Passage
In 1991, five years after the disaster at the Chernobyl Nuclear Power Plant, scientists investigating the damaged reactor vessel made an unexpected discovery: dark, melanized fungi thriving on the highly radioactive walls. Subsequent research revealed that these species, such as *Cryptococcus neoformans*, did not merely tolerate the radiation but actively grew toward it, a phenomenon known as positive radiotropism. Researchers hypothesized that these organisms engage in "radiosynthesis," a process analogous to photosynthesis in plants. Melanin, the dark pigment found in human skin, plays a critical role in this adaptation. In radiotrophic fungi, melanin absorbs gamma radiation and converts it into chemical energy, which the fungi use to drive metabolic processes and accelerate growth. Scientists demonstrated this by exposing melanized and non-melanized strains of the same species to ionizing radiation; the melanized strains showed significantly increased biomass and cellular activity under irradiation, whereas the non-melanized strains did not. While photosynthesis relies on chlorophyll to capture visible light, radiosynthesis utilizes melanin to capture high-energy radiation. This discovery challenges the traditional assumption that ionizing radiation is purely destructive to biological systems, opening up potential applications in space exploration, bioremediation, and biotechnology.
Which statement best summarizes the main idea of the passage?
- AMelanin absorbs gamma radiation and enables melanized fungal strains to exhibit significantly increased biomass and cellular activity compared to non-melanized strains.
- The discovery of radiotrophic fungi reveals that some organisms can utilize melanin to convert ionizing radiation into chemical energy for growth, challenging traditional views on radiation's impact on life.Answer
- CPhotosynthesis and radiosynthesis are identical biological processes that demonstrate how life forms adapt to extreme environments on Earth and in space.
- DScientists have successfully engineered non-melanized fungal strains to survive in highly radioactive environments like the Chernobyl nuclear reactor.