Use and Disuse of Organs: Continuous use of organs makes them more efficient and leads to their better development. Chemical evolution describes chemical changes on the primitive Earth that gave rise to the first forms of life. Moist clothes with grains after 20-21 days found young of rats. The fossils analyzed about 4 fit tall, slight raised of nose bone, development of forehead, etc. 2. 1. March 8, 2021. Similarly their came many scientist who discovered human fossils and wrote books in different ways. The fossils of this man were recovered by Anthropologist Mac. This is the most accepted theory on origin of life on earth. In this type the organic parts of body gets partly or completely replaced by mineral deposits, the replacement of organic parts by minerals deposits is called petrifaction. As a result first primitive living solution was developed at the sea bed. 3.Evidence from paleontological or fossil research character. Bipedal locomotion in man leaves the arms and hand free for carrying or doing things, the movable joints of arms, wrists, hands and fingers afford a great deal of versatility and the forelimbs can be used with great dexterity for handling tools. RNA world. Inheritance of acquired character: The character acquired during the lifetime of an individual are transmitted to its offspring. First theory to explain about origin of new species in most simple manner which anyone can understood. Darwinian Finches, Australian Marsupials. 2. c)Instead of survival of the fittest in man only arrival becomes most fitted. But the feet of man act as a platform and are suitable for palntigrade (walking on the soles of feet) type of locomotion. In general evolution is a dynamic process in which gradual change of body morphology takes place, after long period of time convert into more and more complex animal. Mar 04, 2021 - Evolution - Class 12, Biology | EduRev Notes is made by best teachers of Class 12. Ex. Charles Robert Darwin, an English naturalist, geologist, and biologist, is well known for his theory of evolution and the process of natural selection. The retina in the eye of man is provided with cone cells which perceive different colors. The haematic crystal of man and monkey looks very similar but differs with the horse and donkey or cow which also shows the similar common ancestor. After the selection by the nature ready for evolution of next animal. The condensed liquid was collected in the resultant bottle and analysed in the lab. 4. The universe is about 20 billion years old. On the basis of the fossil character some of the ape man is as follows: The fossil analyzed following characters; Almost walked by bipedal locomotion, nose almost flat, forehead flat, arrangement of teeth in the jaws are similar, possess arched palate, cranial capacity varies between 400- 600cc etc. The thumb of ape is short. Then, let free for few days. It helps to understand the way of evolution. Some the fossils are as follows; 1. It is believed that in human body, there are more than 200 vestigeal organs organs which showed the origin of man from different characters. 3. Due to continuous running habit limbs of the modern horse. On the basis of structure of genes of man and gorilla looks very much similar therefore must have the common ancestor. Biological evolution:  Mutation theory: The concept of mutation is given by scientist Hugo De Vries. After the view of Pasteur, this theory was totally discarded. The gene pool may be changed by, mutation, hybridization and natural selection. Impression: These are formed by the organisms or the parts of the organism come in contact with soft clay. He gave the theory of evolution, which is known as ‘Darwin’s theory of natural selection’ and also published a book, on “Origin of Species by Natural Selection”. The earth was formed about 4.5 billion years ago. The. Organisms which are better fit in an environment leave more progeny than others. These experiments proved the hypothesis of Oparin and Haldane. f) Divergent evolution: Evolution from the common ancestor but looks different in the morphological character. No mentioning about mutation because without mutation origin of new species never takes place i.e. For e.g. 1.Animals are highly fertile yet their totalnumber almost remains constant. Class 12 Biology Chapter 7 NCERT Solutions Q8.Describe one example of adaptive radiation. Although the reproductive rate is very high but in the nature population almost remain to be constant due to various factors. According to Lamarck, the short neck giraffe had the neck length 35cm and was feed upon the grasses. Only, originate from the pre-existing. Please keep a pen and paper ready for rough work but keep your books away. The solution was boiled for hours and hours. 5. Darwin proposed the concept of natural selection. Evolution is a process that results in heritable changes in population spread over many generations leading to diversity of organisms on earth. The first living things on Earth were prokaryotes with a type of cell similar to present-day bacteria. 6. Their bodies were shorter and stockier than ours, another adaptation to living in cold environments. Therefore, it can be said that ontogeny follows phylogeny. The evolution of life on earth, different changes in flora and fauna around earth that co-exist along with human beings also forms parts of evolution. They believed that it came from somewhere else in outer space and they named this phenomenon‘panspermia’. Hence having similar characters in the origin showed that all the vertebrates might have the common origin in the beginning. RNA, protein, polysaccharides. With the help of homologous organs of the animals can trace out the common ancestor. As the time passed gradually temperature decreases on the surface. This view could not explain the development of new animals or plants as well as growth of population. 1. Evolution is a branch of science deals with the unfolding of new and complex species from simple species. Later theory was supported by the scientist Spallanzeni and Pasteur. 3. For eg; c)Vestigeal organs: They are those organs which were functional in the past but these days became totally non- functional. Evolution Questions And Answers Class 12 Q9. Increase in the numbers of the animals population automatically increases competition in between inters specific and intra specific animals. These gases may have consisted of hydrogen (H2), water vapor, methane (CH4) , and carbon oxides. Therefore birds are also called glorified reptiles. The jaws and nose are smaller than those of gorilla. Darwin proposed the concept of survival of the fittest. This theory was developed when gene was discovered in 1901 by American Scientist Margon, Shutton, etc. 2. Can we call human evolution as adaptive radiation? If all the generation of the housefly continue their life cycle then in the near future world will be ruled by only housefly which is not happened yet. There are different plants and the animals which evolve in different ways in different habit, habitat or adaption. Panspermia is a hypothesis which says that life came from outside the earth, i.e. Evidence from physiology or bio-chemistry: The bio-chemical natures of the cells of the animal are very similar to each other. Prokaryote fossils have been found in 3.4-million-year-old rock in the southern part of Africa, and in even older rocksin Australia, including some that appear to be photosynthetic. CBSE Ncert Notes for Class 12 Biology Evolution. 1. The common character of the latest Pre historic man is as follows; 2.Development of nasal bone, forehead increases the cranial capacity of bone, bipedal locomotion, more intelligent, discovered different metal hunting tools, discovery of fires, know how to cook, lived in families, development of communicating ways, used animal skin as cloth , etc. 3. b) Formation of primitive life: In this stage protobionts developed the ability to reproduce and pass genetic information from one generation to the next. E.g. ; Herdmania or Ascidian. Blood sera or serum constitute plasma and corpuscles. This document is highly rated by Class 12 students and has been viewed 27376 times. He also found extra life development only in the jars without coverings. Anotralpethius African: Antrophologist Prosf Dart in 1924 discovered fossils of child from Australia and later from Africa. They proposed that formation of life was preceded by chemical evolution. Isotope ratios: carbon-12 to carbon-13 abundance is affected by metabolism in living things. In that period, Pasture experimentally proved that origin of life takes place from pre- existing life. When did life begin? 4.Evidence from physiology or bio-chemistry. View and Download PowerPoint Presentations on Evolution For Class 12 Cbse Science PPT. From that voyage he has collected many animal species. After the extinction of Cro-Magnon man came into existence man of today or modern man Homosapienswith more developed character such as; site of intelligence increased although cranial capacity slightly reduced to 1500-1550cc, developed various communicating ways or languages, enter into the age of aluminum age, discovered many technologies in the various fields, completely erect body, etc. The earth was covered with water vapor, methane, carbon dioxide and ammonia. Peking man, extinct hominin of the species Homo erectus, known from fossils found at Zhoukoudian near Beijing. There are many fossils of the pre historic men. Temperature believed between 3000-4000⁰C and was surrounded by primitive atmosphere. In the covered jar, he didn’t find any extra life but found in the jars having no coverings. Origin of Life 3. ©Copyright 2014 - 2021 Khulla Kitab Edutech Pvt. 1. extinct Jurrasic reptile or bird Archeopteryx is the best example of it. The UV rays from the sun split water into hydrogen and oxygen. b) Theory of special creation: This theory said that all the living beings existing these days were also present in the beginning simply remain in unknown. Natural Selection or Survival of the fittest (Spencer): Animals that can fight for struggle for existence possess best variation and heredity characters are said to be best of the best animal commonly called survival of the fittest. Encourage a discussion about the requirements for life and what "life" means in the In-Class Activity; Have students determine the viability of the Miller-Urey Experiment as a theory for the origin of life. e) Convergent evolution: Animals having similar functional characters but belongs to different category of animals. Thus he concluded that orifgin of life takes place from pre- existing life not from non-living things. • This theory has three connotations. In 1859, Darwin separately published the theory called theory of origin of species by natural selection. Because of adaptation body modifications takes place, such characters either uses continuously will gradually change into developing characters if not in use gradually disappear convert into vestigeal organs. Thus concludes in similar manner. enzyme tripase which digest protein in the amino acid is also present in the earthworm, cockroach, and frog and even in man. File Size: 136 kb: File Type: pdf: Download File. 3.Evidence from paleontological or fossil research character: Paleontogy deals with the study of fossils belonging to extinct animals. Nose further raise, cheek distinct, fore head distinct. In these manner modern man is also on the ways of changing thus probably in the future will changed into Homosapiensfutureless with further developed characters. d)Connective link(connecting link): Connecting link or missing link is a character shown by the animals belonging to two or more than two different groups. There are many theories about how life arose on earth. When the earth cooled down further, water vapor fell as rain; to form oceans. Diverse organic molecules were formed form inorganic constituents during the course of chemical evolution. Evolution is defined as slow and gradual process in which simple animal slowly changes into complex animal in relation to environment.Evolution can also define as descent with modification. 3. While he was studying in evening prime rose. Wanting of new organs by exercises is totally or manifestly false. 4 video links and lots of visuals. This big explosion threw out numerous pieces of cosmic material (nebulae) which slowly condensed and became organized slowly into groups of stars called galaxies. Darwin’s Theory of Evolution. The study of fossil provides most convening and direct evidence of evolution. Prior to the ape man including pre-historic man: After the ape men evolved man like pre historic man nearly from Pliocene period. 3. It helps to reconstruct or build the chain of evolution. 2. Evolution of Life Overview of Darwin's theory of evolution, a theory that describes the process through which populations of organisms change over time. Prior to the prehistoric man including modern man or man of today. The ending section of Molecular Evolution Class 12 Biology revision notes comprises all information related to the origin and evolution of human beings on Earth. Height ranges between 5 to 6 fit tall. For eg; wings of bat, bird, butterfly, etc. Life - Life - The origin of life: Perhaps the most fundamental and at the same time the least understood biological problem is the origin of life. The essence of Darwinian Theory about evolution is natural selection. The study of history of life forms on earth is called evolutionary biology. Similarly amylase and lipase are also present, help in the digestion of carbohydrate and fat. Similary on the basis of genetic characters the banding patterns in the gene of man and gorilla looks similar. by natural selection new species never evolved. Ans: Darwin’s finches of the Galapagos islands had common ancestors but now have different types of modified beaks according to their food habits. Compression: These fossils are formed as a result of burial of organisms. The reactions of gases resulted out of the permission of primitive living replicating solution coacervate. The teeth are essentially human though with some apelike features, such as large, partly overlapping canines. Hence for the evolution of any animals, mutation is most or mutation is a raw material for the origin of new species. Video transcript - [Voiceover] We have many videos on Khan Academy on things like evolution and natural selection. 2. Unaltered: In, these types, whole bodies of extinct organisms have been formed frozen in ice at the poles. From the naturally selected animals after long period of time changes in their morphological and anatomical characters due to various adaptations. Such organisms are selected by nature. Similarly Charles Darwin in 1871 published the book called Descent of Man. Among those animals having best variation will only continue life cycle as heredity, rest of all automatically dies. … In these manner slowly evolved more and more complex organisms such as poriferans, coelenterates, platyhelmenths and so on. They help to trace the facts correlated with their origin and evolution, relationship, increasing complexity etc. Later evolved prokaryotic organisms like bacteria and evolved eukaryotic organism like protozoans. In the beginning, the surface of the earth was too hot. As a result, there are several theories which offer their own explanation on the possible mechanism of origin of life. In the early origin of the earth was blanketed by primitive atmosphere or reducing atmosphere which constituted various gases like CO₂ , CO, SO₂, SO₃, N₂, NO₂, N₂O₅, H₂S, CH₄, H₂O, etc. 7. More intelligent than the prehistoric men. Isolation: Separation of organisms of a species into several groups or populations under geographical factors is supposed to be one of the most significant factors responsible for evolution. It was the size of the fox and possessed 4 limbs digits. Theory of Organic evolution : This is the latest and most scientific theory which said that in the beginning origin of life took place from simplest organic compounds but later from pre- existing life. ORIGIN OF LIFE. a. As a result after long time only those animals continue their life cycles that can fight for struggle for existence mainly for food and space. According to this theory said that in the beginning life was originated from the simplest organic compounds. The first cellular form of life possibly did not come into existence till about 2000 million years ago. Spontaneous Generation: Some thinkers believed that life came out of decaying and rotting matter; like straw, mud, etc. The Origin and Evolution of Life on Earth. 1. But no sign of extra life in the main solution. The origin of species by natural selection become failure because for the evolution of new species should change in the character of the genes. in the large intestine, Secrete enzyme cellulose for the digestion of cellulose or pectin or chloroplast, 3.Mictitating membrane or 3rd eye lid or plica-semilunaris. 9. After few days, he found certain extra life in the neck of the bottle having condensed liquid. Moulds exhibit the same external configurations of the organisms. Darwin is the second pioneer to give the theory about origin of species by natural selection. Conclusion: Origin of life took place from simplest organic compound in the beginning but not these days. 2.Vermiform appendex or short cylindrical, In between calcium and colon i.e. Origin of life 1. 3. 1. 3. This type of fossil found about 25000 years ago. The limb bones are indistinguishable from those of modern humans. Animals are better preserved as fossils as compared to plants. RNA, protein, polysaccharides. Revision Notes on Evolution (i) Ancient theories of origin of life: Various theories have been put forward to explain the phenomenon of origin of life. Genetic Drift: The variation in the gene frequency within population, simply because of chance rather than by natural selection is called genetic drift. CBSE Notes CBSE Notes Biology NCERT Solutions Biology. Such animals Darwin termed as naturally selected animals. a)Homologus organs: They are those organs having similar origin and anatomy but differ in morphology and functions. Dryopithecus and Ramapithecus- It helps to understand the structure of extinct animal. 2.Evidence from embryological character: Embryology deals with the development of embryos, every vertebrate embryo shows following common character. b) Not only struggle for existence other also continue life cycle like beggars. The fossil evidences reveal a gradual development of organisms with time. Miller observed the formation of amino acids. 6. According to this theory, the universe is a result of a massive explosion which occurred 20 billion years ago. Again from 1835-1855 travelled nearly for 20 years crossing over European seas and Indian ocean. b) Formation of Organic Compounds: In the second stage of chemical evolution, the simple organic molecules (such as amino acids) that formed and accumulated joined together into larger structures (such as proteins). The Big Bang Theory is the most accepted theory regarding the origin of the planet earth and the existence of different life forms on it. It helps to study about the habitat and behavior of the extinct organism. In 1809 published the theory called theory of inheritance of acquired character. Legs in man are 30% longer than the arms. The first cellular form of life possibly did not come into existence till … Flies, insect evolved from the decomposite materials. For eg: Hominoidea group like gorilla, Orangutan, Chimpanzee and Man. Alexander Oparin in 1923 and JBS Haldane in 1928, both the scientist supported theory of organism and published theory called Oparin Holdane theory. It is believed that our planet earth existed since 4.5 billion years back. He explains that the body of an organism is composed of two types of protoplasm, i.e. ; lengthening of the neck of giraffe. But their brains were just as large as ours and often larger - proportional to their brawnier bodies. To study human evolution in brief can be present as follows; 2. Since 3.2 billion years back. Human beings have achieved tremendous development in electronic fields, communication fields and space fields. Evolutionary biology is the study of history of life forms on earth. Effect of environment is true without which life cycle is impossible. b) Retrogressive evolution: Development of the adults in primitive forms. Oparin and Haldane proposed that the first form of life came from pre-existing non-living organic molecules; like RNA, protein, etc. Therefore, later the religious people published theory of special creation which said that all the living beings were created by god and goddess. Blog. Human Reproduction Welcome to Biology Observations in Science Learning About the Microscope Microscope Microscope Introduction Parts of the Microscope Carbon Based Molecules Cycles of Matter Energy Flow in Ecosystems Homostasis and the Human Body Chapter 2 Atoms Around Us Chapter 2 Chemical Bonds Science of Tie Dye Chapter 2.1 Properties of Water Chapter 2.4 Chemical Reactions … Animals are highly fertile, yet their total number remains constant: All the animals have high reproductive rate in their life cycle. It is believed that ape like animals were evolved during Miocene period and man like creature developed in the Pliocene period of Cenozoic era. 2. The major characters of theory are as follows; Each and every animals are directly or indirectly affect by the surroundings or environment with the change of the environment gradually animals also changes habit or adaptation. 2. Resultant solution was found the mixture of amino acid and pentose sugar which was also the basic component of coacervate solution. For e.g. If the blood of man and monkey mixed together with the blood of horse and donkey immediately agglutination takes place that is man and monkey must have close ancestor. This solution evolved first life cyanobacteria or blue green algae. 3. Observations by some others showed formation of sugars, nitrogenous bases, pigments and fats. The atmosphere was not present on early earth. These galaxies appear to be moving away from one another at a speed nearly equal … Scientists TH Huxley was the first who wrote book about the evolution of man in 1863. Reddi’s experiment: He collected dead snakes, meat and put into the several jar with or without coverings. As a result from those animals originate new species which is called origin of species. 4. In the French Science Journal Philpsophie Zoologique. c. Presence of pharyngeal gill slits for respiration. Origin of life: It is generally agreed that all life today evolved by common descent from a single primitive lifeform. The coacervate solution shows the composition of organic compound like amino acid, pentose sugar, fatty acid, nucleotides etc. The organism acquires certain new characters due to direct or indirect environmental effects during its own lifespan and these characters are called acquired. But Louis Pasteur disproved this theory by proving that life comes only from pre-existing life. Gene pool: A gene pool may be defined as the total variety of genes and alleles present in sexually reproducing population. Conditions on the Early Earth. After that he broke the neck of the bottle and again let free for few days. Panspermia: Early Greek thinkers thought that units of life (called spores) were transferred to different planets including earth. Some of the vestigial organs are as follows; Help in the movement of pinnae for the collection of sound. Various reactions took place in the primitive atmospheric gases in the presence of high voltage energy. 2. In the first 500 million years a dense atmosphere emerged from the vapor and gases that were expelled during degassing of the planet's interior. INTRODUCTION Several attempts have been made from time to time to explain the origin of life on earth. Thumbs are better developed. It is discovered by the Dutch anatomist in the early 1890s were the first known fossils of the species Homo erectus. Life appeared on earth about 4 billion years back. Origin of Life ,Evolution - Get topics notes, Online test, Video lectures, Doubts and Solutions for CBSE Class 12-science on TopperLearning. Darwin did not mention about vestigial organs which are found in the animals. A video to explain origin of life… 14. CBSE Class 12 Biology Revision Notes Chapter 7 Evolution. For eg; forelimb bones of the animals are humerous, Radio-ulna, carpels, metacarpels and phallenges. Later found extra life in the main solution which no doubt came from atmospheric air. Genetics deals with the study of genes which carry hereditary characters from generation to generation. Experiment by Miller and Urey: They created an atmosphere in laboratory; similar to what existed on the earth about 4 billion years ago. It is useful in the study of the external morphology. Theory of natural selection states that individuals that are less adapted to the environment are eliminated and selecting those better adapted by the nature. Theory of Lamarck or Lamarckism or Theory of inheritance of acquired characters: Jean Baptist De Lamarck (1744-1829) was a famous Botanist in that period has written many books and articles and also discovered many plants. There was, however, no evidence to support these claims.The early scientists and Greeks believed that life on earth never began on earth itself. ISC 12>ORIGIN AND EVOLUTION OF LIFE>1. 2. 8. Evolution Class 12 Notes are created by our panel of highly experienced teachers to help students grasp challenging concepts and thus prepare for exams effectively. c) Change in the characters of genes present in the chromosomes. Among these gases, most of the gases reacted with each other in presence of high energy which may be energy from lightening, energy from solar energy or sun, energy from radioactive element, energy from volcanic eruptions. This character was present in prehistoric embryos so can be called as Phylogeny characters and also found in present embryos, can be called as ontogeny characters. 2. Animals who could fight for struggle for existence only continue their life cycles. Thus, chemical evolution became an accepted theory of origin of life. There are a number of distinctive features of human species which make it different from his close relatives, the anthropoid apes (for example, gibbons, orangutan, gorilla and chimpanzee). The capacity of the human brain box is 100cc; in gorilla it is 510cc. 4. The stages of evolution of man are-1. a) Formation of Protobionts (Coacervates): The next step in chemical evolution suggests that polymers interacted with each other and organized into aggregates, known as protobionts. 4. This is the latest and most scientific theory which said that in the beginning origin of life took place from simplest organic compounds but later from pre- existing life. The development of body organs is only limit in their life time that is new inherited. Learn the concepts of Class 12 Biology Evolution with Videos and Stories. The RNA origin of life. Cast or moulds: These are formed when an organism get submerged in water containing lime. Neanderthals made and used a diverse set of sophisticated tools, controlled fire, lived in shelters, made and wore clothing, were skilled hunters of large animals and also ate plant foods, and occasionally made symbolic or ornamental objects. Variation whether somatic or genetic because only genetic variation are heredity. Similarly changed in median leaves and finally upon the leaves of tall trees. Practice: Origins of life on Earth. In the same period another young scientist Sir Alfred Wallace was also study about the different nature of beaks of birds in Malayan peninsula. Development of communication or language etc. Used animal skin as cloth, lived in colonies or in families. In 1858, Darwin and Wallace combinedly published book origin of species which became highest book sell in the world. Zinjan thropus: leaky in 1959 discovered fossils from Tanzania which analyzed about 5 fit tall, walked almost erect, more intelligent than the ape man, developed communicating ways as well as hunting tools. This is a 44 slide PowerPoint presentation that cover theories as to the origin of life (Oparin, Lerman, Miller + Urey, Fox) and takes students through an adventure back in time covering the geological time scale. For e.g. The human species walks erect on two feet (bipedal). Germplasm Theory: in 1886, August Weismann explains about this theory. Origin of earth and its atmosphere:Earth is believed to have formed about 5 billion years ago. Neo-Darwinism forwarded many important ideal to explain his theory. Evolution of Life • Several assumptions were to propose evolution of life of which the first was religious literature which tells us about the theory of special creation. He took swan necked bottle in which kept hay particles and added tap water. Overview • The formation of Earth • Pre-biotic chemistry (Miller-Urey exp.) The body size slightly increases with 3 digits in the limbs. Neanderthals are our closest extinct human relative. Prior to 3.5 billion years ago the atmosphere probably consisted of carbon dioxide (CO2), carbon monoxide (CO), water (H2O), nitrogen (N2), and hydrogen.The hydrosphere was formed 4 billion years ago from the condensation of water vapor, resulting in oceans of water in which sedimentation occurred. Due to lack of evidences this theory was also discarded. Similarly from the different parts recorded the fossils of the following pre-historic men; Java man, extinct hominin known from fossilremains found on the island of Java, Indonesia.

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