Classification Of Organisms Flashcards
Why have scientists designed classification systems
As a way to organize biodiversity.
Living organisms are divided into groups and subgroups according to similarities and shared characteristics
Taxa
The groups into which organisms are classified
The formal scientific classification of organisms is known as
Taxonomy
What made classification systems complex for scientists
The structure of cells, microorganisms, evolution, genetics and molecular biology
Two kingdom system
In 1758,a Swedish botanist, Carl Linnaeus classified living organisms into two kingdoms:Plantae(plants) and Animalia(animals)
Linnaeus developed a hierarchical system of classification where 7 categories (taxa) under each kingdom where used.
Kingdom>phylum/division >class>family> genus >species
The above categories are based on shared physical properties within each group. Each level becomes even more specific. Organisms within the same family have more in common than organisms within the same order.
A kingdom is subdivided into phyla for…. But in….. The term division is used
Animal, plants
Biological classification
System used to sort out living things based on their similarities
Carl Linnaeus used this system to separate
Plants that can make their own food, can’t move and are auto trophic and animals that can make their own food, can move and are hetero trophic
Kingdom plantae characteristics
Can’t move
During daytime they are involved in photosynthesis as they need sunlight and obtain carbon dioxide and liberate oxygen
Unlimited growth for certain plants
Excretory and nervous system aren’t present
They reserve food material(starch)
Reproduce asexually(not direct contact) and Fertilization takes place with the help of agents like wind, water etc..
Plant cells don’t have Centrosomes so they may have inorganic crystals
Kingdom Animalia characteristics
Definite body shape and no branches
Move place to place but can’t make their own food.
Release carbon dioxide and take in oxygen from plants
Can’t partake in photosynthesis
Grow a certain length, size and width
Excretory and nervous system are advanced
Reserve food materual(glycogene)
Centrosomes are present and have organic crystals
Disadvantages of the two kingdom system
Unicellular organisms do not fit in either of the kingdoms. This system does not provide a separate distinction for such organisms.
It grouped the photosynthetic organisms (plants) and the non-photosynthetic organisms (fungi) in the same kingdom, Plantae.
No distinction between the eukaryotes and prokaryotes.
Five kingdom system
The two kingdom was expanded into a five kingdom system as more scientific information about organisms was obtained. In 1969,Robert Whitaker proposed the five kingdom system
5 kingdoms
Monera(bacteria)
Protista
Fungi
Animalia
Plantae
What criteria was used to classify organisms into the five kingdoms
Body structure - unicellular/multicellular/colonies
Cell structure - presence/absence of a nucleus:organelles(chloroplasts)
Composition of cell wall– cellulose/chitin/no cell wall
Motility - mobile /immobile
Mode of nutrition - autotroph/heterotroph
Method of reproduction - binary fission/asexual/sexual
Prokaryotes
Organisms that don’t have a true nuclei
Their DNA is not enclosed by a nuclear membrane and therefore occurs free in the cytoplasm
No true organelles in the cytoplasm
Monera are prokaryotes
Eukaryotes
Organisms with cells that have true nuclei.
Their DNA is enclosed by a nuclear membrane and therefore occurs inside the nucleus
True organelles occur in the cytoplasm. All Protista, fungi, Plantae and Animalia are all eukaryotes
Characteristics of kingdom monera
Unicellular have no true nuclei and therefore prokaryote
Bacterium cell is surrounded by cell wall
Some bacteria are autotroph ice and produce their own organic substances by photosynthesis
Majority of the bacteria are heterotrophic and cannot produce their own organic substances. Heterotrophic bacteria are either parasites or saprophytes, or they live Mutualistically with other organisms.
Reproduction occurs asexually by binary fission whee a single cell divides into two cells of identical DNA composition
Parasitic
Dependent on living organic matter for food where organisms live together (symbiosis) and one benefits and the other is harmed.
Saprophytic
Dependent on dead organic matter for food
Mutualistic
Living together with other organisms so that both can benefit from the relationship (a type of symbiosis)
Characteristics of kingdom Protista
Distinguished into 3 groups :
Protozoa-animal like, unicellular and heterotrophic organisms
Algae - plant like. Autotrophic (have chlorophyll and can photosynthesise)
Slime moulds and water moulds fungus like organisms
Subgroups :
Chrysophytes:Chrysophytes are agroup of algae with yellowish green to golden brown pigments.They are usually found in freshwater and marine habitats with low calcium(desmids)
Dinoflagellates-Dinoflagellates aresingle-celled aquatic organisms with two flagella found in fresh and saltwater. Usually photosynthesise and the color they appear is dependent on the key pigments in their cell: red,, brown, green.
Euglenoids:Euglenoids aresingle-celled protists
Instead of the cell wall, a protein-rich cell membrane known as pellicle is present.
They bear two flagella on the anterior end of the body.
A small light-sensitive eye spot is present.
Magnification of cells
The formula to calculate magnification is: magnification = size of image / real size of object12. This equation can be rearranged to calculate the actual length of the cell and the magnification used as well as the length of the image3. To calculate magnification using the formula in micrometres, convert the measurement of the cell from mm into micrometres4
Types of monera
Coccus(circles)
Vibro(pea shaped)
Bacillus (oval)
Spirillum(, spirals)
Protista moves by means of
Flagella, cilia and cyclosis
Reproduction for Protista
Asexual by binary fission and they live in moist environment as they are aquatic
Characteristics of fungi kingdom
Distinguished into 3 groups:
Yeast, mushrooms and moulds.
Yeasts are unicellular while mushrooms and moulds are multicellular.
All fungi have true nuclei and are therefore eukaryotic.
Cell walls containing cellulose and chitin
Fungal body consists of a mass of branched filaments or hyphae
Fungi have no chlorophyll and are therefore heterotrophic.
Most fungi are saprophytes and live off dead organic plant and animal Matter like bread mould and mushroom.
Some are parasites and feed on living matter causing athletes foot
And some are Mutualistic
Reproduction occurs :
Unicellular fungi :asexually by binary fission
Multicellular fungi : asexually by means of spores during favorable conditions
Sexually by means of gametes during unfavorable conditions
Plant kingdom is divided into 4 divisions
Bryophytes-mosses
Pteridophytes-fern
Gymnosperms-conifers
Angiosperms-flowering plants
Kingdom Animalia is divided into 9 phylum
Porifera-sponges
Cnidaria-jellyfish
Platyhelminthes-flatworms
Nematoda-round worms
Annnelida-earth worms
Mollusca-snails
Echinodermata-starfish
The used it common names for living organisms may cause confusion because the same organisms in different regions have different names or same name given to different species or scientists speaking different languages for this reason
A binomial (double-name) system was designed by Carl Linnaeus for the naming of living organisms, based in Latin as scientists throughout the world used it.
How to make a scientific name
The genus name is written with a capital letter and the species with a small letter then underlined afterwards.
Dichotomy
Divided into two parts. It was a key used to consist with a series of options that lead to the user to the correct name of an organism
mutualistic
living together with other organisms so that both benefit from the relationship. a type of symbiosis
monera- reproduction happens asexually
binary fission where a singl cell divides into 2 identical cells of the same dna composition.
species
group of related organisms that interbreed and produce fertile offspring.
cambrian explosion
early forms of most animal groups
mass extinction
when many species dissapear over the same period of time
due to physical causes like
climate change; volcanic eruptions and continental drift
moulds
hard part of an organism trapped in sediment
