ORIGIN AND EVOLUTION OF LIFE

ORIGIN AND EVOLUTION OF LIFE

Protobiogenesis: The origin of life on earth is called protobiogenesis.

Cosmozoa/ Panspermia: The hypothetical seeds or spores which came from a distant planet and led to the beginning of life are called cosmozoa.

Abiogenesis: The evolution of life or living organisms from inorganic or substances are called abiogenesis.

Biogenesis: The evolution of life or living organisms from living matters is called biogenesis.

Protobionts: The first form of life formed by the combination of Nucleic acids along with inorganic and organic molecules are called protobionts.

Coacervates: A colloid-rich viscous liquid phase is called coacervates.

Ribozymes: RNA having Catalytic activity is called as Ribozymes.

Somatoplasm: The protoplasm of the somatic cells is called as somatoplasm.

Germplasm: The protoplasm of the germ cells (Sperm and Egg cells) is called as germplasm.

Natural Selection: According to Darwin, the principle by which useful variations are preserved by nature, is called ‘Natural Selection.

Speciation: Formation of new and distinct species during the evolution is called speciation.

Saltation: A single step large mutation is called saltation.

Mendelian population: Small interbreeding group of a population is referred to as ‘Mendelian population’.

Gene pool: The sum total of genes in a Mendelian population is called gene pool.

Gene frequency: The total number of alleles at a given locus is called gene frequency.

Genetic variations: The change in gene and gene frequencies is known as genetic variation.

Gene Mutation: Sudden permanent heritable change is called mutation.

Point mutation or Gene mutation: Mutation that occurs within a single gene is called point mutation or gene mutation.

Crossing over: Exchange of genetic material occurs between non-sisters chromatids of homologous chromosomes are called crossing over.

Gene flow: Gene flow is the movement of genes into or out of a population is called gene flow.

Genetic drift: Any random fluctuation (alteration) in allele frequency, occurring in the natural population by pure chance, is called genetic drift.

Chromosomal aberrations: The structural, morphological change in chromosome due to rearrangement is called chromosomal aberrations.

Deletion: Loss of genes from chromosome is called a deletion.

Duplication: Genes are repeated or doubled in number on a chromosome are called duplication.

Inversion: A particular segment of a chromosome is broken and gets reattached to the same chromosome in an inverted position due to 180-degree twist is called inversion.

Translocation: Transfer (transposition) of a part of a chromosome or a set of genes to a non-homologous chromosome is called translocation.

Isolation: The separation of the population of a particular species into smaller units which prevents interbreeding between them is called isolation.

Geographical Isolation: When an original population is divided into two or more groups by geographical barriers such as river, ocean, mountain, glacier etc. These barriers prevent interbreeding between isolated groups. It is also called as physical isolation.

Reproductive Isolation: Isolations occur due to change in genetic material, gene pool and structure of genital organs to prevent interbreeding between the populations is called reproductive isolation.

Habitat isolation or (Ecological isolation): Members of a population living in the same geographic region but occupy separate habitats so that potential mates do not meet is called habitat isolation.

Seasonal or temporal isolation: Members of a population living in the same geographic region but are sexually mature at different years or different times of the year is called seasonal or temporal isolation.

Ethological isolation: The specific mating behaviour which prevents the members of the population to mate is called ethological isolation.

Mechanical Isolation: Members of two populations have a difference in the structure of reproductive organs is called mechanical isolation.

Hybrid sterility: Hybrids develop to maturity but become sterile due to failure of proper gametogenesis is called hybrid sterility.

Gene flow: It is the transfer of gene during interbreeding of populations that are genetically different.

Genetic drift: Any alternation in allele frequency in the natural population by chance is called genetic drift.

Adaptive Radiation: The process of evolution which results in transformation of original species to many different varieties is called, adaptive radiation.

Palaeontology: The study of ancient life with the help of fossils is called palaeontology.\

Fossilization: The process of fossil formation is called fossilization.

Actual remains: The plants, animals and human bodies got embedded in the permafrost of arctic or alpine snow remain preserved in the actual state is called actual remains.

Moulds: These are the hardened encasements formed in the outer parts of organic remains which later decayed leaving cavities.

Cast: The hardened pieces of mineral matter deposited in the cavities of moulds are called a cast.

Compressions: The internal structure is absent but a thin carbon film indicates the outline of external features are called compressions.

Connecting link (missing link): Link between the two classes of species is called connecting link.

Homologous organs: Organs which are structurally similar but perform different functions are called homologous organs.

Analogous organs: Organs which are structurally dissimilar but functionally similar are called analogous organs.

Convergent evolution: Different organisms show structural similarities due to similar functions or habitat are due to convergent evolution.

Divergent evolution: when two groups of the same species evolve differently due to different environmental conditions are called divergent evolution.

Vestigial organs: The organs which do not have any functions in the body are called vestigial organs.

Allopatric speciation: Formation   of a new species due to separation of a segment of the population from the original population by a geographical barrier is called allopatric speciation.

Sympatric speciation: Formation of species within single population without geographical isolation.

Hybridization: The process of producing offspring by mating two parents from different varieties or species is called hybridization.