AIIMS: Revision Terminology Part 8

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  • Recapitulation theory :- Biogenetic law by Haeckel – Ontogeny repeats phylogeny

  • Age of fossil – C14 – dating & amount of pb in rocks.

  • Charles Darwin (Birth 1804) survey in HMS beagle vie west Chile, Galapagos island, New Zealand, Tasmania, South Africa and returned in 1836 to S. America(falmouth) & Stayed in gala pages island for 5 year

  • Neo-Darwinism :-

(1) Genetic variability

(2) Natural selection – differential reproduction

(3) Reproductive isolation

  • J Lederberg – Replica plate technology – demonstration process of selection of antibiotic resistant strains of bacteria

  • Heterozygous Sickle cell individuals can fight malaria better than normal man Glucose 6 phosphate dehydrogenase deficiency is common in Negroids. –Hb is denatured & deposited on cell member, if they beans Hb destroyed. = FAVISM due to premature death of RBS such person malarial life cycle is not completed & Protected from malaria.

  • Speciation = formation of new species – gradual

  • Speciation = formation of new species – rapid – by polyploidy

  • Gene freq.

X AA N(total of individual) = X + Y + Z

Y Aa Number of alleles = 2XN

  • Ratio of A alleles in population (p) = = Or

  • Ratio of a alleles in population (r) = =

  • 1st chemical mutagen = mustard gas (sulpher mustard)

  • HNO2 & alkylating agent like mustard gas are mutagens to both replicating & non replicas DNA

  • Mutagens only to replicating

(1) acridine dye – like proflavin bound to DNA

(2) Bass analogs – 5 – Bromouracil, 2- aminopurine

  • Genetic drift – in small population – Cause change in allele frequency when few Indi duals colonize a new habitat or when population greatly reduced due to a natural crash

  • Gene flow – transfer of alleles between the population

  • Cladogenesis (Divergent evolution) –

  • Convergent evolution – 2 different ancestors give rise to organism with similar physical & functional Character just as they are adapted to same environment

  • E.g., Euphorbia & cacti belong to difference families but adopted to same climate.

  • Coevolution – in nature species frequently interact so closely that evolutionary changes in one causes evolutionary adjustment in others – Flowering plant – insect pollinator predator – prey relation

  • Founder effect - species Type of genetic drift influencing genetic makeup of some population separating from the man population – fare less genetic variation & has a distinctive make up.

  • E.g., Dunbar’s of eastern - Pennsylvania migrated from Germany & U. S. in 1st century due to religious reasons they did not marry outside their caste/sect so the frequency of genes in 2 are different.

  • Bottleneck effect – due to drastic red in number of individuals in a population due to environmental factor e.g. population of cheetah of S & E. Africa reduced, now if provide protection only a part of the original gene pool will be recovered

  • Industrial melanism – directional selection on active – changing environment will lead to change in genotype/phenotype of population