Students can go through AP Inter 2nd Year Zoology Notes 7th Lesson Organic Evolution will help students in revising the entire concepts quickly.
AP Inter 2nd Year Zoology Notes 7th Lesson Organic Evolution
→ Evolution is the branch of biology that deals with the origin of life and the diversity of organisms on the earth through ages.
→ Theory of special creation states that organisms on were created by a divine power.
→ Theory of spontaneous generation theory says that life originated from non-living (or) decaying and rotting substances like manure, dew etc.,
→ Theory of biogenesis theory states that living organisms originate from pre-existing
organisms.
→ Theory of origin of life states that primitive organisms evolved from the inorganic substances as a result of physical forces such as lighting, ultraviolet radiation, volcanic activities etc.,
→ Study of prehistoric life through fossils called palaeontology.
→ Lamarckism – proposed by Jean Baptiste de Lamarck. It deals with the influence of environment-on organisms, use (or) disuse of organs and the inheritence of acquired characters.
→ Darwinism – proposed by Charles Robert Darwin.
→ Darwin’s theory of natured solution explain how evolution might have occurred in nature.
→ Mutation thoery was proposed by Hugo de vires.
→ Mutations are sudden, random inheritable changes that occur in organisms.
→ Hardy – Weinberg equilibrium – States that the allelic frequencies in a population will remain constant from generation to generation under certain conditions.
→ The process by which variations appear and new species are formed is called the Mechanism of evolution.
→ The forces that bring changes in the gene pool of populations are called evolutionary forces.
→ The movement of alleles from one population to another is called gene flow.
→ The existence of deleterious genes within the populations is called genetic load.
→ The change in the frequency of agene that occurs merely by chance and not by selection, in small populations, is called genetic drift.
→ Speciation is a process by which one species, evolves into one (or) more different species.
→ Organic means ‘living organisms’; evolution means ‘unfold’.
→ Organic evolution is the development of various types of more complex organisms.
→ Postulates of Darwin’s theory of natural selection: (i) Over production (ii) Struggle for existence (iii) Variation and heredity (iv) survival of the fittest or natural selection.
→ Biogenetic law: ‘Ontogeny repeats Phylogeny’. [IPE]
→ Atavism: Sudden reappearance of some vestigial organs in a better developed condition. [IPE]
→ Genetic load: Existence of deleterious genes with in a population is called genetic load. [IPE]
→ Homologous organs: The organs which have similar structure and origin but not necessarily the same function are called homologous organs. Ex: Flipper of Whale, wings of bat. [IPE]
→ Analogous organs: The organs which have different origin but have same function are analogous organs. Ex: Wings of butterfly and wings of birds. [IPE]
→ Mutations: These are sudden, random inheritable changes that occur in organisms. [IPE]
→ According to Darwin, the organic evolution is due to intraspecific competition. [NEET-13]
→ Genetic drift is the variation in gene frequencies within populations can occur by chance rather than by natural selection. [NEET-2013]
→ Forelimbs of cat, lizard used in walking, forelimbs of whale used in swimming and forelimbs of bats used in flying are an example of homologous organs. [NEET-2014]
→ A population will not exist in hardy-Weinberg equilibrium if individuals mate selectively. [NEET-2015]
→ Homo habilis had the smallest brain capacity. [NEET-2015]
→ The wings of a bird and the wings of an insect are analogous structures and represent covergent evolution. [NEET-2015]
→ Industrial melanism is an example of natural selection. [NEET-2015]
→ Flipper of whale structure is homologus to the wing of a bat. [NEET-2016]
→ Analogous structures are a result of convergent evolution. [NEET-2016]
→ Genetic drift operates in small isolated population.[NEET-2016]
→ Brain Sizes: [NEET-2019]
Homo habilis : 650-800cc; Homo neanderthalensis – 1400cc;
Homo erectus- 900cc; Homo sapiens- 1350cc
→ The most important cause for animals and plants being driven to extinction is Habitat Loss & Fragmentation. [NEET-2019]
→ Flippers of penguins and dolphins are examples of convergent evolution. [NEET-2020]