Researchers of Prebiotic Chemical Reactions have been Testing the Theory that Early Life could have come About Through RNA Alone.

Reading Passage Question

Researchers of prebiotic chemical reactions have been testing the theory that early life could have come about through RNA alone, gradually giving way to a world in which RNA and DNA work together.

Experiments conducted in 1983 showed that RNA molecules can split themselves and recombine in new arrangements, leading to the conclusion that life could have begun without naturally occurring complex protein enzymes. That the protein could be formed by the elements at hand was demonstrated as early as 1953, in an experiment by Drs. Urey and Miller. They filled a sealed flask with substances considered to have been plentiful in the earth's prebiotic state—methane, ammonia, water vapour, hydrogen, and carbon dioxide—and subjected the mixture to simulated lightning strikes. Within weeks the mixture contained the amino acids necessary to build proteins. By experimenting further, Dr. Miller was able to create 13 of the 20 amino acids necessary for life.

The RNA theory was then generally accepted by most biologists, but the question remained: how could RNA exist without its requisite precursors, cytosine and uracil? This problem now appears to have been solved, again by Dr. Miller. He postulates that both substances could have been produced in the prebiotic ocean through a process that entails the evaporation of seawater, the freezing of seawater in the polar ice caps, and the mixing of the two in the ocean.

“Researchers of prebiotic chemical reactions have been testing the theory that early life could have come about through RNA alone.”- is a GMAT reading comprehension passage with answers. Candidates need a strong knowledge of English GMAT reading comprehension.

This GMAT Reading Comprehension consists of 7 comprehension questions. The GMAT Reading Comprehension questions are designed for the purpose of testing candidates’ abilities in understanding, analyzing, and applying information or concepts. Candidates can actively prepare with the help of GMAT Reading Comprehension Practice Questions.

Solution and Explanation

1. The passage is primarily concerned with

1. explaining how life evolved from complex proteins
2. discussing how a theory on the origins of life has been tested and expanded upon
3. contemplating the evolution of life from non-complex proteins
4. describing how researchers solved the problem of creating life from RNA
5. reexamining an outdated theory on the development of DNA from seawater and lightning

2. It can be inferred from the passage that RNA molecules

1. are among the most basic structures known to man
2. are more complicated structures than are DNA molecules
3. can form a variety of structures and combinations
4. contain methane, ammonia, and water vapour, among other components
5. only function once charged by electrical impulses

3. According to the passage, which of the following is true of the experiment performed by Drs. Urey and Miller in 1953?

1. RNA was fabricated out of simple prebiotic substances.
2. More than one dozen significant amino acids were synthesised.
3. The experiment took several weeks to complete.
4. Cytosine and uracil formed in the sealed beaker.
5. The experiment was conducted in a flask filled with protein enzymes.

4. Which of the following, if true, would most undermine Miller's argument (Text in Red)?

1. Climatic conditions in the prebiotic world were inhospitable to the formation of life.
2. The polar ice caps in the prebiotic world covered more than one-quarter of the Earth's oceans.
3. Recent research indicates that uracil could not have existed in the prebiotic world.
4. Atmospheric pressure in the prebiotic world was much lower, leading to a near-absence of rain.

Prebiotic RNA from the middle of ancient land masses has been found to contain only small amounts of uracil and cytosine.

5. The author cites the experiment performed by Drs. Urey and Miller (Text in Blue) in order to

1. explain in further detail how they reached their conclusion
2. point out the methodological flaws in their research
3. show that methane, ammonia, water vapour, hydrogen and carbon dioxide were present in the prebiotic world
4. challenge the 1953 experiment as technologically inadequate to determine the role of RNA in the formation of life
5. support the thesis of Drs. Miller and Urey with conclusive scientific evidence

Answer: A
Explanation: This option is correct because in the passage, the author introduces the experiment by Drs. Urey and Miller in the highlighted line discussed in the question.Firstly, he describes the experiment in detail. Then he mentions that the experiment successfully established that protein could be formed by the elements during the prebiotic world. Option A is correct.

6. The passage suggests which of the following about the prebiotic chemical reactions that brought about life?

1. Although the reactions can be recreated in the laboratory, scientists cannot understand how they occurred in nature.
2. There is little direct evidence to prove scientists’ theories about such reactions.
3. While RNA plays a part in prebiotic chemical reactions, DNA is critical to the formation of life.
4. The presence of cytosine and uracil in the prebiotic ocean precluded the development of life.
5. Complex ecosystems such as oceans and polar ice caps, are required for prebiotic chemical reactions to occur.

7. With which of the following statements about the origin of life would the author most likely agree?

1. Life in the prebiotic world must have derived from a combination of DNA and RNA.
2. without a greater understanding of the systems active in the prebiotic world, we cannot achieve a greater understanding of the origins of life.
3. Due to a paucity of data, the origins of life are poorly understood and difficult to explore.
4. While RNA is an important factor in enzyme production, it played a minor role in the creation of life.
5. Biologists play an important role in the study of prebiotic chemical reactions which formed the basis of human life.

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