4.3 Classification and evolution Flashcards
why do we classify organisms
- more convenient
- to make the study of living things more manageable
- to make it easier to identify organisms
- to help see the relationships between species
what are organisms classified into
domain kingdom phylum class order family genus species
what are the 3 domains
archaea
eubacteria
eukaryote
what are the 6 kingdoms
archaebacteria eubacteria plants animals fungi protoctists
how are organisms sorted into the phylum category
organisms which have the same body plan (possession of backbone)
how are organisms sorted into the class category
possess same general traits (no. of legs)
how are organisms sorted into the order category
subdivision of class (omnivore, herbivore, carnivore)
how are organisms sorted into the family category
group of closely related genera
how are organisms sorted into the genus category
group of closely related species
how are organisms sorted into the species category
basic unit of classification- sorted by variation
describe the binomial naming system
- used to name organisms
- genus (capital letter) and species (lowercase) name are used
- must be underlined
- in latin so its universal
why does using a common name for organisms not work well
- different countries call organisms differently
- some organisms may have different common names in diff parts of a country
- translation of languages may give different names
- same common name may be used for different species in different parts of the world
define the biological definition of species
a group of organisms that can freely interbreed to produce fertile offspring
define the phlylogenetic definition of a species
a group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry and genetics
describe the features of archaea and eubacteria
- no nucleus
- have loop of DNA
- naked DNA
- no membrane bound organelles
- smaller ribosomes
- smaller cells than eukaryotes
- may be free living or parasitic
describe the features of protoctists
- eukaryotic
- mostly single-celled
- show wide variety of forms
- show various animal/plant-like features
- mostly free living
- have autotrophic or heterotrophic nutrition
define autotrophic and heterotrophic
auto- can photosynthesise
hetero- can break down large molecules
describe the features of fungi
- eukaryotic
- exist as single cells or have mycelium that consist of hyphae
- walls made of chitin
- cytoplasm is multinucleate
- mostly free living and saprophytic(cause decay or organic matter)
describe the features of plants
- eukaryotic
- multicellular
- cells surrounded by cellulose cell wall
- autotrophic
- contain chlorophyll
describe the features of animals
- eukaryotic
- mulyicellular
- heterotrophic
- usually able to move around
what did Linnaeus use to classify organisms
observable features
what can we now use to classify organisms
biological molecules (cytochrome C) DNA
how can we use cytochrome C to classify organisms
-its a protein found in respiration
-not identical in all species
If we compare the sequence of amino acids in cytochrome C of 2 species:
=sequences the same, must be closely related
=sequences different, not closely related
=the more differences in sequence, the less closely related
how can we use DNA to classify organisms
found in all organisms and provides genetic code-instructions for producing proteins
comparison of DNA sequences can determine how closely 2 species are related
how are eubacteria different to archaea and eukaryote
- eubacteria have different cell membrane structure
- different enzymes for synthesising RNA
- different mechanisms for DNA replication and synthesising RNA
what features do archaea share with eukaryotes
- similar enzymes for synthesising RNA
- similar mechanisms for DNA replication and synthesising RNA
- production of some proteins that bind to their DNA
define phylogeny
the study of the evolutionary relationship between organisms
describe artificial classification
classification done for convenience (easy to remember or to find)
- based on only a few characteristics
- does not reflect evolutionary relationships
- provides limited info
- is stable
describe natural classification
organised into hierarchy
- uses many characterises
- reflects evolutionary relationships
- provides lots of useful info
- may change with advancing knowledge
define common ancestor
when a species is an ancestor of two or more species later in time
they do not survive today (extinct)
define monophyletic
group of organisms that descended from a common ancestor
define classification
process of sorting things into groups
define natural selection
the term used to explain how features of the environment apply a selective force on the reproduction of individuals in a population
proposed by Charles darwin- Galapagos island- finches had different beaks to consume different foods
what evidence do we have for natural selection
fossil evidence
biological molecules
how does fossil evidence show natural selection
- old species have died out and new one have arisen
- new species that appeared are often similar to old ones in the same place
- many similarities between living and fossil species
- modern species had variations-better adapted to environment
- fossil species were larger than modern species
how do biological molecules show natural selection
- certain molecules suggest that all species arose from one original ancestor
- closely related species separated recently
- species that are less related have more differences in biological molecules
- cytochrome c
- structure of DNA
describe the process of natural selection
- variation occurs because of mutation
- there is a selection pressure
- organisms that are best adapted to the environment survive, they have advantageous alleles, others die
- they reproduce and pass on alleles to offspring
- over time, can lead to new species
define selection pressure
competition for food, space, water, sunlight (climate change or something running out, use of antibiotics/pesticides)
why is genetic variation important for evolution
variation due to environmental factors will not pass on to offspring
what does a mutation cause
a bacterium/insect to develop resistance to a particular antibiotic/pesticide which causes variation in the population
how can resistance occur in bacteria
overuse of antibiotics, misusing them (not taking a full course), using them on live stock
how did pesticides cause an endangered species
- pesticide used on crops
- resulted in resistance to DDT in insects due to natural selection
- small birds ate insects and this built up the food chain-more concentrated
- perigrine falcons couldn’t lay eggs- too fragile and shattered
- became endangered species
define variation
the presence of variety-differences between individuals
define intraspecific variation
variation between members of the same species
define interspecific variation
differences between species
define discontinuous variation
where there are distinct categories and nothing in between
examples of discontinuous variation
gender
some bacteria have flagella others don’t
human blood groups
whether you can roll your tongue
It is monogenetic (controlled by one gene)
defame continuous variation
variation where there are two extremes and a full range in between
examples of continuous variation
-height in humans
-length of leaves on oak tree
-length of stalk of a toadstool
-number of flagella on bacteria
-body mass
-intelligence
this variation is polygenetic (controlled by a variety of genes)
when would you use standard deviation and how would you interpret it
to measure the amount of variation or spread from the mean
low standard deviation indicates narrow range and greater reliability
high standard deviation indicates large range and lower reliability
when would you use the T test and how do you interpret it
test used to compare two means null hypothesis- no significant difference between the means of 2 sets we have to accept or reject if our value is lower, accept if our value is higher, reject
when would you use spearman’s rank correlation
used to consider the relationship between two sets of data
tells whether two sets of data are correlated
lower value than critical value=no relationship=accept null hypothesis
define adaptation
a characteristic that enhances survival in the habitat
what will a well adapted organisms be able to do
- find enough food + water
- gather enough nutrients
- defend itself from predators and disease
- survive physical conditions of its environment
- respond to changes in the environment
- have sufficient energy to allow successful reproduction
define convergent evolution
the process whereby organisms not closely related independently evolve similar traits as a result of being adapted to similar environments
what is marram grass
specialised plant adapted to living on sand dunes where there is little water available
anatomical adaptations of marram grass
- long roots which spread over wide area- reach deep underground and absorb water
- leaves are curled, lower epidermis covered in hair and folded to create pits- reduces air movement and loss of water vapour
- low density of stomata, leaf covered in thick waxy cuticle- reduces evaporation of water from cells
behavioural adaptations of marram grass
responds to shortage of water by rolling leaf tight and closing stomata
when covered by sand, it will grow to reach sunlight
physiological/ biochemical adaptations of marram grass
- ability to roll leaf- tighter when less water available
- guard cells open and close stomata
- not salt tolerant so maintains water potential lower than other plants
