LIFE
1. HOW DID LIFE BEGIN?
Ans: Scientific experiments in the 1950 s showed how lightning flashes might create amino acids, the basic chemicals of life, from the waters and gases of the early Earth. But no one knows how these chemicals joined up to become “self replicating -that is, able to make copies of themselves. This is the key to life, which remains a mystery. However, the first life forms were probably tiny bacteria called Archebacteria, which thrive in very hot, chemically rich places.
2. WHAT IS LIFE MADE OF?
Ans: Life is based on complex compounds of the element carbon, known as organic chemicals. Carbon compounds called amino acids link up to form proteins, and proteins form the complex chemicals that build and maintain living cells.
3. WHERE DID THE MATERIALS OF LIFE COME FROM?
Ans: It used to be thought that organic chemicals all originated on Earth, but traces of all kinds of organic chemicals
have be on detected in giant molecular clouds, including formaldehyde, alcohol, and also acetaldehyde, one of the
components of amino acids.
4. WHERE DID LIFE COME FROM?
Ans: Most scientists think life on Earth began on Earth,in the oceans or in volcanic pools. But some think the Earth was seeded by micro- organisms from space.
5. ARE THERE ANY OTHER PLANETS LIKE EARTH?
Ans: There is no other planet like Earth anywhere in the solar system. Recently, though. planets have been detected circling other stars in neighbouring galaxies. But they are too far away for us to know anything about them at all.
6. WHAT DOES AN ALIEN LOOK LIKE?
Ans: At the moment, the only aliens we are likely to encounter are very, very small and look like viruses.
7. HOW ARE WE LOOKING FOR EXTRA-TERRESTRIAL LIFE?
Ans: Since possible fossils of microscopic life were found in Martian meteorite found on Earth in 1996, scientists have hunted for other signs of organisms in rocks from space. Robotic probes are currently searching for signs of life on Mars.
8. IS THERE LIFE ON OTHER PLANETS?
Ans: Organic chemicals are widespread, and the chances are that in such a large universe there are many planets, like Earth, suitable for nurturing life. But no one knows if life arose on Earth by a fantastic and unique chain of chance events, or whether it is fairly likely to happen given the right conditions.
9. WHY IS THE UNIVERSE LIKE IT IS?
Ans: The amazing chance that life exists on Earth has made some scientists wonder if only a universe like ours could contain intelligent life. This is called the weak anthropic principle. Some go further and say that the universe is constructed in such a way that intelligent life must develop at some stage. This is called the strong anthropic principle.
10. WHAT IS DNA?
Ans: Deoxyribonucleic acid, the most remarkable chemical in the universe, is the tiny molecule on which all life is based. It is shaped a bit like a long rope ladder, with two strands twisted together in a spiral, inked by “rungs” of four different chemical bases. The order of these bases is a chemical code that provides all the instructions needed for life.
11. WHAT IS SETI ?
Ans: SETI is the Search for Extra-Terrestrial Intelligence project, designed to continually scan radio signals from space and pick up any signs of intelligence. lt looks for signals that have a pattern, but are not completely regular, like those from pulsating stars.
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