Biology BIOLOGICAL CLASSIFICATION

### Definitions at a Glance...........

=> color{blue}"Prokaryote" :A prokaryote is a unicellular organism that lacks a membrane-bound nucleus (karyon), mitochondria, or any other membrane-bound organelle. The word prokaryote comes from the Greek (pro) "before" and (karyon) "nut or kernel".

=> color{blue}"Eukaryote" : A eukaryote is any organism whose cells have a nucleus and other organelles enclosed within membranes.

=> color{blue}"Autotrophs" : These organisms synthesise their own food (complex organic substrates) from inorganic substrates, using either light or chemical energy.

=> color{blue}"Photosynthetic Autotrophs" : Prepare their own organic substrates using light energy.

=> color{blue}"Chemosynthetic Autotrophs" : Prepare their own organic substrates using energy from the oxidation of chemical compounds

=> color{blue}"Heterotrophs" : These organisms do not synthesise their own food but depend on other organisms or on dead organic matter for food. They are mostly chemosynthetic.

=> color{blue}"Saprotrophs" : They are the decomposers. They are those organisms that feed on the dead and decaying organic matter and absorb nutrients from them.

=> color{blue}"Parasites" : Parasites arc those organisms that depend on other living organisms for food and shelter.

=> color{blue}"Symbionts" : Symbionts are those organisms of two different species, that are equally benefitted and dependent on each other while living in close association with each other.

=> color{blue}"Binary fission" : Binary fission ("division in half") is a kind of asexual reproduction in bacteria and other simple organisms, that involves the splitting of a parent cell into two equal halves after cell division, producing two new independent cells. The genetic material is replicated during this process and also split equally between the two daughter cells.

=> color{blue}"Bacterial Spore" : A bacterial spore is a structure produced by bacteria that is resistant to many environmental or induced factors (extreme temperatures, lack of moisture/drought, exposure to chemicals and radiation, low nutrient levels, antibiotics and disinfectants) that the bacteria may be subjected to and helps the bacteria to survive in the extreme condtions.

=> color{blue}"Bacterial conjugation" : Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells.

=> color{blue}"Peptidoglycan" : A mesh likepolymer that is composed of polysaccharide and peptide chains and is found especially in bacterial cell walls — also called mucopeptide, murein.

=> color{blue}"Mycorrhizae" : Mycorrhizae are symbiotic association between particular fungi and roots of higher plants.

=> color{blue}"Hyphae" : A hypha is the long, fine and branching filamentous structure that makes up the body (or mycelium) of a multicellular fungus. In most fungi, hyphae are the main mode of vegetative growth. Hey are also present in an oomycete, or actinobacterium.

=> color{blue}"Mycelium" : Mycelium is the vegetative part of a fungus, consisting of network of branching, thread-like hyphae . Generally it lives inside the substrate and is not normally visible.

=> color{blue}"Coenocyte" : A coenocyte is a multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis. Thus, those hyphae which are present as continuous, aseptate tubes filled with multinucleated cytoplasm are called coenocytic hyphae.

=> color{blue}"Zoospores" : Zoospores are the motile spores which are thin-walled and flagellated and produced for asexual
reproduction by some aquatic fungi and algae

=> color{blue}"Aplanospores" : Aplanospores are the thin walled, non-motile spores, used for asexual reproduction in many terrestrial fungal species.

=> color{blue}"Plasmogamy" : Plasmogamy is the process of fusion of the protoplasm of two cells or gametes.

=> color{blue}"Karyogamy" : It follows plasmogamy. Karyogamy is the process of fusion of two nuclei of two fusing cells or gametes.

=> color{blue}"Dikaryon" : This stage follows plasmogamy and precedes karyogamy. It ai the stage where a cell contains two genetically different nuclei, brought together by plasmogamy.

=> color{blue}"Isogamy" : Isogamy is the process in which two physiologically and morphologically similar
gametes fuse with each other.

=> color{blue}"Anisogamy" : Anisogamy is the process in which two physiologically and/or morphologically dissimilar
gametes fuse with each other.

=> color{blue}"Gametophyte" : Gametophyte is the haploid phase in the life cycle of an organism( plant), where sexual reproduction is brought about by the formation of gametes. Such a plant bears the gametes.

=> color{blue}"Sporophyte" : Sporophyte is the diploid phase in the life cycle of organism( plant) , where asexual reproduction leads to the formation of gamete from spores.. Such a plant bears the spores.

=> color{blue}"Alternation of Generations" : It is the phenomenon where the two distinct phases of a life cycle of a plant– the diploid sporophytic and the haploid gametophytic alternate with each other. The gametophyte undergoes sexual reproduction
to form the sporophyte. The sporophyte undergoes sexual reproduction to form the gametophyte.

=> color{blue}"Bacteriophages" : These are the viruses that infect bacteria.