RBSE Class 12 Biology Notes Chapter 7 Evolution

These comprehensive RBSE Class 12 Biology Notes Chapter 7 Evolution will give a brief overview of all the concepts.

RBSE Class 12 Biology Chapter 7 Notes Evolution

→ Evolutionary biology is the study of history of life on the earth.

→ Evolution is a process that results in inheritable changes in the genotype which spread over many generations, leading to the diversity of organisms on the earth. In simple words, evolution is the sequence of gradual change from simple life forms to complex life forms over millions of years.

→ The universe is about 20 million year old. It contains huge galaxies. Galaxies contain stars, cloud of gaser and dust.

→ The origin of universe is explained by Big Bang Theory given by Abbe Lemeitre in 1931.

→ It is considered that our earth along with other planets of the solar system, originated from cooler and less denser peripheral part of a solar nebula. The period of Earth’s origin is supposed to be about 4.5 million years ago.

→ Various theories of origin of life on the earth were given by different thinkers and scientists. These theories are theory of special creation ; Theory of catastrophism, Theory of cosmoozoic creation. Theory of Abiogenesis, Theory of biogenesis. But most accepted theory, which fovoured to origin of life is biogenesis theory.

→ Theory of chemical evolution or oparin-Haldane theory states that life originated from pre- existing non-living organic molecules and that the formation of life was preceded by chemical evolution.

→ In 1953 Stanley Miller and Horold Urey experimentally proved the formation of simple organic compounds from simple compounds under reducing conditions.

→ First non-cellula life forms originated 3 billion years ago. These molecules were like RNA, protein and polysaccharide inside a self-replicating metabolic capsule which later reproduced its molecules.

→ The actual origin of life form the non-living chemical compounds involved two main stages:

1. From coacervates to the first primitive living system, called proto cells or protobionts.
2. From protobionts to first living cell.

→ Many types of evidence support the doctrine of organic evolution. These are: Palacontolagical, morphological and anatomical, embryological, biogeographical, physiological, texonomical etc.

→ The Fossils are the remains or impressions of the ancient organisms preserved by natural means in some medium i.e. rocks or otherwise.

→ the transitional fossil organisms which possess character of two different group of present day living forms are called missing links.

→ The organ with same structural design and origin but different functions are called homologous organs. Organs which are anatomically different but functionally similar are called analogous organs.

→ Various Theories have been put forward to explain the mode of evolution. Some of them are: Darwin's theory of natural selection, Lamarck’s theory of inheritance of Acquired characters, Hugo de Vries theory of Mutation, etc. 

→ Speciation is the origin and evolution of new species, speciation is of two types: Allopatric speciation and sympatric speciation.

→ The time period from the origin of earth to till dai has been divided into 6 eras and 12 periods according the geographic time scale.

→ Adaptive radiation is an evolutionary process in which an ancestral stock give rise to new species that are adapted to new habitats and new ways of life.

→ Gregory (1951) and corbert (1955) proposed that monkey-apes were the common ancestor of old world monkey, apes and men.

→ Modern or present day man evolved from cro-magnon man about 25000 years ago in Africa.

→ Abiogenes: Origin of living things from non-living substances.

→ Anthropology: Branch dealing with the study of human evolution.

→ Species: A group of living organisms consisting of similar individuals capable to interbreeding.

→ Speciation: Origin of new species from Pre-existing species.

→ Simians: Advanced primates including monkeys, apes and humans.

→ Ontogeny: Development of an individual in known as ontogeny.

→ Phylogeny: Evolutionary history of an individual.

→ Palenotology:    Study of fossils, is called paleontology.

→ Eobiont: Cell- like bodies with division power.

→ Fossil: Remains or impressions of hard part of extinct organisms, preserved in sedimentary rocks or other media.

→ Genetic drift: Random change in allele frequencies due to chance fluctuations, called genetic driff.

→ Atavism: Reappearance or refunctioning of lost or vestigial organs is called atavism.

→ Mass Extinction: Rapid and large scale destruction of living organisms e.g. extinction of dinosaurs.

→ Coacervates: Large colloidal cell - like aggregates of complex organic compounds are called coacervates.

→ Acquired Characters: Changes from the normal characters developed in on organism in response to change in environment or use or disuse of organs during is own life time.

→ Gene Flow: Addition or removal of alleles when individuals enter or leave a population of another locality.
 
→ Mutations: Sudden large and inheritable change in the genetic material, is called mutation.

→ Nebula: Condensed mass of dust and gas.

→ Lithosphere: Crust or surface layer of the earth.

→ Milky way: The huge star family to which our sun belongs to is called milky way.

→ Biopoiesis: View have been put forward from time to time to explain the origin of life, are called biopoiesis.

→ Monera: The group of organisms having prokaryatic,unicellular organisation.

→ Protista: The group of organism having eukaryotic, unicelle organisms.

→ Coprolites: Fossils of faecal matter or droppings.

→ Pangea: The present day continents formed a single big landmass are called Pangea.

→ Biogeography: The study of distribution of animals and plants in space or on the earth surface.

→ Connection Link: Organisms form a bridge between the primitive and advanced group of living organism.

→ Mutants: Individual showing mutation are called mutants.