Chapter 25: History of Life on Earth
Synthesis of Organic Compounds on Early Earth
* The Earth probably formed about 4.6 billion years ago, and was bombarded with rocks and other material until about 3.9 billion years ago. * The Earth then cooled, allowing for the formation of oceans. Scientists hypothesize the general atmosphere, or at least some regions, were naturally reducing environments, meaning that they added electrons to compounds. * Activation energy provided by lightening or UV radiation may have been able to create organic compounds and amino acids, as demonstrated by a number of modern experiments. Abiotic Synthesis of Macromolecules
* Experiments have been done in which amino acid solutions in hot sand have formed polymers, but not true proteins. These polymers may have functioned as basic catalysts of some kind, however. Protobionts
* Cells have genetic material in the form of DNA and RNA, which they are also capable of replicating. Nothing like this has been generated spontaneously in lab experiments. * However, early structures called protobionts have had some of the capabilities associated with life. Experiments have spontaneously create protobionts, which are simple sphere of membrane that can perform simple metabolic and reproductive functions. * Note: phospholipids spontaneously form a bilayer, like the membrane that surrounds cells, so that part of the puzzle is easy to solve. Self-Replicating RNA and the Dawn of Natural Selection
* Simple RNA structures called ribozymes can carry out basic chemical reactions and are even capable of replicating themselves. * As ribozymes replicated themselves (with errors) protobionts could have developed internal collections of slightly different enzymes that formed a rudimentary metabolic system. The RNA in these early “cells” may have served as a template for the eventual creation of a DNA genome, which would have reduced the number of errors made during replication. The Fossil Record
* The fossil record gives a glimpse of life on Earth during different time periods and provides clues for evolutionary research. However, the fossil record also has significant gaps, but some are being filled by new discoveries. How Rocks and Fossils are Dated
* Fossils appear in individual sediment layers, which tell us the order that they were formed in but not an actual age in years. Scientists use radiometric dating to determine absolute ages. * Radiometric dating is based on the fact that some radioactive elements have predictable half-lives, or periods in which half of the substance will decay. If you know how much of a certain radioactive element an organism has when it died, such as carbon-14, you can determine its age by measuring the amount of carbon-14 remaining today. * Older fossils are harder to date, but you can at least guess based on the age of fossils in the surrounding layers. The Origin of New Groups of Organisms
* The presence of certain bones, different kinds of teeth and other characteristics can help researchers make inferences about what an animal may been like while it was alive. Changes between similar fossils of different time periods also show the pace of evolutionary change. The First Single-Celled Organisms
* Scientists have found fossilized stromolites that are thought to have lived 3.5 billion years ago – the earliest organisms discovered to date. Stromolites are mounds of prokaryotes that bind to their kin and other inorganic material. Photosynthesis and the Oxygen Revolution
* 2.7 billion years ago, there were probably cynobacteria in the ocean that used photosynthesis for energy and released oxygen in the process. The oxygen that these bacteria released would have eventually begun reacting with iron, and finally escaped into the atmosphere as a gas. * This buildup of oxygen actually killed many prokaryotes, and provided a strong selective force in favor of cells that could use oxygen in...
...THE HISTORY OF EARTH
Juni Haryanto (B1034131008)
Muhammad Ridwan (B1034131006)
Earth is the third planet in the solar system, earth has been created since 4.54 billion years ago. Every planet in the solar system it is only earth that we know have living creature inside because the condition of earth is the most possible place for living creature can live inside in the planet.
The first life creature live in earth is about 3.8 until 3.5 billion years ago. 3.7 billion years ago the biogenic is found as the evidence of living creature in the earth, the metasediment rocks discovered in Western Greenland. In 3.48 billion years ago microbial mat fossils has found in Western Australia.
After the first life creature live in the earth it is evolve continuously until now become the creature that we can se today including us one of the creature that evolve from the first time the life creature live in this earth. All of the creature now start from animal, plants until us is the evolution of earth creature.
A. Purpose of Study
1. To know the history of earth
2. To know what age of earth has been pass
The Theory of Forming of The Earth
There is many theory of...
...Life on Earth.
1. Analysis of the oldest sedimentary rocks provides evidence for the origin of life.
* Identify the relationship between the conditions on early Earth and the origin of organic molecules.
* Scientists estimate that the universe is 10-20 billion years old and arose as a big bang, which is still expanding the universe.
* The early Earth was very different from the Earth today and no oxygen was present. This means that there was no ozone layer exposing the Earth’s surface to ultraviolet radiation.
* There were large amounts of volcanic activity, heat, ash and dust and gases in the atmosphere.
* Violent electric storms were common.
* On our Earth, organic chemicals appear to have originated about 4 billion years ago.
* Early Earth, with an atmosphere of water vapour, hydrogen, methane and ammonia, provided an environment in which the production of organic molecules would be most likely formed in the lower atmosphere or the Earth’s surface.
* The organic compounds of water, carbohydrates, lipids, proteins and nucleic acids are composed of hydrogen (H), oxygen (O), carbon (C), nitrogen (N) and some other elements.
* The elements needed to create these organic compounds were already present in the atmosphere in early Earth.
* The lack of ozone layer, the frequent violent electric storms and...
...AP/IB 11 Biology
Origins of Life on Earth
There are multiple theories as to how life began on earth, beginning with the findings of various revolutionary scientists. This paper will discuss various scientists' theories and experiments as they strove to discover how life began, and the processes that might have occurred in order to develop and create the world we are now familiar with today.
Recent discovered functions of RNA have suggested that RNA provides a crucial framework in the evolution of the first cells, which may have been assembled from RNA comprised of nucleotides. Sidney W. Fox, a scientist at the University of Miami produced membrane-bound structures known as proteinoid microspheres. These microspheres can carry out some chemical reactions that resemble real living cells. They grow slowly and eventually bud off smaller microspheres. They're not living cells, but they are key in determining the kinds of processes that could have given rise to “self-sustaining protein entities”. It has even been hypothesized that comets and meteorites containing carbonaceous material hit the Earth with great force, and may have been a source of organic compounds such as lipid-like materials. David W. Deamer at the University of California and his co-workers extracted these organic materials from the carbon containing meteorites. Inevitably, some of the molecules assembled into...
...Beginning of Life on Earth
a) What is one of the suggestions for the beginning of life on Earth? What is the problem with this idea?
The article states that suggestions have been made that germs of life may have made their way to Earth from outer space. This may have occurred due to comet dust resting on the Earth's surface. Another theory proposed by Francis Crick states a spaceship sent out by a distant civilisation may have contained the first signs of life. The issue with these ideas is that no evidence has been obtained in support of these proposals, nor is there a reason to support these theories anymore due to substantial evidence that life did in fact start on the Earth itself.
b) What similarity existed between Urey-Miller's experiment and the Murchison meteorite?
The similarity that existed between Urey-Miller's experiment and the Murchison meteorite is the presence of similar amino acids in the same relative proportions. The Urey-Miller experiment aimed to determine how lightning could have possibly affected the atmosphere of the primitive Earth. The results showed that over just a few days, a variety of amino acids had formed from carbon methane subjected to electrical discharges. It is these same amino acids obtained via the Urey-Miller experiment that have been discovered in the Murchison meteorite. This...
Life on Earth
1. Analysis of the oldest sedimentary rocks provides evidence for the origin of life.
Identify the relationship between the conditions on early Earth and the origin of organic molecules.
- Conditions of early Earth:
Massive oceans existed
Only small landmasses above the surface of the water
No ozone layer
Large amounts of radiation reached the Earth
No free oxygen in the air
Large amounts of volcanic activity; heat, ash, dust and gases into atmosphere
Violent electric storms common
Atmosphere contained some water vapour (H2O), hydrogen (H2), hydrogen cyanide (HCN), a lot of carbon dioxide (CO2), nitrogen (N2), possibly ammonia (NH3) and methane (CH4).
- The chemicals of life are contained within the following basic organic compounds:
water, carbohydrates, lipids, proteins, and nucleic acids.
- These compounds are made up of hydrogen (H), oxygen (O), carbon (C), nitrogen
(N) and some other common elements.
- The elements needed to create the basic organic compounds were already present in the atmosphere; i.e., H, O, C and N were already there.
- The lack of an ozone layer, the frequent violent electric storms, and the volcanic activity of early Earth could have provided the energy for molecules to be formed.
Discuss the implications of the existence of organic molecules in the cosmos for the origin of...
...Paper - I
1. Sources: Archaeological sources:Exploration, excavation, epigraphy, numismatics, monuments Literary sources: Indigenous: Primary and secondary; poetry, scientific literature, literature, literature in regional languages, religious literature. Foreign accounts: Greek, Chinese and Arab writers.
2. Pre-history and Proto-history: Geographical factors; hunting and gathering (paleolithic and mesolithic); Beginning of agriculture (neolithic and chalcolithic).
3. Indus Valley Civilization: Origin, date, extent, characteristics, decline, survival and significance, art and architecture.
4. Megalithic Cultures: Distribution of pastoral and farming cultures outside the Indus, Development of community life, Settlements, Development of agriculture, Crafts, Pottery, and Iron industry.
5. Aryans and Vedic Period: Expansions of Aryans in India. Vedic Period: Religious and philosophic literature; Transformation from Rig Vedic period to the later Vedic period; Political, social and economical life; Significance of the Vedic Age; Evolution of Monarchy and Varna system.
6. Period of Mahajanapadas: Formation of States (Mahajanapada): Republics and monarchies; Rise of urban centres; Trade routes; Economic growth; Introduction of coinage; Spread of Jainism and Buddhism; Rise of Magadha and Nandas. Iranian and Macedonian invasions and their impact.
7. Mauryan Empire: Foundation of the Mauryan Empire, Chandragupta,...
Academic Standard 8-2
8-2.1 Explain how biological adaptations of populations enhance their survival in a particular environment
There are variations among species of similar populations. Organisms of a species differ from one another in many of their traits. A trait that helps an organism survive and reproduce is an adaptation. Species in a particular environment that are better adapted to living conditions there and are therefore able to meet their survival needs are more likely to survive and reproduce offspring with those traits.
Natural selection is the process that explains this survival and shows how species can change over time.
8-2.2 Summarize how scientists study Earth’s past environment and diverse life-forms by examining different types of fossils (including molds, casts, petrified fossils, preserved and carbonized remains of plants and animals, and trace fossils).
Mold fossil – forms when sediments bury an organism and the sediments change into rock, the organism decays leaving a cavity in the shape of the organism.
Petrified fossils – form when minerals soak into the buried remains, replacing the remains, and changing them into rock.
Preserved fossils – forms when entire organisms or parts of organisms are trapped in ice, tar or amber and are prevented from decaying.
Carbonized fossil – forms when organisms or parts, like leaves, stems, flowers, or fish, are pressed...
...Earth’s History and the Mesozoic Era
Earth’s history began about 4 billion years ago. The atmosphere contained almost no oxygen, and would have been toxic to humans, and most other modern life. Since then Earth has been a part of very important events, such as the formation of the solar system, which formed from a large, rotating cloud of dust, and gas called a solar nebula. Earth has also had other significant events like the formation of the moon, the creation of oceans, the origin of life, and the first continents. It has also been through many eons, starting with the Hadean eon about 4.5 billion years ago, followed by the Achaean eon about 3.8 billion years ago, and both are a part of the super eon Precambrian. All eons are organized on the Geologic Time Scale.
After the Achaean eon ended the Proterozoic eon began about 2.5 billion years ago. This eon included the oxygen revolution, which made a development in life. Life developed into eukaryotes, which were organisms whose cells contain complex structures enclosed within membranes. These cells have a nucleus with which genetic material is carried. During this eon there were severe ice ages. In the early Proterozoic eon the Earth cooled dramatically, and some scientists say that the Earth experienced ice ages so severe, that it was once completely frozen. This hypothesis is...