:

3. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?
Highlighted sentence: Today most researchers who study early Earth do not believe that its atmosphere was primarily methane and ammonia, which would have been a strongly reducing atmosphere, where reducing means hydrogen-rich.

4. According to paragraph 2, why do scientists believe that Earth’s early atmosphere did not primarily consist of methane and ammonia?

5. According to paragraphs 2 and 3, after the early optimism about explaining how life on Earth emerged, scientists believed all of the following EXCEPT:

6. According to paragraph 4, why would hydrogen cyanide have been rare on the early Earth?

7. The word “Presumably” in the passage is closest in meaning to:

8. In paragraph 5, why does the author remark that most of the organic material brought to Earth by comets would have arrived by 3.8 billion years ago, the estimated time for when life on Earth began?

9. Look at the four squares [■] that indicate where the following sentence could be added to the passage.

Sentence: "Existing theories about the early atmosphere were used to help design the study."

Excerpt:
"[■] [1] A little more than 3.8 billion years ago is a good estimate of when life began on Earth. How it began remains speculative. [■] [2] There is no standard theory; there is instead a confusion of conflicting theories that attack the problem from different angles. [■] [3] This is a change from 1953 when a classic experiment on the origin of life was published. Then, Stanley Miller and Harold Urey had just completed their famous laboratory simulation of the conditions of an early Earth at the University of Chicago. When Miller and Urey let electric sparks course like lightning through an “atmosphere” of methane, ammonia, and hydrogen, which circulated above an “ocean” of boiling water, they found that a reddish substance, rich in amino acids, accumulated in their glass apparatus. Amino acids, when strung together in long folded chains, form proteins, and proteins are the building blocks of the living cell. [■] [4] From the spontaneous synthesis of amino acids to the spontaneous origin of life on the primitive Earth did not seem such a long way to go."

10. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas.
This question is worth 2 points.

Introductory sentence:
In 1953, the Miller-Urey experiment showed that amino acids form spontaneously under conditions then thought to be similar to those of early Earth.