[ 토플 ] 📘 TOEFL Reading 심화 Day 16

📘 TOEFL Reading 심화 Day 16

주제: The Ecology of Coral Reefs (산호초 생태계)

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1️⃣ Vocabulary (고난도 아카데믹 단어 10개 – 글 형식)

symbiosis (noun): 공생 관계
예: Coral reefs depend on symbiosis between coral polyps and algae.

photosynthesis (noun): 광합성
예: Algae provide energy to corals through photosynthesis.

calcify (verb): 석회질로 굳다, 석회화하다
예: Corals calcify to build strong skeletons that form reef structures.

bleaching (noun): 백화 현상 (산호의 색이 사라지는 현상)
예: Rising sea temperatures cause coral bleaching and death.

ecosystem (noun): 생태계
예: Coral reefs are among the most diverse ecosystems on Earth.

biodiversity (noun): 생물 다양성
예: The biodiversity of coral reefs rivals that of tropical rainforests.

resilience (noun): 복원력, 회복력
예: Some coral species show remarkable resilience to temperature changes.

sedimentation (noun): 퇴적, 침전
예: Excessive sedimentation from coastal development can smother reefs.

acidification (noun): 산성화
예: Ocean acidification weakens coral skeletons and slows growth.

mitigation (noun): 완화, 경감
예: Effective mitigation efforts can help preserve coral ecosystems.

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2️⃣ Reading Passage (~880 words)

The Ecology of Coral Reefs

Coral reefs are among the most biologically diverse and ecologically complex systems on the planet. Often referred to as the “rainforests of the sea,” they cover less than one percent of the ocean floor but support nearly one-quarter of all marine species. This extraordinary productivity arises from a delicate balance of biological interactions and environmental stability that has evolved over millions of years.

At the core of every coral reef lies the coral animal itself—a small, soft-bodied polyp that lives in colonies. These polyps secrete calcium carbonate, forming the hard skeletons that build reef structures. Yet the true foundation of reef ecology depends on a partnership far smaller and more intricate: the symbiosis between coral polyps and microscopic algae called zooxanthellae. The algae live within coral tissues, conducting photosynthesis to produce oxygen and nutrients. In exchange, the coral provides the algae with shelter and carbon dioxide. This mutualistic relationship fuels the reef’s remarkable productivity even in nutrient-poor tropical waters.

However, the same dependency that sustains coral reefs also makes them highly vulnerable. When ocean temperatures rise—even by just one or two degrees Celsius—the symbiotic relationship breaks down. The algae are expelled, leaving the coral pale and starving in a process known as bleaching. Without their algal partners, corals lose their primary energy source, and prolonged bleaching can lead to mass mortality events. As climate change drives more frequent and intense heatwaves, bleaching has become a global crisis, threatening the very existence of these ecosystems.

Coral reefs also face multiple local stressors. Overfishing disrupts ecological balance by removing key species that control algae growth. Coastal development increases sedimentation, which blocks sunlight and smothers corals. Pollution, particularly from agricultural runoff, introduces excess nutrients that promote algal blooms. Together, these pressures weaken reef resilience—the ability to recover from disturbances.

Another major threat arises from ocean acidification. As the ocean absorbs carbon dioxide from the atmosphere, chemical reactions lower pH levels, reducing the availability of carbonate ions essential for calcification. This process weakens coral skeletons and slows their growth, leaving them more susceptible to storm damage. The combined effects of warming and acidification represent an unprecedented challenge for coral survival.

Despite these threats, coral reefs demonstrate remarkable adaptability. Some species can host more heat-tolerant strains of algae, while others expand into deeper or cooler waters. Restoration projects also show promise: scientists cultivate coral fragments in underwater nurseries and transplant them to damaged areas. While such efforts cannot replace natural resilience, they highlight human innovation in conservation science.

The ecological importance of coral reefs extends far beyond their beauty. They provide coastal protection by dissipating wave energy, preventing erosion, and sheltering shorelines. Economically, reefs support fishing industries and tourism worth billions of dollars annually. More subtly, they serve as genetic reservoirs, offering potential medical compounds for future use. Their loss would thus represent not only an ecological catastrophe but a profound human and economic one.

Preserving coral reefs requires coordinated global action. Mitigation of greenhouse gas emissions is essential to curb warming and acidification. Locally, reducing pollution, establishing marine protected areas, and promoting sustainable fishing can help restore reef health. Education and community engagement are equally critical—local stewardship often proves the most effective form of protection.

Ultimately, the story of coral reefs is one of both fragility and resilience. They remind humanity that complex systems, though vulnerable, can endure when balance is maintained. Whether these vibrant ecosystems survive the coming century depends on our collective capacity to act—not only as beneficiaries of nature’s beauty but as its stewards.

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3️⃣ ETS-Style Questions (12문항)
1. What makes coral reefs exceptionally productive ecosystems?
A. Their large geographic area
B. The symbiotic relationship between coral polyps and algae ✅
C. Their proximity to deep-sea vents
D. The abundance of nutrients in tropical waters
2. The word symbiosis in paragraph 2 is closest in meaning to:
A. Conflict
B. Mutual cooperation between species ✅
C. Competition
D. Domination
3. What happens during coral bleaching?
A. Corals grow more rapidly.
B. Corals lose their algae and energy source. ✅
C. Coral skeletons strengthen.
D. Ocean acidity decreases.
4. The word resilience in paragraph 4 is closest in meaning to:
A. Weakness
B. Ability to recover from damage ✅
C. Instability
D. Permanence
5. According to paragraph 4, what is one major local threat to coral reefs?
A. Melting polar ice
B. Sedimentation from coastal development ✅
C. Rising ozone levels
D. Decline in salt concentration
6. What effect does ocean acidification have on corals?
A. It increases coral reproduction.
B. It reduces coral growth and weakens skeletons. ✅
C. It enhances photosynthesis in algae.
D. It improves reef biodiversity.
7. The word calcification refers to:
A. Coral bleaching
B. Coral reproduction
C. The process of building calcium carbonate skeletons ✅
D. The breakdown of nutrients
8. According to paragraph 6, how do some coral species adapt to warming?
A. By eliminating symbiotic algae
B. By associating with more heat-tolerant algae strains ✅
C. By migrating to polluted waters
D. By ceasing reproduction
9. What is one ecosystem service coral reefs provide to humans?
A. Coastal protection from wave energy ✅
B. Increased desert rainfall
C. Soil fertility
D. Oil production
10. The word mitigation in paragraph 8 most nearly means:
A. Reduction or lessening of harmful effects ✅
B. Acceleration
C. Ignorance
D. Elimination
11. According to paragraph 9, what is essential for preserving coral reefs?
A. Global reduction of greenhouse gas emissions ✅
B. Increased urbanization
C. Deep-sea mining
D. Fish farming near reefs
12. Which of the following best expresses the main idea of the passage?
A. Coral reefs are disappearing due to natural cycles.
B. Coral reefs are vital yet vulnerable ecosystems requiring urgent protection from human-induced stress. ✅
C. Coral reefs can survive without algae.
D. Coral reefs are less diverse than previously thought.

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4️⃣ Passage Translation (한국어 번역)

산호초 생태계

산호초는 지구에서 가장 생물 다양성이 풍부하고 복잡한 생태계 중 하나다. “바다의 열대우림”이라 불리는 산호초는 바다 면적의 1% 미만을 차지하지만, 전체 해양 생물의 4분의 1이 이곳에 서식한다. 이러한 높은 생산성은 수백만 년에 걸쳐 진화한 정교한 생물학적 균형 덕분이다.

산호초의 중심에는 산호 폴립이라는 작은 동물이 있다. 이들은 석회질 물질을 분비해 단단한 골격을 만들며, 이 골격이 산호초 구조를 형성한다. 그러나 산호초 생태의 진짜 핵심은 폴립과 미세 조류(zooxanthellae) 간의 공생(symbiosis) 관계이다. 조류는 광합성(photosynthesis)을 통해 산호에 산소와 영양분을 제공하고, 산호는 조류에게 거처와 이산화탄소를 제공한다. 이 상호 관계 덕분에 산호초는 영양이 빈약한 열대 바다에서도 번성할 수 있다.

그러나 이 의존성은 산호초를 매우 취약하게 만든다. 바다 온도가 섭씨 1~2도만 올라가도 산호와 조류의 관계가 깨지며, 산호는 조류를 방출한다. 그 결과 산호의 색이 사라지는 백화(bleaching) 현상이 일어나고, 에너지원이 끊긴 산호는 죽게 된다.

이 외에도 산호초는 남획, 해안 개발로 인한 퇴적(sedimentation), 농업 오염으로 인한 조류 번식 등 다양한 지역적 위협에 직면한다. 이러한 요인들은 산호의 복원력(resilience) 을 약화시킨다.

또한, 해양 산성화(acidification) 는 대기 중 이산화탄소를 흡수하면서 pH를 낮춰 산호의 석회화(calcify) 과정을 방해한다. 결과적으로 산호의 성장이 느려지고 골격이 약해진다.

일부 산호는 고온에 강한 조류를 받아들이거나, 더 깊고 시원한 바다로 이동하며 적응한다. 인간은 산호 복원 프로젝트를 통해 조각을 양식하고 바다에 다시 옮기며 보존을 시도하고 있다.

산호초는 단지 아름다운 생태계가 아니라, 파도를 약화시켜 해안 침식을 막고 수산업과 관광업에 막대한 경제적 가치를 제공한다. 또한 의약품 개발의 유전자 자원이 되기도 한다.

산호초를 지키기 위해서는 온실가스 배출 감축과 오염 방지, 해양 보호구역 확대가 필수적이다. 지역사회가 주도하는 보호 활동 역시 큰 효과를 보인다.

결국 산호초는 ‘연약하지만 회복력 있는’ 생태계다. 균형이 유지된다면 살아남을 수 있다. 그러나 그들의 미래는 인간이 자연의 관리자로서 얼마나 책임감 있게 행동하느냐에 달려 있다.

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5️⃣ 문제 해석 + 정답 + 모든 보기 해설

Q1. 산호초의 높은 생산성의 원인은?
→ B. 산호와 조류의 공생 관계 ✅

Q2. symbiosis 의미
→ B. 서로 도움을 주는 생물 간 협력 관계 ✅

Q3. 백화(bleaching) 현상은?
→ B. 산호가 조류를 잃고 에너지 공급이 끊기는 현상 ✅

Q4. resilience 의미
→ B. 손상에서 회복하는 능력 ✅

Q5. 지역적 위협 중 하나는?
→ B. 해안 개발로 인한 퇴적물 증가 ✅

Q6. 해양 산성화의 영향은?
→ B. 산호 골격 약화 및 성장 둔화 ✅

Q7. calcification 의미
→ C. 석회질 골격 형성 과정 ✅

Q8. 산호의 적응 방식은?
→ B. 고온에 강한 조류와의 공생 전환 ✅

Q9. 인간에게 주는 생태적 서비스는?
→ A. 파도를 흡수해 해안 보호 ✅

Q10. mitigation 의미
→ A. 해로운 영향의 완화 ✅

Q11. 보호를 위해 필요한 것은?
→ A. 온실가스 감축 ✅

Q12. 본문의 주제는?
→ B. 인간 활동이 위협하는 산호초 생태계와 그 보존의 필요성 ✅

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