Classification and evolution Flashcards
Why do we classify living things
- convenience
- makes study of living things more manageable
- makes it easier to identify organisms
- helps see the relationships between species
What is the modern classification hierarchy
taxonomic groups
Domain Kingdom Phylum Class Order Family Genus Species
Daddy King Philip Came Over For Good Spaghetti
Who devised the first system of classification and how did they do it
Carl Linnaeus
- grouped organisms based on similarity in their features
- divided into taxonomic groups, originally Kingdom, Class. Order, Genus, species but has been modified and expanded
What is a domain
the highest taxonomic rank
three domains: archaea bacteria. eubacteria, eukaryote
What is a kingdom
five kingdoms:
plantae, Animalia, fungi, protoctista - eukaryotes
prokaryote
What is a phylum
group of organisms that all have the same body plan i.e. possession of backbone
chortada - nervous system protected by vertebal column
Arthropoda - hard exoskeleton and jointed limbs i.e insects and spiders
What is a class
a group of organisms that possess all the same general traits
i.e. the same number of legs
What is an order
sub-division of class using additional info about the organisms i.e. mammal is divided into Carnivora and herbivore
What is a family
a group of closely related genera
i.e. within Carnivora there is dogs and cats
What is a genus
A group of closely related species
What is a species
the basic unit of classification
- show some variation but are essentially the same
What happens as you decrease in taxonomic groups
Becomes increasingly difficult to separate closely related species and to place accurately
What is the binomial system
a system that uses the genus name and the species name to avoid confusion when classifying organisms
i.e. Homo sapiens
Homo - genus (always given uppercase first letter)
sapiens - species (written in italics/ underlined)
Why does grouping organisms with a common name not work
- same organisms may have different common names in different parts of one country
- different names are used in different countries
- translations of languages may give dialects different names
- same common name may be used for same species in different parts of the world
What is the universal language Linnaeus used
Latin
What is the biological definition of a species and what’s wrong with it
’ a group of organisms that can freely interbreed to produce fertile off spring’
-does not work for organisms that can reproduce asexually/ fossils
What is the phylogenetic definition of a species
’ a group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry, genetics ‘
What do similar species all occupy
the same niche in an ecosystem
- this allowed for easier classification
- mistakes could still be made only could get even more accurate classification with microscopes
What organisms did not fit into their kingdoms with the 2 kingdom classification
fungi - roots but do not photosynthesise
euglena - can move and photosynthesise
What are the characteristics of an organism in the prokaryote kingdom
- have no nucleus
- loop of DNA that is not arranged in linear chromosomes
- naked DNA
- no membrane bound organelles
- smaller ribosomes then in other groups
- cells smaller than eukaryotes
- may be free living or parasitic
What are the characteristics of an organism in the protoctista kingdom
- eukaryotic
- single celled (many algae are multicellular though)
- variety of forms ( only common feature is don’t belong to any of the other four kingdoms)
- show various plant/ animal features
- mostly free-living
- autotrophic/ heterotrophic nutrition - some photosynthesize, some ingest prey, some feed using extracellular enzymes, some are parasites
What are the characteristics of an organism in the plantae kingdom
- eukaryotic
- multicellular
- cells surrounded by a cellulose cell wall
- autotrophic (absorb simple molecules and build them into larger organic molecules)
- contain chlorophyll
What are the characteristics of an organism in the Animalia kingdom
- eukaryotic
- multicellular
- heterotrophic ( digest large organisms to form smaller molecules for absorption)
- usually able to move around
What is convergent evolution
two organisms can adapt in the same way and look very similar
- could be grouped in the same taxonomic group based on observable characteristics
How are biological molecules used in classification
- two organisms with similar are closely related as they have not evolved separately for long
- differences reflect the evolutionary relationships - backed up scientific research and clarify
What is cytochrome C
used in respiration - in all living organisms that respire
How can cytochrome C be used to classify organisms
- not identical in all living species
- different sequences of amino acid allows scientists to draw conclusions:
If sequences are the same must be closely related
If different not so closely related
More differences the less closely related the species
How does cytochrome C differ in humans and different organisms
humans and chimpanzees identical - close
Humans and rhesus monkey, one difference - close
Humans and dogfish, 11 differences - not close
What is DNA
- provides the genetic code, the instruction for producing proteins
- universal - particular sequence of DNA codes for dame sequence of amino acids in all living organism
How can DNA be used in classification
- DNA can contain mutations
- compare DNA sequences- more similar the more closely related the two species
What is the three Domain classification
Carl Woese
- based ideas on RNA gene
- divided prokaryote into eubacteria and archaea bacteria
Why did Woese divide the prokaryotes
fundamental differences in structure:
- different cell membrane structure
- different enzymes (RNA polymerase) for synthesising RNA
- flagella with different internal structure
- no proteins bound to genetic material
- different mechanisms for DNA replication and synthesising RNA
How is archaea bacteria similar to eukaryotes
another fundamental difference to eubacteria
- similar enzymes ( RNA polymerase) for synthesising RNA
- similar mechanisms for DNA replication and synthesising RNA
- production of some proteins that bond to their DNA
What did Woese argue
RNA and DNA are basic mechanisms that translates genes into visible characteristics
- differences between bacteria therefore fundamental
What is artificial classification
Done for convenience so easy to remember:
- based on a few characteristics
- doesn’t reflect evolutionary relationships
- provides limited information
- stable
What is natural classification
taxonomic groups:
- uses many characteristics
- reflects evolutionary relationships
- provides lots of useful information
- may change with advancing knowledge
Why is natural classification between different organisms in the modern world useful
If you want to find out more about endangered species, research can be carried out on a similar species that is not endangered
- helps make conservation more successful
What is phylogeny
the study of evolutionary relationships between organisms
How does a phylogenetic tree work
- any two living species today had had a common ancestor alive in the past
- the time at which the two species start to evolve separately is a branch in the tree
- the more recent the common ancestor, the more closely related the two species
What did Darwin come up with
Natural Selection - features of the environment apply a selective pressure on the reproduction of individuals in an environment
What were Darwin’s observations
- Offspring generally appear similar to their parents
- No two individuals are identical
- Organisms have the ability to produce large numbers of offspring
- populations in nature tend to stay the same size
What were Darwin’s conclusions
- there is a struggle to survive
- better adapted individuals survive and pass on their characteristics
- over time a number of species gives rise to a new species
How were fossils used as evidence for evolution
They showed that modern species had similarities to the fossils, but had variations to adapt to their environment
How are biological molecules used as evidence for evolution
- biological molecules are in all living species, if one species gives rise to another suggests the same - all have one common ancestor
- more closely related, more similarities in biological molecules
- cytochrome c e.g.
How is mitochondria used in evolution
- mDNA is passed on through the mother during sexual reproduction
- mutates more as doesn’t have the same proof reading systems as DNA
- lots of variations in mDNA in people in different parts of the world
- can be used to find origins of different races
What is standard deviation
A measure that spreads out the mean
- low means data has a low range and are grouped closely to the mean = reliable
- high means data has a large range and are less well grouped = unreliable
How do you work out the spread of the data sheet
mean +/- the standard deviation
if leaves show a normal distribution
68 % lies within range of mean +/- SD x1
98% lies within range of mean +/- SD x2
- anything outside is viewed as anomalous
What is the T-test
Used to compare two means, whether the difference between the two means is a significant difference
What must you do before starting the T-test
State a null hypothesis - there is no significant difference between the two sets of means of data
- t test will test whether we can reject/accept this hypothesis
What is the number of degrees of freedom
(sample size - number of data sets)
i.e. ( n1- n2 ) -2 = 18
must be considered when calculating the t-tests significance
How do we know if we should accept/ reject the null hypothesis
Read off table the value of 18 has 2.1 freedom i.e.
If greater then 5% value then accept if below then reject
What is a correlation co-efficient
used to consider the relationship between two sets of data
Spearman’s rank correlation tells us whether the two sets of data are correlated or not
How to do the spearman’s rank correlation
D- difference between the values
state null hypothesis
if under critical value then no correlation
What is adaption
a characteristic that enhances survival in a habitat
What will a well adapted organism be able to do
- find enough food to photosynthesise well
- find enough water
- gather enough nutrients
- defend itself against predators and disease
- survive physical conditions of environment
- respond to changes in environment
- have sufficient energy to allow reproduction
What are the different ways an organism can adapt
anatomical/ behavioural/ physiological
Why is Marram Grass adapted
It is adapted to living on sand dunes where there is little water available so adapted to take up as much water as possible
What does anatomical mean
structural features that enhances organisms survival
What are the anatomical adaptions of marram grass
1) long roots- enable plant to reach water deep underground
2) Roots spread over wide area - absorb water where its available, helps stabilise sand dune
3) Leaves are curled - reduces SA exposed to the wind, traps air inside against lower epidermis so moisture can build up in enclosed space
4) Lower epidermis is covered in hairs - reduces air movement so water retained close to lower epidermis
5) Lower epidermis is folded to create pits in which stomata are positioned - water vapour build up in pits reducing loss
6) Low density of stomata - fewer stomata means less water lost
7) Leaf covered in thick waxy cuticle - reduced evaporation of water from the leaf
What are behavioural adaptions
behaviour aspect of organism that enhances survival in habitat i.e. earthworm is blind so contracts and hides in burrow, rapid withdrawal
- marram grass curls up leaves/ covered by sand grow more quickly to reach sunlight
What is a physiological/ biochemical adaption
Adaption that ensures correct functioning of cell processes
What are the physiological adaptions of marram grass
1) ability to roll up leaves due to specialised hinge cells in lower epidermis
- Cells lose water and turgidity when water is scarce curl up leaf
- water is available hinge cells become turgid opening leaf for easier access to CO2 and photosynthesis
2) guard cells work in a similar way to open and close the stomata
- non turgid cells close the stomata
- turgid cells open the stomata
3) Marram is not very salt tolerant but maintains Cell water potential lower then other plants
- able to survive salty conditions of the sea
4) Leaves contain many lignified cells that provide support when turgidity is lost
- keeps leaf upright when water is not available
What organisms show an example of convergent evolution
Moles / marsupial moles have:
- cylindrical body
- small eyes
- strong front legs
- large claws on front legs
- short fur
- short tail
What is variation
the presence of differences between individuals
What is intraspecific variation
the variation of individuals in the same species
What is interspecific variation
the differences between species
What is continuous variation
variation where there are two extremes and a range of values in between
- most individuals are close to the mean value at the extremes number of individuals showing that is quite low
- usually regulated by more than one gene and can be influenced by the environment in which the organism lives
e. g. height, length of a leaf, length of stalk
What is discontinuous variation
where there are distinct categories and nothing in between
- may be evenly distributed or more then one type in one category than the others
- regulated by a single gene and not influenced by environmental factors
e. g. gender/ human blood groups
What are the two causes of variation
genetic and environmental
What is inherited/genetic variation
- genes we inherit from parents have different combinations of alleles in each living organism
What is environmental variation
environment affects characteristics
i.e. Hawthorne tree constantly cut will become more bushy and stop growing as much
What are combined effects
Genetic and environmental variation being connected to perform variation
- humans have become taller as a result of a better diet
- not all our genes are active at the same time i.e. adolescence certain genes are being switched on/off
- changes in environment can affect genes that are active
How does natural selection work
1) In any population variation occurs as a result of mutations
2) if there are different varieties there will be competition for food/ space
3) selection pressure is exerted on the environment
4) Organisms most adapted to environment will survive as they have the most advantageous alleles
5) They reproduce and pass on genetic mutations to offspring
6) Over time this could give rise to a new species
What wont be passed onto offspring
Variation due to environmental factors such as a scar
Is evolution still happening today
Yes - whenever a species or group of organisms are placed under a new selection pressure (use of antibiotics/pesticides) different characteristics will be selected evolution will occur = most obvious in organisms with a short life cycle
How do bacteria develop resistance to antibiotics
1) mutation causes bacterium to develop that has resistance to a particular antibiotic - this causes variation in a population
2) mutation will give an advantageous allele to bacterium that allows it to develop resistance to the antibiotics and survive under a selection pressure
3) Resistant bacterium will survive, whilst those without advantageous allele will not, and pass on advantageous allele to next generation
4) This creates a new strain of bacterium resistant to antibiotics
Why ahs antibiotic resistance occurred
Because of the overuse of antibiotics in humans/ agriculture and people not taking the full course of antibiotics
What is the problem of antibiotics developing resistance to insecticides
Insecticide is designed to kill pests and exerts a strong selection pressure
- if individual has genetic mutation may survive and become more resistant as has advantageous allele
- Can cause problems in the food chain as when insect is eaten causes predator to receive more concentrated does of insecticide
- occurred with DDT insecticide causing thinning of eggs in bald eagle population
What happens if you don’t take the full course of antibiotics
Resistant bacteria with advantageous alleles will survive selection pressure and reproduce in the blood creating a new strain resistant to the antibiotics
- some doctors now prescribe multiple antibiotics to reduce the chances of survival
