Free Practice Question
RC · Reading Comprehension
505-555
Short Passage - Science
Reading Passage
Since 1953, many experimental attempts to synthesize the chemical constituents of life under ‘primitive Earth conditions’ have been performed, but none of these experiments have produced anything approaching the complexity of the simplest organism. They have demonstrated, however, that a variety of the complex molecules currently making up living organisms could have been present in the early ocean and atmosphere, with only one limitation: such molecules are synthesized far less readily when oxygen-containing compounds dominate the atmosphere. Therefore some scientists postulate that the Earth's earliest atmosphere, unlike that of today, was dominated by hydrogen, methane, and ammonia. From these studies, scientists have concluded that the surface of the primitive Earth was covered with oceans containing the molecules fundamental to life. Although, at present, scientists cannot explain how these relatively small molecules combined to produce larger, more complex molecules, some scientists have precipitously ventured hypotheses that attempt to explain the development, from these larger molecules, of the earliest self-duplicating organisms.
The primary purpose of the passage is to
Answer Choices
Correct answer marked belowA
point out that theories about how life developed on Earth have changed little since 1953
B
warn of increasing levels of hydrogen, methane, and ammonia in the Earth's atmosphere
describe the development since 1953 of some scientists' understanding of how life began on Earth
Correct
D
demonstrate that the synthesis of life in the lab-oratory is too difficult for modern technology
E
describe how primitive atmospheric conditions produced the complex molecules of living organisms
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What it tests
Your ability to understand a passage, its structure, and what the author is really saying. At the 505-555 level, accuracy and speed both matter.
Common trap
Answering from memory or outside knowledge instead of strictly from the passage.
Details
Difficulty
505-555
Type
RC
Category