3.1 - classification Flashcards
what is the definition of biodiversity
a measure of the variety of living organisms and their genetic differences
why do we need an international classification system
-so that when scientists around the world are discussing a particular organism they have a way of making sure they are referring to the right organism
-by identifying the number of different organisms in a habitat scientist have a way of quantifying the biodiversity in that area
-it allows scientists to understand how different organisms are related to each other
before Linnaeus’ classification system was created, how were organisms classified into groups
-based on morphology
-organisms were classified into groups based on analogous (physically similar) features that didn’t always have the same-similar genetic origin
what is the order of taxonomic groupings
domain
kingdom
phylum (called division for plants)
class
order
family
genus
species
what are the 3 domains
archaea
bacteria
eukaryota
what kingdom comes after bacteria
eubacteria
what kingdom comes after archaea
archaebacteria
what are archaebacteria
-ancient bacteria thought to be the oldest form of living organism
-live in extreme conditions
what are eubacteria
-true bacteria
-include the bacteria that cause disease
-and useful in the digestive system
describe the kingdom protoctista
uni or multicellular
cellular structure
movement
nutrients acquired
unicellular
cellular structure: nucleus and membrane-bound organelles
movement: some can’t move, some have flagella and cilia
nutrients acquired: some are autotrophs they make their own food by photosynthesis, some are heterotrophs they eat other organisms
describe the kingdom plantae
uni or multicellular
cellular structure
movement
nutrients aquired
multicellular
cellular structure: nucleus, membrane-bound organelles, cell wall made of cellulose
movement: most don’t move, some gametes move by cilia or flagella
nutrients acquired: autotrophic, obtain nutrients through photosynthesis, store energy as starch
describe the kingdom fungi
uni or multicellular
cellular structure
movement
nutrients acquired
uni or multicellular
cellular structure: nucleus, membrane-bound organelles, cell wall made of chitin
movement: no mechanism for locomotion so reproduce through spores
nutrients acquired: heterotrophs, some are saprophytic meaning they feed on decaying materials, and some are parasitic meaning they obtain nutrients by feeding on a living host and harming it in the process
describe the kingdom animalia
uni or multicellular
cellular structure
movement
nutrients acquired
multicellular
cellular structure: nucleus, membrane-bound organelles
movement: cilia, flagella, contractile proteins
nutrients acquired: hetereotrophic, store energy as glycogen
what are the rules for using the binomial system
-the genus goes first and then the species
-the genus must have a capital first letter and the species must be lower-case
-must be written in italics
-after the binomial name is first used, it is abbreviated to the first letter of the genus and then the species name e.g. H. sapiens
what is the morphological species model
what are the limitations
-a model to define a species based only on the physical appearance of the organisms
-the appearance of a species can be effected by many environmental factors
-organisms which show sexual dimorphism have very different physical appearances and wouldn’t be though of as the same species
what is the widely used definition of a species
a group of organisms with similar characteristics that interbreed to produce fertile offspring
what is an advantage of using the reproductive/biological species concept
-organisms of different species may look similar if adapted to survive in the same environment
-it overcomes the issue of sexual dimorphism
what are the limitations of the reproductive/biological species concept
-new species are found that haven’t been observed matting, breeding programmes are expensive and time-consuming
-plants of different but closely related species frequently interbreed to produce fertile hybrid offspring
E.g. lions and tigers can breed, most of the offspring are fertile
-some organisms don’t reproduce sexually
-it is hard to classify fossil organisms because they cannot reproduce
-not all the organisms within a species interbreed, this may be because they are in different geographical places
what is DNA sequencing
a process where the base sequences of all or part of the genome of an organism are worked out
DNA sequencing leads to DNA profiling
what is DNA profiling
a process where the non-coding areas of DNA are analysed to identify patterns
these patterns are unique to individuals but the similarity between patterns can be used to create links between organisms
what is bioinformatics
the development of computer tools and software which organise and analyse raw biological data from DNA profiling and DNA sequencing
it looks for patterns between the data of different organisms, to identify if they are from the same species and determine evolutionary relationships
because it would be impossible for 1 scientist to process all this data
what are DNA barcodes
-it involves looking at short genetic sequence common to all the organisms within the species
-DNA barcodes are unique to each species
-DNA barcodes can be used to identify which species an organism belongs to
how does DNA profiling give information about evolutionary links
-the more mutations there are in the DNA between different organisms, the longer the time since they shared a common ancestor -an average mutation rate is used to estimate how long ago that common ancestor lived
-however there are limitations
-the rate at which DNA mutates can vary
-DNA fragment start to degrade immediately after death, so have to be kept in specific conditions to be preserved
how can fossils be used to determine evolutionary relationships within human evolution
-scientists can extract DNA from suitable fossils
-and analyse them with DNA sequencing and DNA profiling
explain how scientists validate new evidence
-when a piece of research produces useful results and conclusions it is submitted to a scientific journal
-this article will then go through a process of peer review where it is read by several scientists to see if the evidence is reliable
-the article should contain enough information for other scientists to carry out similar investigations to determine if the conclusions can be validated
-scientific conferences may be held where scientists working in the same field get together to talk about new evidence
-providing the opportunity to challenge the validity of results being presented and for the development of new techniques in research
explain how to conduct gel electrophoresis
-place either DNA fragments, RNA fragments, amino acids or proteins in wells inside an agarose plate
-if DNA is used: restriction endonucleases cut the DNA molecule into fragments
-because the order of bases in different organisms DNA is different, DNA from different organisms will be cut into different lengths
-the DNA fragments are dyed which fluoresces when places under UV light and the dye moves faster than DNA fragments (so the current can be turned off before all the DNA fragments reach the positive terminal)
-an electric current passes through the agarose plate
-DNA fragments start at the negative electrode and move towards the positive electrode, because DNA molecules are negatively charged due to the negative phosphate group
-smaller DNA fragments move faster and further along the gel, so smaller fragments are found close to the positive electrode and larger fragments close to the negative electrode
-once electrophoresis is complete the agarose plate is placed under UV light
-DNA fluoresces so the pattern of the bands can be identified
when electrophoresis is used to identify and compare amino acids, is a dye added
no
ninhydrin is added to the agarose plate after electrophoresis
it reacts with the amino acids so they show up as purple patches
what evidence can be used to determine evolutionary relationships
ONGOING
-all organisms in a species contain the same type of blood pigment
-organisms of the same group share the same sequence if amino acids in particular proteins
what is the endosymbiosis theory of mitochondria and chloroplasts
-that mitochondria and chloroplasts once existed as their own prokaryotic organisms
-a eukaryotic cell (can only respire anaerobically) engulfs an aerobic prokaryote (mitochondria) as food
-O2 levels in the atmosphere rise, for some cells it is toxic and others can tolerate it
-by chance in some cells the prokaryotic cells isn’t digested, it respires aerobically providing the cell with more efficient energy to grow
-the eukaryote becomes permanently present in the cell and copies are made and passed to daughter cells
-this new eukaryotic cell engulfs a photosynthetic organism (chloroplast) as food
-by chance it isn’t digested
-it photosynthesises providing the eukaryotic cell with food allowing it to grow more efficiently
-the chloroplast becomes a permanent feature and passed down to offspring
what are the 3 domains
bacteria
archaea
eukaryota
out of bacteria, archaea and eukaryota which 2 are most closely related
eukaryota and archaea
why are some reasons the 2 domain system was removed and the 3 domain system introduced
-archaea replicate through binary fission within a controlled cell cycle
-this is more similar to how eukaryota reproduce also within a cell cycle
-and very different to how bacteria divide
-archaea have unique membrane structures and membrane proteins
-archaea membrane lipids are branched
-bacteria and eukaryota membrane lipids are unbranched
state the names of the kingdoms
-archaebacteria
-eubacteria
-protoctista
-fungi
-plantae
-animalia
describe the process of natural selection by survival of the fittest
-organisms that reproduce sexually show variation in their phenotype
-organisms produce an excess of offspring
-selection pressures, such as a new disease or limited food, mean that organisms with advantageous characteristics survive and reproduce
-they pass the advantageous characteristics down to their offspring
-this process repeats over many generations
what is evolution
the long term changes in the genetic composition of a population of organisms over several generations, as a result of natural selection, bringing about new adaptations or sometimes new species
what is a niche
the role of the organism in the community
what are the 3 types of adaptations
anatomical
physiological
behavioural
what is the definition of anatomical adaptations
adaptations involving the form and structure of an organism
what is the definition of physiological adaptations
adaptations which involve the way the body of the organism works and include differences in biochemical pathways or enzymes
what is the definition of behavioural adaptations
adaptations involving changes to programmed or instinctive behaviour making organisms better adapted for survival
what is the definition if directional selection
natural selection showing a change from 1 dominant phenotype in the population to another phenotype in response to a change in environment
e.g. the change from most moths in the population in industrial cities being light to dark
what is the definition of a selection pressure
changes in the environment/niche of a population, causing natural selection, leading to changes in the phenotype of that population
what are some factors that contribute to the antibiotic resistance problem
-antibiotics are too widely prescribed and used
-wide-spectrum antibiotics are often used to make sure they cure the infection, rather than running tests to determine in the infection is bacterial and which bacteria are involved
-people don’t complete the course of antibiotics
-antibiotics are commoly used in the food chain
what are some measures taken to overcome antibiotic resistance
-reducing use of antibiotics
-reducing use of antibiotics in farm animals
-DNA sequencing will help identify bacteria and find new ways of targetting them, then genetic engineering can be used to produce large amounts of new drugs
-development of new antibiotics
what is speciation
what causes speciation
-speciation is the formation of a new species
-2 groups in a population become separated and experience different conditions
-the 2 groups undergo natural selection so over time the phenotype and genotype of these 2 groups changes
-it reaches a point where if the 2 groups are reunited they cannot interbreed
-so they have become 2 separate species
how does speciation occur from hybridisation
-2 closely related species can interbreed to produce fertile hybrids
-these hybrids sometimes can go on to produce offspring and may be better adapted to their niche
-if the hybrid cannot breed with the same species as the parent organism, the hybrid and parent organism are 2 different species
state the 5 reproductive isolation mechanisms for speciation
geographical isolation
ecological isolation
seasonal isolation
behavioural isolation
mechanical isolation
describe geographical isolation
a physical barrier separates individuals from an original population
describe ecological isolation
2 species inhabit the same region but develop preferences for different part of the habitat
describe seasonal isolation
the time of flowering or sexual reproduction in some parts of the population can shift away from the normal time of the population, eventually leading to the 2 groups reproducing months apart
describe behavioural isolation
some individuals in the population change their mating display or pattern, causing the rest of the population to not recognise them as potential mates, so won’t reproduce with them
describe mechanical isolation
a mutation occurs that changes the genitalia in animals or the relationship between the stigma and stamens in flowers of some individuals in the population, so it is physically impossible for them to reproduce with the rest of the population
what is allopatric speciation
takes place when populations are physically or geographically separated and there can be no interbreeding or gene flow between these populations
what is meant by endemic
an endemic species is a species that evolves from geographical isolation and can only be found in one place
so an endemic species forms as a result of allopatric speciation
what is adaptive radiation
when one species evolves rapidly to form many other different species, which all fill diferent ecological niches
usually occurs after allopatric speciation
what is sympatric speciation
takes place between populations of a species living in the same area that become reproductively isolated due to mechanical, behavioural, or seasonal changes
gene flow continues to some extent between the populations as speciation occurs
