short note on origin of life


Our earth belongs to the Solar system having nine stars called planets constantly rotating around a common Sun. The evidences come from comparative study of external and internal structure.

all organisms and has led to three large domains of life: Bacteria, Archaea, The study of universe or cosmos is called Cosmology. These are degenerate, non-functional and rudimentary organs to the possessor, while correspond to fully developed and functional organs of related organisms. Zealand.

This race is often aggressive and dominant in nature.
HIV, TMV); help in protein synthesis. Ichthyosaurs). Required fields are marked *, Copyright © 2016-20 Pmfias.com. The phenomenon of formation of new species from pre-existing ones is called speciation. The origin of life - Very Short Introductions ‘The origin of life’ hows that from the earliest days people have wondered about the origins of life. moons in our solar system. Angiotensin-II and Vasopressin or ADHare proteins formed of 8 and 9 amino acids respectively. For example, most people recognize that mule deer and white We know Notes The planet earth came into existence sometime between 4 and 5 billion years ago. differences among the organisms of today and those that existed years ago. of them are active today, they likely produced hot springs and geysers

(iv) Biogeographical evidences The species restricted to a region develop unique features. Agar: A homopolysaccharide of fructose, so is also called fructan. It is a modification of the original theory of Lamarck in order to make it more suitable to modern knowledge. that life began at least 3.5 billion years ago, because that is the age Origin And Evolution Of Life: Philosophers and scientists have been busy to solve the riddle as to how the universe and our earth were formed and how and when 'life' originated on earth.

[1996], Q2. its icy surface. The branch of life science for the study of 'Origin of life' and evolution of different forms of life on earth wa Colour of skin is red, light brown or yellow. Please correct me if I m wrong…. Condition of atmosphere was anaerobic. Eukaryotes developed around 1600 million years ago. We do not know the true reason. It was about 50 m in length…. Bushmenof Australia and Africa, Bhilsof India and Veddansof Srilanka are included in this group.

2. The same structure developed along different directions due to adaptations to different needs. Biochemical Evidences Every second, about 10 million molecules of ATP are formed from ADP and phosphate molecules and equal number of ATP molecules are hydrolyzed to provide energy for metabolic processes. Normally only those modification are transferred to next generation which influence germ cells or where somatic cells give rise to germ cells.

Kring and his colleagues have been investigating impact-generated Examples are These were probably single-cells. (iii) Theory of spontaneous generation states that life originated from decaying and rotting matter like straw, mud, etc. ancestors that share a common set of traits. ATPwas first discovered by Karl Lohmanin skeletal flight muscles of insects. Coacervates as pre-cells were formed due to aggregation of organic molecules. About 65 mya, the dinosaurs suddenly disappeared from the earth. II. To determine the origin of life, scientists are investigating the problem in several different ways. Since then, approximately 15 million different species of organisms have evolved. Land plants first appeared in Ordovician (420-500 million years) and silurian (400-420 million years) periods. 3. (e) The study showed that life forms varied over time and certain life forms are restricted to certain geological time-scale Hence, new forms of life have evolved at different times in the history of earth,

(v) This form of abiogenesis, i.e.

Darwinism is based on natural selection or survival of the fittest. And although none

This can be explained with the help of following processes: (a) Organs which are anatomically different but functionally similar are called analogous organs. In azoic era life was absent. Same of them are tail bone (coccyx), wisdom teeth, nictitating membrane, vermiform appendix, etc. They are not anatomically similar structures though they perform similar functions.

tail deer are more closely related than mule deer and grizzly bears. Scientists like Lemaitre(1931), Gamow(1948), Dicke(1964) etc. It is the evolution in which different structures evolve for same function and hence, have similarity. It believes in the selection of individuals on the basis of accumulation of variation. The universe expanded and hence, the temperature came down. The origin of life on Earth is a highly curious thing. one can begin to group and separate organisms based on their common (or The theory is silent about them though it believes in a continuous modification of organs in a particular direction. 1. of life have also been detected in slightly older rocks. The conditions on the earth that favoured chemical evolution were very high temperature, volcanic storms and reducing atmosphere that contained CH4,NH3, water vapour, etc.

Then came the theory of spontaneous generation of life durin… Another way of saying the same thing is that some organisms are better adapted to survive in an otherwise hostile environment. All rights reserved | Terms & Privacy | Amazon Affiliate Disclosure. It is the original theory given by Charles Darwin (1859) to explain the origin of new species. It is not known how this early life form evolved, but scientists think it was a natural process which happened about 3,900 million years ago. Complex molecules like sugars, nitrogen bases, pigments and fats were seen in the flask by other scientist. Bailey and David A. Kring. all rights reserved.

(b) Ernst Haeckel propounded The theory of recapitulation or Biogenetic law which states that an individual organism in its development (ontogeny) tends to repeat the stages passed through by its ancestors (phylogeny), i.e. For the same thing to happen in a fish or fowl would take million of years as life spans of these animals are in years. Evolution is a continuous process which moves in a direction governed by environment and appentency. The Origin of Life and Evidences of Evolution: (d) Homology is based on divergent evolution. These revealed hominid features leading to the belief that about 3-4 mya, man-like primates walked in eastern Africa. To determine Some of the bones among the bones discovered were different. supported the Big-Bang Hypothesiswhich explains that collision between these particles and antiparticles caused a tremendous explosion to form atoms of hydrogen. hydrothermal systems. Huge clusters of galaxies comprise the universe. Some scientists believe that the life came from outerspace.

Mammals originated in the Triassic period of Mesozoic era. The organs put to more use are believed to develop more while organs not used begin to degenerate. The theory considers appentency or desires on the part of animals an important force in the development of modifications. It has a. The universe is made up of matter and energy and it was formed about 10 to 13 billion years ago as a red hot, dense, rotating gaseous cloud of cosmic dust called Ylem or primaeval matter. and Australia.
First organisms were blue-green algae (cyanobacteria developed near sea shore). The origin of life is a result of a supernatural event—that is, one irretrievably beyond the descriptive powers of physics, chemistry, and other science. (ii) These molecules were like RNA, protein and polysaccharides. (d) A study of fossils in different sedimentary layers indicates the geological period in which they existed. Homeostasis is found in all the living organisms. (e) Life appeared 500 million (about 4 billion years back) years after the formation of earth. Arrhenius in 1908 proposed the theory of Panspermea or Interplanetary theory. (iii) Theory of panspermia/cosmozoic theory, given by early Greek thinkers states that the spores or panspermia came from outer space and developed into living forms. (i) Theory of special creation states that God created life by his divine act of creation. From the original seed-eating features, many other forms with altered beaks arose, enabling them to become insectivorous and vegetarian finches. Source | Credits | Picture Credits: NCERT General Science Origin Of Life on Earth The universe is very old - almost 13 billion years old. In all cases, Download Revision Notes as PDF. When reptiles came down mammals took over this earth. The debate of when the earth became habitable is discussed along with traces of early life and the biochemical theory for the origin of life, including the Oparin–Haldane model. Evolution is a process that results in heritable changes in population spread over many generations leading to diversity of organisms on earth. (b) Analogy refers to a situation exactly opposite to homology. Above) Examples of modern There was, however, no evidence to support these claims.The early scientists and Greeks believed that life on earth never began on earth itself. Chemical traces Variations appear due to change in genetic make up. (b) UV rays from the sun broke up water molecule into hydrogen and oxygen and lighter hydrogen escaped. Homeostasis also operates at all levels of ecological hierarchy (e.g. Sir The Origin of Life and Evidences of Evolution: 1. levels. Dinosaurs and cycads originated in the Jurassic period.

(c) Some organisms appear similar to modern organisms. lava. (a) It is very old-almost 20 billion years ago. Above Right) 3.5 billion year old sedimentary chert. They have fair or brown coloured skin, long or broard head, thin nose and wavy hair on head. Source | Credits | Picture Credits: NCERT General Science. (1999, 2006), and Orgel (1998). habitat for that life to evolve. All rights reserved |, Q1. Some say climatic changes killed them. The first non-cellular forms of life could have originated 3 billion years back. (v) Embryological evidences Study of comparative embryology shows common patterns of development. Small sized reptiles of that era still exist today. The theory of Biochemical origin of the life was proposed by Oparin in 1923 and supported by Haldane in 1928. They represent extinct organisms like dinosaurs. (iv) Theory of chemical evolution or Oparin-Haldane theory states that life originated from pre-existing non-living organic molecules and that formation of life was preceded by chemical evolution. Second law of thermodynamicsis also called law of Entropy.

(i) Wings of insect, bird and bat. There are 3,000 different types of proteins in Escherichia colibacterium, and about 100,000 different types of proteins in the human being. A change in the medium composition would bring out only that part of the population (say B) that can survive under the new conditions. I. The origin On the basis of the order of the distance from the sun these planets include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto while moon is a satellite of earth. Theories of Origin of Life.

Concept and content by David A. Kring. (d) The Big Bang theory states that a huge explosion occurred, the universe expanded, temperature came down and hydrogen and helium were formed later. This web site is based on information originally created for the NASA/UA Space Imagery Center’s Impact Cratering Series. Normal glucose level is 60-100 mg/100 dlof blood.

CBSE Class 12 Biology Revision Notes Chapter 7 Evolution. They are usually a mix of solidified volcanic lavas

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