Theory of Evolution - TOEFL Reading Practice Test with Answer Key

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Reading Instructions

• You have 15 minutes to read the following passage and answer all 10 questions related to it.  
• Most questions are worth 1 point, but the last question is worth more. The directions indicate how many points you will receive for that specific question. 
• The specific section/paragraphs have been provided again with the question for ease of understanding and quick solution.
• Some questions include a word or phrase that is highlighted in the question as well as in the paragraph for quick reference. 

Theory of Evolution

Charles Darwin's Theory of Evolution, considered one of the most significant and contentious scientific theories ever published, was formulated by Darwin, an English scientist of the 19th century renowned for his work "On the Origin of Species." In this seminal work, Darwin postulated that different species share common ancestors, diverging from these ancestors as they evolve, with new traits emerging through natural selection. This theory is founded on the assumption that life originated from non-life and progressed through indirect evolution. Despite its controversy, the Theory of Evolution has profoundly influenced modern scientific thought regarding the development of life. Darwin was born on February 12, 1809, in England. Although initially entering into medicine, Darwin chose to pursue his interest in natural science and embarked on a five-year journey aboard the H.M.S. Beagle, a British sloop belonging to the Royal Navy. Because of his experience aboard the Beagle, he laid the foundation for his Theory of Evolution while also establishing himself within the scientific community. Darwin's meticulous observations of fossils and wildlife during this voyage formed the basis of natural selection, the cornerstone of his evolutionary theory.

Natural selection plays a crucial role in forming the foundation of Darwin's Theory of Evolution. One fundamental aspect of Darwin's theory asserts that a species typically produces more offspring than can survive, yet each offspring is unique. Consequently, through processes like random mutation and genetic drift, offspring gradually acquire new traits and characteristics over time. Favorable traits that aid in survival are retained in the gene pool, while those that harm survival are gradually eliminated through selection. This mechanism of natural selection leads to gradual enhancements in a species over extended periods. Conversely, as a species evolves and improves, it diversifies, eventually resulting in the emergence of distinct species incapable of interbreeding.

Organisms can diverge and undergo evolutionary changes through natural selection, leading them to evolve beyond their original species. This process results in the development of more diverse and complex organisms as species separate from each other. This concept mirrors the selective breeding techniques humans have used with domesticated animals for many years. For instance, in horse breeding, individuals with desired traits like speed and endurance are selectively bred to produce offspring with these superior qualities. Consequently, successive generations of offspring are inherently inclined to excel as racing horses due to this selective breeding process.

Darwin's concept proposes that 'natural selection' drives 'selective breeding' in nature, serving as the engine of evolution. This theory offers a strong framework for understanding the gradual changes in organisms over time. However, it remains a theoretical construct that proves challenging to substantiate. A notable challenge to Darwin's theory concerns "irreducibly complex systems," which are systems requiring all their diverse components to function together; the absence of one component leads to the collapse of the entire system. With advancements in technology, modern science can now identify these intricate systems even at microscopic scales. Such highly interdependent systems, if prevalent, pose a challenge to Darwin's hypothesis regarding the mechanisms of evolution. Darwin himself acknowledged the seeming absurdity of natural selection producing complex organs like the eye, with its precise adjustments for focus, light intake, and correction of optical distortions.

Conclusively, "On the Origin of Species" is renowned as one of the most influential publications in history. Darwin's Theory of Evolution continues to be a topic of intense debate, serving as a focal point for controversy. While the theory is observable repeatedly, it remains unproven, and there are a plethora of instances that raise skepticism about natural selection and evolution processes. Darwin arrived at his conclusions through meticulous observation and his background as a naturalist. Despite the ongoing controversies surrounding his theory, Darwin stands out as one of the most significant scientists and naturalists in history, primarily due to his Theory of Evolution.

Directions: Now answer the questions. 

Paragraph 1

Charles Darwin's Theory of Evolution, considered one of the most significant and contentious scientific theories ever published, was formulated by Darwin, an English scientist of the 19th century renowned for his work "On the Origin of Species." In this seminal work, Darwin postulated that different species share common ancestors, diverging from these ancestors as they evolve, with new traits emerging through natural selection. This theory is founded on the assumption that life originated from non-life and progressed through indirect evolution. Despite its controversy, the Theory of Evolution has profoundly influenced modern scientific thought regarding the development of life. Darwin was born on February 12, 1809, in England. Although initially entering into medicine, Darwin chose to pursue his interest in natural science and embarked on a five-year journey aboard the H.M.S. Beagle, a British sloop belonging to the Royal Navy. Because of his experience aboard the Beagle, he laid the foundation for his Theory of Evolution while also establishing himself within the scientific community. Darwin's meticulous observations of fossils and wildlife during this voyage formed the basis of natural selection, the cornerstone of his evolutionary theory.

1. Which sentence closely resembles the following statement from paragraph 1 - "This theory is founded on the assumption that life originated from non-life and progressed through indirect evolution." ?
   1. The Theory of Evolution is based on the idea that non-organic compounds form the foundation of life and develop without guidance.
   2. By making specific assumptions, we can demonstrate that evolution is a universal process affecting both living and non-living entities.
   3. Darwin proposed that assuming life originated from non-organic compounds and evolved without guidance supports his theory.
   4. The contentious nature of the Theory of Evolution makes it difficult to form assumptions.

Paragraph 2

Natural selection plays a crucial role in forming the foundation of Darwin's Theory of Evolution. One fundamental aspect of Darwin's theory asserts that a species typically produces more offspring than can survive, yet each offspring is unique. Consequently, through processes like random mutation and genetic drift, offspring gradually acquire new traits and characteristics over time. Favorable traits that aid in survival are retained in the gene pool, while those that harm survival are gradually eliminated through selection. This mechanism of natural selection leads to gradual enhancements in a species over extended periods. Conversely, as a species evolves and improves, it diversifies, eventually resulting in the emergence of distinct species incapable of interbreeding.

1. What factors contribute to species acquiring new traits and characteristics, as stated in paragraph 2?
   1. Medication and longer lifespan
   2. Survival and choice
   3. Genetic mutation and drift
   4. Principles and theories

1. The term 'those' in paragraph 2 refers to
   1. gene pool
   2. survival
   3. natural selection
   4. traits and characteristics

Paragraph 3

Organisms can diverge and undergo evolutionary changes through natural selection, leading them to evolve beyond their original species. This process results in the development of more diverse and complex organisms as species separate from each other. This concept mirrors the selective breeding techniques humans have used with domesticated animals for many years. For instance, in horse breeding, individuals with desired traits like speed and endurance are selectively bred to produce offspring with these superior qualities. Consequently, successive generations of offspring are inherently inclined to excel as racing horses due to this selective breeding process.

1. What process is natural selection most similar to, as mentioned in paragraph 3?
   1. The branching of trees
   2. Breeding with selection
   3. Systems that are irreducibly complex
   4. The development of the human eye

1. What is the role of paragraph 3 in the passage?
   1. To illustrate the progression from simplicity to complexity in natural selection within the context.
   2. To cast uncertainty on the theory's credibility.
   3. To juxtapose with the concepts introduced in paragraph 2.
   4. To transition to the central idea outlined in paragraph 4.

Paragraph 4

Darwin's concept proposes that 'natural selection' drives 'selective breeding' in nature, serving as the engine of evolution. This theory offers a strong framework for understanding the gradual changes in organisms over time. However, it remains a theoretical construct that proves challenging to substantiate. A notable challenge to Darwin's theory concerns "irreducibly complex systems," which are systems requiring all their diverse components to function together; the absence of one component leads to the collapse of the entire system. With advancements in technology, modern science can now identify these intricate systems even at microscopic scales. Such highly interdependent systems, if prevalent, pose a challenge to Darwin's hypothesis regarding the mechanisms of evolution. Darwin himself acknowledged the seeming absurdity of natural selection producing complex organs like the eye, with its precise adjustments for focus, light intake, and correction of optical distortions.

1. Which of the following statements from paragraph 4 does not serve as evidence supporting the idea that proving natural selection is challenging?
   1. Expressing skepticism about natural selection's ability to account for the human eye's complexity
   2. Noting that the existence of irreducibly complex systems challenges evolutionary processes
   3. Highlighting the use of modern technology to demonstrate the existence of irreducibly complex systems
   4. Identifying selective breeding as a significant flaw in the theory of natural selection.

1. Directions: Look at the part of the passage that is displayed above. The letters (A), (B), (C), and (D) indicate where the following sentence could be added. 
   
   The five-year voyage proved to be a major turning point in his life. 
   
   (A) Darwin was born on February 12, 1809, in England. (B) Although initially entering into medicine, Darwin chose to pursue his interest in natural science and embarked on a five-year journey aboard the H.M.S. Beagle, a British sloop belonging to the Royal Navy. (C) Because of his experience aboard the Beagle, he laid the foundation for his Theory of Evolution while also establishing himself within the scientific community.(D)
   
   Where would the sentence best fit?
   1. A. Choice A
   2. B. Choice B
   3. C. Choice C
   4. D. Choice D

Paragraph 4

Darwin's concept proposes that 'natural selection' drives 'selective breeding' in nature, serving as the engine of evolution. This theory offers a strong framework for understanding the gradual changes in organisms over time. However, it remains a theoretical construct that proves challenging to substantiate. A notable challenge to Darwin's theory concerns "irreducibly complex systems," which are systems requiring all their diverse components to function together; the absence of one component leads to the collapse of the entire system. With advancements in technology, modern science can now identify these intricate systems even at microscopic scales. Such highly interdependent systems, if prevalent, pose a challenge to Darwin's hypothesis regarding the mechanisms of evolution. Darwin himself acknowledged the seeming absurdity of natural selection producing complex organs like the eye, with its precise adjustments for focus, light intake, and correction of optical distortions.

1. What was the author's intention in paragraph 4 when including a quote suggesting that the idea of natural selection forming the complexity of the human eye appears highly improbable?
   1. To present proof of the existence of irreducibly complex systems.
   2. To demonstrate a contradiction between natural selection and the fundamental principles of Darwin's Theory of Evolution.
   3. To bolster the argument that natural selection is foundational to Darwin's Theory of Evolution.
   4. To support the claim that natural selection is a theoretical concept that is challenging to validate. 

Paragraph 5

Conclusively, "On the Origin of Species" is renowned as one of the most influential publications in history. Darwin's Theory of Evolution continues to be a topic of intense debate, serving as a focal point for controversy. While the theory is observable repeatedly, it remains unproven, and there are a plethora of instances that raise skepticism about natural selection and evolution processes. Darwin arrived at his conclusions through meticulous observation and his background as a naturalist. Despite the ongoing controversies surrounding his theory, Darwin stands out as one of the most significant scientists and naturalists in history, primarily due to his Theory of Evolution.

1. What is the closest meaning of the word 'plethora' in paragraph 5?
   1. A. Large
   2. B. Sufficient 
   3. C. Essential
   4. D. Prominent

1. Instructions: Given below are six sentences. You need to choose three answer choices that represent the most significant ideas in the passage. Some answer choices are irrelevant or minor ideas not discussed in the passage. This question is worth 2 points.
   
    Answer Choices
   1. The process of natural selection elucidates the gradual transformation of species across generations.
   2. The Theory of Evolution delineates the divergence of species from a shared progenitor.
   3. Creationists vehemently oppose the foundational principles of the Theory of Evolution.
   4. Charles Darwin initially registered for medical studies.
   5. Darwin's publication 'On the Origin of Species' substantiated the Theory of Evolution.
   6. Darwin and his work 'On the Origin of Species' stand as pivotal influences in the realm of naturalist science.

Answer Key with Explanation for TOEFL iBT® Reading Passage - Theory of Evolution

1. Answer: D

Explanation: The sentence that closely resembles the statement "This theory is founded on the assumption that life originated from non-life and progressed through indirect evolution" from paragraph 1 is option D. This sentence acknowledges the foundational assumption of the Theory of Evolution (that life originated from non-life and evolved without direct guidance) while also highlighting the controversy and challenges associated with forming assumptions in this context. The other options either don't directly address the assumption about life's origin or don't mention the contentious nature of the theory, making them less relevant to the statement in question.

2. Answer: D

Explanation: The correct answer is option C. This is because paragraph 2 discusses how species acquire new traits and characteristics over time. It mentions processes like genetic mutation, where changes occur in the genetic material, and genetic drift, which refers to random changes in gene frequencies within a population. These factors directly contribute to the emergence of new traits and characteristics in a species. Options A, B, and D are not mentioned as factors contributing to the acquisition of new traits in the context of the passage.

3. Answer: C

Explanation: The term 'those' in paragraph 2 refers to Option C, natural selection. This is because the passage discusses how natural selection acts on the traits and characteristics of offspring. It mentions that favorable traits aiding in survival are retained in the gene pool, while traits that hinder survival are gradually eliminated through selection. Therefore, 'those' refers to the process of natural selection acting on traits within the gene pool.

4. Answer: C

Explanation: The correct answer is option C. In paragraph 3, the passage discusses how organisms can diverge and undergo evolutionary changes through natural selection, leading to the development of more diverse and complex organisms. The mention of "irreducibly complex systems" refers to systems that require all their diverse components to function together; the absence of one component leads to the collapse of the entire system. This concept is similar to natural selection because natural selection also relies on multiple components (genetic variations, environmental factors, etc.) working together for the process to function effectively. Options A, B, and D are not directly related to the concept of irreducibly complex systems or natural selection as discussed in the passage.

5. Answer: D

Explanation: The correct answer is option D, “To transition to the central idea outlined in paragraph 4”. Paragraph 3 serves as a transition between the discussion of natural selection and evolution in paragraph 2 and the central idea presented in paragraph 4. In paragraph 3, the passage discusses how organisms can diverge and undergo evolutionary changes through natural selection, leading to the development of more diverse and complex organisms. This concept sets the stage for the subsequent discussion in paragraph 4, which delves into the relationship between natural selection and selective breeding, further expanding on the mechanisms of evolution introduced earlier. Thus, paragraph 3 acts as a bridge that leads the reader from one aspect of evolutionary theory to another, highlighting the continuity of ideas in the passage.

6. Answer: B

Explanation: The correct answer is option B, “Noting that the existence of irreducibly complex systems challenges evolutionary processes”. This statement does not serve as evidence supporting the idea that proving natural selection is challenging; instead, it presents a counterargument or challenge to evolutionary processes. The statement suggests that the existence of irreducibly complex systems poses a challenge to Darwin's theory of natural selection. It does not directly support the idea that proving natural selection is challenging due to the complexity of certain biological structures. Options A, C, and D provide evidence or examples that contribute to the argument that proving natural selection can be challenging for various reasons.

7. Answer: A

Explanation: The sentence "The five-year voyage proved to be a major turning point in his life." would best fit in Choice A, right after the sentence "Darwin was born on February 12, 1809, in England." This placement makes sense chronologically, as it introduces Darwin's birth and then immediately discusses a significant event in his life, which is the five-year voyage aboard the H.M.S. Beagle. Placing the sentence in Choice B would disrupt the flow of information about Darwin's early life and career choices. Similarly, Choices C and D are not appropriate for inserting this sentence, as they are focused on different aspects of Darwin's life and work.

8. Answer: D

Explanation: The author's intention in paragraph 4, when including a quote suggesting that the idea of natural selection forming the complexity of the human eye appears highly improbable, is to support the claim that natural selection is a theoretical concept that is challenging to validate. The quote about the complexity of the human eye serves to highlight one of the challenges in natural selection theory. The intricacy and precision of certain biological structures, such as the eye, are cited as examples of features that might seem unlikely to have evolved solely through random processes like natural selection. This supports the broader argument that natural selection, while a foundational concept in Darwin's Theory of Evolution, faces challenges in explaining certain aspects of biological complexity. Therefore, choice D is the most appropriate because it aligns with the purpose of including the quote in the paragraph.

9. Answer: A

Explanation: The closest meaning of the word 'plethora' in paragraph 5 is Option A, large.

The term 'plethora' typically refers to an excessive or abundant quantity of something. In the context of the passage, it suggests that there are numerous instances or examples that raise skepticism about natural selection and evolution processes. This aligns with the idea of a large or abundant number of cases that contribute to skepticism or doubt. Therefore, choice A, "Large," is the most appropriate synonym for 'plethora' in this context.

10. Answer: D

Explanation: The table is completed correctly below. 

Charles Darwin's Theory of Evolution was a revolutionary idea that described how natural selection influences the evolution of species.

Answer Choices

A. The process of natural selection elucidates the gradual transformation of species across generations.

B. The Theory of Evolution delineates the divergence of species from a shared progenitor.

C. Creationists vehemently oppose the foundational principles of the Theory of Evolution.

D. Charles Darwin initially registered for medical studies.

E. Darwin's publication 'On the Origin of Species' substantiated the Theory of Evolution.

F. Darwin and his work 'On the Origin of Species' stand as pivotal influences in the realm of naturalist science.

Correct Choices

Choice A “The process of natural selection elucidates the gradual transformation of species across generations." This choice captures the central concept of natural selection and its role in the evolutionary process, which is a key idea in Darwin's Theory of Evolution as discussed in the passage.

Choice B "The Theory of Evolution delineates the divergence of species from a shared progenitor." This choice highlights another fundamental aspect of Darwin's theory, which is the idea that different species share a common ancestor and diverge over time, contributing to the overall understanding of evolution.

Choice E "Darwin's publication 'On the Origin of Species' substantiated the Theory of Evolution." This choice directly references the pivotal work by Darwin that presented his theory to the world and provided evidence and arguments supporting the Theory of Evolution.

Incorrect Choices

Choice C "Creationists vehemently oppose the foundational principles of the Theory of Evolution." This choice is incorrect because while the passage mentions the Theory of Evolution and its controversies, it does not specifically discuss creationists opposing it. The focus is more on Darwin's theory and the challenges it faces, rather than the opposition from creationists.

Choice D "Charles Darwin initially registered for medical studies." This choice is incorrect because it is a minor detail about Darwin's early life and education, which is not a central idea in summarizing the passage. The passage focuses on Darwin's Theory of Evolution, natural selection, challenges to the theory, and its impact on scientific thought.

Choice F "Darwin and his work 'On the Origin of Species' stand as pivotal influences in the realm of naturalist science." This choice is incorrect because while the passage acknowledges the significance of Darwin's work, it does not emphasize this as a major idea in summarizing the passage. The focus is on explaining Darwin's Theory of Evolution and discussing challenges to it, rather than highlighting Darwin's influence in naturalist science.

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