Day 51
Passage 51
Sentence 51
Day 52
Passage 52
Sentence 52
Day 53
Passage 53
Sentence 53
Day 54
Passage 54
Sentence 54
Day 55
Passage 55
Sentence 55
Day 56
Passage 56
Sentence 56
Day 57
Passage 57
Sentence 57
Day 58
Passage 58
Sentence 58
Day 59
Passage 59
Sentence 59
Day 60
Passage 60
Sentence 60
Day 61
Passage 61
Sentence 61
Day 62
Passage 62
Sentence 62
Day 63
Passage 63
Sentence 63
Day 64
Passage 64
Sentence64
Day 65
Passage 65
Sentence 40
Day 66
Passage 66
Sentence 66
Day 67
Passage 67
Sentence 67
Day 68
Passage 68
Sentence 68
Day 69
Passage 69
Sentence 69
Day 70
Passage 70
Sentence 70
Day 71
Passage 71
Sentence 71
Day 72
Passage 72
Sentence 72
Day 73
Passage 73
Sentence 73
Day 74
Passage 74
Sentence 74
Day 75
Passage 75
Sentence 75
內容試閱：
Origin of Life
There are many different theories concerning where the origin of life occurred. Some of these theories are more credible than others, yet all provide an interesting explanation for lifes beginnings.
One early explanation, known as the Materialistic Theory or Physico-chemical Theory, was proposed independently by two scientistsA.I.Oparin, a Russian scientist in 1923 and J.B.S Haldane, an English scientist in 1928. It states that the origin of life on earth is the result of a slow and gradual process of chemical evolution that probably occurred about 3.8 billion years ago. This theory was the precursor of another theory called abiogenesis, also known as spontaneous generation, which studies how life on Earth could have arisen from inanimate matter. It suggests that life began in water as a result of the combination of chemicals from the atmosphere and some form of energy to make amino acids, the building blocks of proteins, which would then evolve into all the species.
Essential to this spontaneous origin of life was the availability of organic molecules as building blocks. Already in 1922 Oparin had proposed that the early Earth had a reducing atmosphere comprised mainly of ammonia, methane, and large amounts of hydrogen. Later in 1953 , Stanley Miller successfully carried out the famous Miller-Urey experiment which showed that amino acids could be produced under a condition where a mixture of methane, hydrogen, ammonia and water is reacted in a spark discharge apparatus, the condition similar to those on the primitive Earth.〇1 The idea of spontaneous generation was popular almost till seventeenth century, supported by many scientists like Descartes, Galileo and Helmont.
Toward the end of the 19th century and the beginning of the 20th century, as scientists were learning about the genetic and biochemical complexity of the cell, confusion about the origin of life grew. One way around the problem was to say that life had never emerged, but
購物車/收銀台(0) | 在線留言板
| 付款方式
| 聯絡我們
| 運費計算
| 幫助中心 |
加入書簽
HOME
新書上架
