Coral Bleaching - TOEFL Reading Practice Test

To ace the TOEFL iBT^® exam, mastering academic texts in English is crucial for success in the TOEFL Reading section. This segment mirrors the challenges of reading in English-speaking academic environments, assessing skills like identifying main ideas, extracting details, making inferences, and recognising text structure. Consistent practice is the key to excelling in this section. 

Our practice tests closely mimic the format and writing style of the actual exam, ensuring that you feel prepared and self-assured on  the test day. Therefore, join us in taking the TOEFL Practice Test centered on the passage 'Coral Bleaching' to familiarise yourself with the test format and note the areas for improvement!

Reading Instructions

• You have 15 minutes to read the following passage and answer all 9 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. 

Coral Bleaching

Coral reefs, often called the "rainforests of the sea," are some of the most diverse and productive environments on Earth. These complex structures, formed by colonies of tiny coral polyps, provide important habitats for many marine species. They also support local fisheries and protect coastlines from erosion and storm damage. However, these vibrant environments are increasingly threatened by human activities, especially climate change. One of the most alarming issues related to these threats is coral bleaching, a process where corals expel the mutualistic algae known as zooxanthellae that live within their tissues. This expulsion leads to a loss of color. It also greatly reduces the corals' energy sources, ultimately putting their survival and the many species that depend on them at risk.

The main trigger for coral bleaching is higher sea temperatures, which can happen during periods of prolonged heat stress. For example, when water temperatures rise just 1-2 degrees Celsius above the normal range, corals may start to expel their zooxanthellae. These algae are important for the corals' health, as they provide up to 90% of the energy that corals need through photosynthesis. Without these algae, corals not only lose their vibrant colors but also become more at risk of disease, starvation, and eventual death. Historical data show that significant bleaching events have become more frequent, with notable occurrences recorded in 1998, 2010, and 2016, each leading to widespread coral death across various regions. However, while temperature increases are a well-documented cause, the exact ways in which corals respond to thermal stress remain an area of ongoing research.

In addition to higher temperatures, other factors contribute to coral bleaching. Ocean acidification, a direct result of increased atmospheric carbon dioxide levels, poses a major threat to coral health. As CO2 is absorbed by seawater, it reacts to form acid, which lowers the ocean's sourness. This change in acidity can weaken the corals' ability to build their calcium carbonate skeletons. Furthermore, pollution from agricultural runoff, overfishing, and coastal development can increase the stress on coral reefs, making them even more at risk of bleaching events. The dependence of these factors creates a complex web of challenges that corals must manage to survive. This raises questions about the strength of these environments in the face of rapid environmental change.

The ecological effects of coral bleaching go beyond the immediate loss of coral species. Coral reefs are critical habitats for many marine organisms, including fish, mollusks, and crustaceans. The decline of coral health can lead to a chain reaction throughout the marine food web, disrupting the balance of these environments. For example, many fish species rely on coral reefs for shelter and breeding grounds. As coral cover decreases, these fish populations may decline, leading to reduced biodiversity and altered community structures. Moreover, the loss of coral reefs can have significant economic effects, especially for coastal communities that depend on fishing and tourism for their livelihoods. The dependence of marine life and human economies highlights the urgency of addressing the factors contributing to coral bleaching.

In response to the growing threat of coral bleaching, scientists and conservationists are exploring various strategies to improve the restoration of coral reefs. One promising approach involves the selective breeding of heat-resistant coral species, which may be better suited to withstand higher temperatures. Also, efforts to establish marine protected areas can help reduce some of the stressors linked to human activities, allowing coral ecosystems to recover and thrive. Restoration projects, such as coral gardening and transplantation, aim to rehabilitate damaged reefs and promote the growth of healthy coral populations. However, these efforts require significant resources and long-term commitment to be effective. Critics argue that while these strategies may provide temporary relief, they do not tackle the root causes of climate change, which must be addressed to ensure the long-term survival of coral reefs.

The importance of addressing coral bleaching cannot be overstated, as the health of coral reefs is closely linked to the overall health of marine ecosystems and the well-being of human communities. As climate change continues to pose a serious challenge, it is essential that global efforts are increased to reduce greenhouse gas emissions and protect these important ecosystems. While the future of coral reefs remains uncertain, ongoing research and conservation initiatives offer hope for their survival. Furthermore, questions remain about how well coral species can adapt to changing environmental conditions and the potential for new technologies to help in their preservation. Finally, the fate of coral reefs serves as a strong reminder of the connection between human activities and the natural world, highlighting the urgent need for eco-friendly practices that protect these irreplaceable ecosystems for future generations.

Directions: Once you have read the passage, answer the following questions.

Paragraph 1 

Coral reefs, often called the "rainforests of the sea," are some of the most diverse and productive environments on Earth. These complex structures, formed by colonies of tiny coral polyps, provide important habitats for many marine species. They also support local fisheries and protect coastlines from erosion and storm damage. However, these vibrant environments are increasingly threatened by human activities, especially climate change. One of the most alarming issues related to these threats is coral bleaching, a process where corals expel the mutualistic algae known as zooxanthellae that live within their tissues. This expulsion leads to a loss of color. It also greatly reduces the corals' energy sources, ultimately putting their survival and the many species that depend on them at risk.

1. According to paragraph 1, what is one of the main threats to coral reefs?
   1. Overfinishing
   2. Climate change
   3. Coastal Development
   4. Pollution

1. In paragraph 1, the author mentions all of the following as benefits provided by coral reefs EXCEPT:: 
   1. They support local fisheries.
   2. They provide habitats for marine species.
   3. They prevent coastal erosion. 
   4. They are the primary source of freshwater. 

Paragraph 2

The main trigger for coral bleaching is higher sea temperatures, which can happen during periods of prolonged heat stress. For example, when water temperatures rise just 1-2 degrees Celsius above the normal range, corals may start to expel their zooxanthellae. These algae are important for the corals' health, as they provide up to 90% of the energy that corals need through photosynthesis. Without these algae, corals not only lose their vibrant colours but also become more at risk of disease, starvation, and eventual death. Historical data show that significant bleaching events have become more frequent, with notable occurrences recorded in 1998, 2010, and 2016, each leading to widespread coral death across various regions. However, while temperature increases are a well-documented cause, the exact ways in which corals respond to thermal stress remain an area of ongoing research.

1. What can be inferred from paragraph 2 about the relationship between temperature and coral health?
   1. Higher temperatures always lead to coral bleaching.
   2. Corals can adapt to slight increases in temperature without harm.
   3. Temperature increases can trigger coral bleaching under certain conditions.
      
   4. Coral bleaching is solely caused by temperature fluctuations.

Paragraph 3

In addition to higher temperatures, other factors contribute to coral bleaching. Ocean acidification, a direct result of increased atmospheric carbon dioxide levels, poses a major threat to coral health. As CO2 is absorbed by seawater, it reacts to form acid, which lowers the ocean's sourness. This change in acidity can weaken the corals' ability to build their calcium carbonate skeletons. Furthermore, pollution from agricultural runoff, overfishing, and coastal development can increase the stress on coral reefs, making them even more at risk of bleaching events. The dependence of these factors creates a complex web of challenges that corals must manage to survive. This raises questions about the strength of these environments in the face of rapid environmental change.

1. Why does the author mention ocean acidification in paragraph 3?  
   1. To highlight another significant threat to coral reefs.
   2. To explain how corals can adapt to changing conditions.
   3. To suggest that temperature is the only factor affecting coral health.
   4. To argue that pollution is the primary cause of coral bleaching.

Paragraph 4

The ecological effects of coral bleaching go beyond the immediate loss of coral species. Coral reefs are critical habitats for many marine organisms, including fish, mollusks, and crustaceans. The decline of coral health can lead to a chain reaction throughout the marine food web, disrupting the balance of these environments. For example, many fish species rely on coral reefs for shelter and breeding grounds. As coral cover decreases, these fish populations may decline, leading to reduced biodiversity and altered community structures. Moreover, the loss of coral reefs can have significant economic effects, especially for coastal communities that depend on fishing and tourism for their livelihoods. The dependence of marine life and human economies highlights the urgency of addressing the factors contributing to coral bleaching.

1. In paragraph 4, the word "disrupting" is closest in meaning to:  
   1. Maintaining 
   2. Disturbing
   3. Enhancing
   4. Supporting

Paragraph 5

In response to the growing threat of coral bleaching, scientists and conservationists are exploring various strategies to improve the restoration of coral reefs. One promising approach involves the selective breeding of heat-resistant coral species, which may be better suited to withstand higher temperatures. Also, efforts to establish marine protected areas can help reduce some of the stressors linked to human activities, allowing coral ecosystems to recover and thrive. Restoration projects, such as coral gardening and transplantation, aim to rehabilitate damaged reefs and promote the growth of healthy coral populations. However, these efforts require significant resources and long-term commitment to be effective. Critics argue that while these strategies may provide temporary relief, they do not tackle the root causes of climate change, which must be addressed to ensure the long-term survival of coral reefs.

1. Which of the following sentences best expresses the essential information in the following text from paragraph 5?

 "One promising approach involves the selective breeding of heat-resistant coral species, which may be better suited to withstand higher temperatures."   

1. 1. Scientists are breeding coral species that can survive in warmer waters.
   2. Coral species are being bred to increase their diversity.
   3. Heat-resistant coral species are being selectively bred for aesthetic purposes.
   4. Selective breeding of coral species is a new and untested approach.

Paragraphs 4

The importance of addressing coral bleaching cannot be overstated, as the health of coral reefs is closely linked to the overall health of marine ecosystems and the well-being of human communities. As climate change continues to pose a serious challenge, it is essential that global efforts are increased to reduce greenhouse gas emissions and protect these important ecosystems. While the future of coral reefs remains uncertain, ongoing research and conservation initiatives offer hope for their survival. Furthermore, questions remain about how well coral species can adapt to changing environmental conditions and the potential for new technologies to help in their preservation. Finally, the fate of coral reefs serves as a strong reminder of the connection between human activities and the natural world, highlighting the urgent need for eco-friendly practices that protect these irreplaceable ecosystems for future generations.

1. What is the main purpose of paragraph 6? 
   1. To discuss the economic benefits of coral reefs.
   2. To emphasise the need for urgent action against climate change.
   3. To outline the history of coral bleaching.
   4. To describe the various species of coral.

Paragraph 5

The importance of addressing coral bleaching cannot be overstated, as the health of coral reefs is closely linked to the overall health of marine ecosystems and the well-being of human communities. (A) As climate change continues to pose a serious challenge, it is essential that global efforts are increased to reduce greenhouse gas emissions and protect these important ecosystems. (B) While the future of coral reefs remains uncertain, ongoing research and conservation initiatives offer hope for their survival. (C) Furthermore, questions remain about how well coral species can adapt to changing environmental conditions and the potential for new technologies to help in their preservation. (D) Finally, the fate of coral reefs serves as a strong reminder of the connection between human activities and the natural world, highlighting the urgent need for eco-friendly practices that protect these irreplaceable ecosystems for future generations.

1. In paragraph 5, there is a missing sentence. The paragraph shows four letters  (A),  (B),  (C),  (D) that indicate where the following sentence could be added. 
   

   "Effective conservation strategies can mitigate some of the impacts of climate change." 

   Where would the sentence best fit? 

   1. Option A
   2. Option B
   3. Option C
   4. Option D
      

Prose Summary Questions

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 in the passage. This question is worth 2 points.

1. Coral bleaching poses a significant threat to marine ecosystems and human communities.  
   
   
   1. Coral reefs are vital for marine biodiversity and human economies.
   2. The main cause of coral bleaching is higher sea temperatures.
   3. Coral species can easily adapt to changing environmental conditions.
   4. Conservation efforts are essential to mitigate the effects of coral bleaching.

Hold on!  Before checking your answers and matching them, explore the TOEFL Exam Pattern and Syllabus!

Answer Key with Explanation for TOEFL Reading Passage - Coral Bleaching

1.  Answer: B

Explanation:  Paragraph 1 explicitly states that coral reefs are increasingly threatened by human activities, particularly climate change. While overfishing, coastal development, and pollution are mentioned as threats, climate change is highlighted as a primary concern, making it the correct answer.

2. Answer: D

Explanation: The passage lists several benefits of coral reefs, including supporting local fisheries, providing habitats for marine species, and preventing coastal erosion. However, it does not mention that coral reefs are a source of freshwater, making option D the correct choice as it is the only statement that is not supported by the text.

3. Answer: C

Explanation: The correct answer is option C.  The passage indicates that coral bleaching is triggered by higher sea temperatures, specifically when temperatures rise 1-2 degrees Celsius above normal. This suggests that while temperature increases can lead to bleaching, it is conditional and not absolute, making option C the most accurate inference.

4. Answer: A

Explanation: The correct answer is option A. The author mentions ocean acidification in paragraph 3 to illustrate that, in addition to higher temperatures, there are other significant threats to coral health. This serves to broaden the understanding of the challenges faced by coral reefs, making option A the correct answer.

5. Answer: B

Explanation: In paragraph 4, "disrupting" refers to causing a disturbance or interruption in the balance of marine ecosystems. The closest synonym among the options provided is "disturbing," which conveys a similar meaning of causing disruption.

6. Answer: A

Explanation: The correct answer is option A. This sentence captures the essential information from the original text by summarising the idea that scientists are selectively breeding heat-resistant coral species to help them withstand higher temperatures. It conveys the main point without unnecessary details, making it the best choice.

7. Answer: B

Explanation: The correct answer is option B. The main purpose of paragraph 6 is to stress the importance of addressing coral bleaching and the associated threats posed by climate change. The paragraph calls for increased global efforts to reduce greenhouse gas emissions, highlighting the urgency of the situation.

8. Answer: B

Explanation: The correct answer is option B. The missing sentence about effective conservation strategies fits best after the sentence discussing the uncertainty of the future of coral reefs. It logically connects the idea of ongoing research and conservation initiatives with the potential to mitigate climate change impacts, making option B the most appropriate placement.

9. Answer: A, B, D

Explanation: Option A is correct because the passage discusses the vital role of coral reefs in marine biodiversity and human economies. Option B is correct as it identifies higher sea temperatures as the main cause of coral bleaching, which is a central theme of the passage. Option D is correct because the passage emphasizes the importance of conservation efforts to mitigate the effects of coral bleaching. Option C is incorrect as the passage does not suggest that coral species can easily adapt to changing conditions; rather, it raises questions about their adaptability.

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