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In what way did the scientists suppose alien life might be thriving? [br] [orig
In what way did the scientists suppose alien life might be thriving? [br] [orig
游客
2023-12-24
42
管理
问题
In what way did the scientists suppose alien life might be thriving? [br]
Alien life might be purple. That’s the conclusion of a new research paper that suggests that the first life on Earth might have a lavender hue. In the International Journal of Astrobiology, microbiologist Shiladitya DasSarma of the University of Maryland School of Medicine and postdoctoral researcher Edward Schwieterman at the University of California, Riverside, argue that before green plants started harnessing the power of the sun for energy, tiny purple organisms figured out a way to do the same.
"Alien life could be thriving in the same way," DasSarma told Live Science. He suggested that astronomers have discovered thousands of new extrasolar planets recently and in addition to examining substances such as water and air, they are developing the capacity to see surface biosignatures in the light reflected from these planets. There are already ways to detect green life from space, he said, but scientists might need to start looking for purple, too.
The idea that the early Earth was purple is not new, DasSarma and his colleagues advanced the theory in 2007. The thinking goes like this: Plants and photosynthesizing algae use chlorophyll to absorb energy from the sun, but they don’t absorb green light. That’s odd, because green light is energy-rich. Perhaps, DasSarma and his colleagues reasoned, something else was already using that part of the spectrum when chlorophyll photo synthesizers evolved.
That "something else" would be simple organisms that captured solar energy with a molecule called retinal. Retinal pigments absorb green light best. They’re not as efficient as chlorophylls in capturing solar energy, but they are simpler, the researchers wrote in their new paper.
Retinal light-harvesting is still widespread today among bacteria and the single-celled organisms called Archaea. These purple organisms have been discovered everywhere from the oceans to the Antarctic Dry Valley to the surfaces of leaves, Schwieterman told Live Science. Retinal pigments are also found in the visual system of more complex animals.
Regardless of whether the first life on Earth was purple, it’s clear that lavender life suits some organisms just fine, Schwieterman and DasSarma argue in their new paper. That means that alien life could be using the same strategy. And if alien life is using retinal pigments to capture energy, astrobiologists will find them only by looking for particular light signatures, they wrote.
选项
A、They can capture green light.
B、They can absorb the energy of light.
C、They can capture sun light efficiently.
D、They can generate energy.
答案
B
解析
事实细节的找寻与判断。根据原文“use chlorophyll to absorb energy from the sun, but they don’t absorb green light”可知叶绿素不吸收绿光,选项A错误。“They’re not as efficient as chlorophylls in capturing solar energy”是比较叶绿素和视黄醛捕获光能的能效,无法以此推测它们都能高效捕获太阳能,选项C错误。文章没有涉及这两种物质能制造能量,选项D错误。根据原文,叶绿素和视黄醛都能吸收光能,选项B正确。抓住关键词,排除干扰项。
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