Okuma AnlamaSoru #9359
Deep-Sea Hydrothermal Vents and the Origins of Life
Until the late 1970s, marine biologists operated under the foundational assumption that all life on Earth fundamentally depended on photosynthetic energy derived from solar radiation. That paradigm shattered in 1977 when the deep-sea research submersible Alvin discovered hydrothermal vents along the Galápagos Rift, two and a half kilometers beneath the ocean surface. Here, superheated water reaching temperatures above 400°C spews from mineral chimneys known as "black smokers," rich in hydrogen sulfide and dissolved metals. In this perpetual abyss of utter darkness and crushing pressure, scientists discovered flourishing ecosystems teeming with giant tube worms, blind shrimp, and pale crabs. Instead of photosynthesis, the foundation of this thriving food web is chemosynthesis, driven by extremophile bacteria that oxidize toxic hydrogen sulfide to produce organic carbon. Many astrobiologists now hypothesize that life on Earth may have originated around such alkaline vents, and that analogous chemosynthetic ecosystems might exist today in the subsurface ice-covered oceans of Europa and Enceladus. What process fuels the primary biological production at hydrothermal vents?
- A)Anaerobic fermentation of dead organic debris drifting down from surface fisheries
- B)Photosynthesis performed by deep-sea kelp and symbiotic green algae
- C)Thermal absorption of geothermal radiation by giant predatory crabs
- D)Chemosynthesis carried out by bacteria that oxidize hydrogen sulfide
- E)Nuclear decay of radioactive basalt rocks beneath the oceanic lithosphere
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Doğru cevap: D) Chemosynthesis carried out by bacteria that oxidize hydrogen sulfide
Çözüm: Metinde besin zincirinin temelinin fotosentez yerine, toksik hidrojen sülfürü oksitleyerek organik karbon üreten bakterilerin kemosentezi (chemosynthesis) olduğu açıkça belirtilmiştir. Doğru cevap D'dir.