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Question 1
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
65% (02:54) correct
35%
(02:21) wrong
based on 203
sessions
History
Date
Time
Result
Not Attempted Yet
Question 2
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
64% (00:53) correct 36%
(01:08) wrong
based on 186
sessions
History
Date
Time
Result
Not Attempted Yet
Question 3
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
69% (01:23) correct 31%
(01:25) wrong
based on 189
sessions
History
Date
Time
Result
Not Attempted Yet
Proteins are powerful enzymes that perform several tasks necessary to sustain life. One of these tasks is the production of DNA, a double-stranded molecule found in cells that carries the genetic instructions for all living organisms. Interestingly, DNA is required for the production of protein, so proteins cannot exist without DNA to specify their construction, and DNA cannot be produced or replicated without proteins. It would be impossible for cells to exist without both components, yet it is highly unlikely that they evolved simultaneously.
Some biologists considering this classic chicken-and-egg paradox have offered a solution known as the RNA World Hypothesis. This hypothesis is based on the knowledge that RNA, a single-stranded molecule similar to DNA, can also carry genetic information, and RNA can perform some of the same chemical reactions performed by proteins. The RNA World Hypothesis posits that RNA was originally the sole performer of both genetic and enzymatic functions in early cells. DNA and protein evolved later to take over these roles. However, this hypothesis depends on ribozymes (RNA molecules with enzymatic properties) being able to catalyze a greater variety of chemical reactions than any currently known natural ribozyme can.
Searches for new ribozymes with a wider range of enzymatic properties have had some success. Intriguingly, these new ribozymes were unable to match the speed with which proteins can perform their catalyst roles. This may suggest that RNA is relatively ineffective at carrying out these reactions, which could explain why proteins ultimately evolved to perform them instead. Then again, perhaps the best possible ribozymes for these reactions have simply not been found yet.
Some biologists considering this classic chicken-and-egg paradox have offered a solution known as the RNA World Hypothesis. This hypothesis is based on the knowledge that RNA, a single-stranded molecule similar to DNA, can also carry genetic information, and RNA can perform some of the same chemical reactions performed by proteins. The RNA World Hypothesis posits that RNA was originally the sole performer of both genetic and enzymatic functions in early cells. DNA and protein evolved later to take over these roles. However, this hypothesis depends on ribozymes (RNA molecules with enzymatic properties) being able to catalyze a greater variety of chemical reactions than any currently known natural ribozyme can.
Searches for new ribozymes with a wider range of enzymatic properties have had some success. Intriguingly, these new ribozymes were unable to match the speed with which proteins can perform their catalyst roles. This may suggest that RNA is relatively ineffective at carrying out these reactions, which could explain why proteins ultimately evolved to perform them instead. Then again, perhaps the best possible ribozymes for these reactions have simply not been found yet.
1. The author is primarily concerned with
A. reporting on the results of recent experiments to isolate new ribozymes
B. discussing a possible solution to a vexing puzzle in cellular evolution
C. examining the evidence that ribozymes evolved prior to DNA and proteins
D. refuting the argument that ribozymes are not versatile enough to provide the enzymatic and genetic components of early cells
E. explaining how DNA and proteins interact to provide cell function
A. reporting on the results of recent experiments to isolate new ribozymes
B. discussing a possible solution to a vexing puzzle in cellular evolution
C. examining the evidence that ribozymes evolved prior to DNA and proteins
D. refuting the argument that ribozymes are not versatile enough to provide the enzymatic and genetic components of early cells
E. explaining how DNA and proteins interact to provide cell function
2. The author uses the term "chicken-and-egg" in order to
A. illustrate the cyclical nature of the replication of DNA and the construction of proteins
B. demonstrate that the mechanisms for producing DNA and proteins are fundamentally enigmatic
C. point out the apparent contradiction that DNA could not exist without proteins having already evolved, and vice versa
D. show that an apparent conundrum in the evolution of the DNA molecule can be resolved if one also considers the simpler RNA molecule
E. provide a metaphor for the relationship between DNA and RNA
A. illustrate the cyclical nature of the replication of DNA and the construction of proteins
B. demonstrate that the mechanisms for producing DNA and proteins are fundamentally enigmatic
C. point out the apparent contradiction that DNA could not exist without proteins having already evolved, and vice versa
D. show that an apparent conundrum in the evolution of the DNA molecule can be resolved if one also considers the simpler RNA molecule
E. provide a metaphor for the relationship between DNA and RNA
3. All of the following can be inferred from information in the passage EXCEPT:
A. Scientists have yet to find ribozymes in nature that could perform enough to satisfy the RNA World Hypothesis.
B. In the RNA World Hypothesis, RNA would outperform DNA in its function of carrying genetic information.
C. Known ribozymes are not maximally effective at carrying out all of the known functions of proteins in modern cells.
D. A catalyst can be more effective when it performs its role more quickly.
E. DNA is not the only molecule that can carry an organism's genetic information.
A. Scientists have yet to find ribozymes in nature that could perform enough to satisfy the RNA World Hypothesis.
B. In the RNA World Hypothesis, RNA would outperform DNA in its function of carrying genetic information.
C. Known ribozymes are not maximally effective at carrying out all of the known functions of proteins in modern cells.
D. A catalyst can be more effective when it performs its role more quickly.
E. DNA is not the only molecule that can carry an organism's genetic information.
RC Butler 2023 - Practice Two RC Passages Everyday.
Passage # 288 Date: 21 Aug-2023
This question is part of RC Butler 2023. Click here for Details
Passage # 288 Date: 21 Aug-2023
This question is part of RC Butler 2023. Click here for Details
25 Feb 2024, 07:03
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The author's primary concern in the passage is discussing a potential solution to a well-known problem in the field of evolutionary biology—the origins of life and the interdependence of proteins and DNA. Let's examine each answer choice and why choice B is the correct one:
A. Reporting on the results of recent experiments to isolate new ribozymes
While the passage does mention the search for new ribozymes, it is not the main focus. This search is discussed in the context of the RNA World Hypothesis and the broader question of how life could have evolved. Hence, this choice is too narrow to be the primary concern of the passage.
B. Discussing a possible solution to a vexing puzzle in cellular evolution
This answer choice accurately captures the essence of the passage. The "vexing puzzle" is the chicken-and-egg problem of whether proteins or DNA came first, as both seem to be required for the other's existence. The RNA World Hypothesis is presented as a possible solution to this puzzle. The passage explores this hypothesis and its implications, making this the correct answer.
C. Examining the evidence that ribozymes evolved prior to DNA and proteins
The passage does discuss ribozymes and their potential role in early life. However, the primary purpose of the passage is not to examine the evidence that ribozymes evolved first but to discuss the RNA World Hypothesis as a whole, which includes the idea that ribozymes could have preceded DNA and proteins. Thus, this choice is too narrow in scope.
D. Refuting the argument that ribozymes are not versatile enough to provide the enzymatic and genetic components of early cells
The passage does address the limitations of ribozymes and mentions that no known natural ribozyme can catalyze as wide a variety of reactions as proteins can. However, the passage does not aim to refute the argument so much as it presents it as a possibility. The passage remains somewhat neutral and suggests that perhaps the best ribozymes have not been found yet. Therefore, "refuting" is too strong a word for what the passage does.
E. Explaining how DNA and proteins interact to provide cell function
While the interaction between DNA and proteins is an essential part of cell function and is mentioned in the passage, this is not the primary focus. The passage uses this interaction as a starting point to discuss the RNA World Hypothesis, rather than focusing on the interaction itself in detail.
A. Reporting on the results of recent experiments to isolate new ribozymes
While the passage does mention the search for new ribozymes, it is not the main focus. This search is discussed in the context of the RNA World Hypothesis and the broader question of how life could have evolved. Hence, this choice is too narrow to be the primary concern of the passage.
B. Discussing a possible solution to a vexing puzzle in cellular evolution
This answer choice accurately captures the essence of the passage. The "vexing puzzle" is the chicken-and-egg problem of whether proteins or DNA came first, as both seem to be required for the other's existence. The RNA World Hypothesis is presented as a possible solution to this puzzle. The passage explores this hypothesis and its implications, making this the correct answer.
C. Examining the evidence that ribozymes evolved prior to DNA and proteins
The passage does discuss ribozymes and their potential role in early life. However, the primary purpose of the passage is not to examine the evidence that ribozymes evolved first but to discuss the RNA World Hypothesis as a whole, which includes the idea that ribozymes could have preceded DNA and proteins. Thus, this choice is too narrow in scope.
D. Refuting the argument that ribozymes are not versatile enough to provide the enzymatic and genetic components of early cells
The passage does address the limitations of ribozymes and mentions that no known natural ribozyme can catalyze as wide a variety of reactions as proteins can. However, the passage does not aim to refute the argument so much as it presents it as a possibility. The passage remains somewhat neutral and suggests that perhaps the best ribozymes have not been found yet. Therefore, "refuting" is too strong a word for what the passage does.
E. Explaining how DNA and proteins interact to provide cell function
While the interaction between DNA and proteins is an essential part of cell function and is mentioned in the passage, this is not the primary focus. The passage uses this interaction as a starting point to discuss the RNA World Hypothesis, rather than focusing on the interaction itself in detail.
05 Sep 2024, 07:14
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In Question 2; not very convinced with the answer
Para 2 talk about
1. Evolution of DNA from RNA
Please help
Para 2 talk about
1. Evolution of DNA from RNA
Please help
