Classification Flashcards
What do we call each group in the classification system?
Taxa
What is domain, and what are three domains called?
Highest taxonomic rank and broadest way to classify organisms
- Archaea ( ancient, extremophiles )
- Eubacteria - unicellular & no nucleus
- Eukaryotae - eukaryotes with membrane bound organelles and true nucleus
List the classification system with the anagram
Did king Philip come over for great sphagetti
Domain Kingdom Phlyum Class Order Family Genus Species
What does phylum, class and order mean?
Phylum = body plan Class = general traits Order = additional info
What are the 5 kingdoms?
Eukaryotes which possess a nucleus fall into
- animalia
- plantae
- fungi
- protoctista
Single celled organism with no nucleus fall into
- prokaryotae
What is autotrophic and heterotrophic? What is saprophytic?
Protists have this feature - when autotrophic, gain nutrients by photosynthesis. When heterotrophic, gain nutrients by digesting and absorbing food
Fungi have this feature - they feed on decaying matter
Why do we classify organisms?
- identify species easily
- for convenience and to make the study of living things more manageable
- predict characteristics of organisms
- find evolutionary links and see relationships between species ( eg if in same genus, how closely related they are )
What is the pattern in the classification system?
As the groups get smaller, there are more similarities between species in each group.
How do we name organisms ( i.e binomial nomenclature with the binomial system )? What does the same genus tell us?
First name = genus
Second name = species
Genus is capital, species has no capital
We underline the entire name to show it is Latin
Same genus tell us that 2 organisms are closely related as a genus is a group of closely related species
How is a common ancestor represented on the tree?
It is the point where the branches come off.
Who developed the classification system?
Carolus Linnaeus in the 1700s
What does a phylogenetic tree show?
- shows evolutionary relationships ( eg : on tip, 2 species will be closely related )
- can share a recent common ancestor
- phylogeny is derived from the same point ( i.e the tree starts from a single point )
- shows evolutionary timeline ( i.e starts from the origin of time with the common ancestor, the original species
- the branches are extinct mammals that existed in the past - the tips are DESCENDANTS of extinct
What does monophyletic mean?
They belong to the same phylogenetic group and share a recent common ancestor - eg the branches of human and gorilla and they evolved from the same species
What is phylogeny? What is phylogenetic classification?
Phylogeny = evolutionary relationships between organisms
Phylogenetic classification = species are arranged into groups according to evolutionary relationships
Explain the phylogenetic tree in terms of time
The further up the tree, the more recent the common ancestors are. The tree goes down from present to past.
Explain how comparative biochemistry can be used as evidence for evolution
We can compare the differences and similarities in amino acid sequences of cytochromes of different organisms. Important molecules are also highly conserved ( eg with important proteins and enzymes ) if they have an important function ( eg survival of reactions )
What can we deduce from patterns in amino acids?
AA sequence in cytochrome same = species are closely related and same DNA base sequence
AA sequence in cytochrome different = less closely related and further evolutionary relationship
Where do we find the cytochrome c chemical?
This protein is found in the mitochondria of living organisms used in respiration.
Explain how DNA sequences can be used to classify species
Most accurate
More similar sequence in part of DNA = more closely related
Differences = less closely related and evolved separately for a long time
How can palaeontology be used as evidence for evolution?
Fossils are animal and plant remains that are preserved in rocks. This is the study of fossils by looking at differences and similarities between them.
Mark scheme points :
- show how organisms have changed overtime
- methods of dating to support this
- many fossil organisms do not exist anymore
- simple landforms can evolve into more complex ones
- animals need plants to survive
- see how closely related organisms are based on similarities and differences in structure
- find if living organisms are related to certain extinct organisms ( eg if fossils extinct, can see descendants )
What is a problem with palaeontology?
Incomplete record of fossils
- typically discovered by accident
- soft bodied and decompose too quickly
- many undiscovered underground or destroyed by earths movements ( volcanoes, earthquakes etc )
How can comparative anatomy used as evidence for evolution?
Looking at similarities and differences in anatomical structures ( for eg : homologous structures - appear to be different but have same underlying structure )
We can therefore evidence divergent evolution ( different species with a common ancestor evolve with different features - become different overtime. )
What is variation, and what is interpsecific variation?
Variation is the differences in characteristics of individuals. Interspecific variation is variation between species. ( eg eye colour, skin colour )
What is intraspecific variation?
Variation between MEMBERS of the SAME species
Explain how variation is caused by inheritance ( genetic )
We inherit a combination of alleles, so this creates variation due to differences in genes or alleles. Alleles are different forms of the same genes
What is discontinuous variation?
Two or more discrete categories with no intermediate ( in between ) values.
Qualitative
Blood groups, gender
( MS : effect of a few genes, little environmental effect )
Caused by genetic, normally regulated by a single gene
Members of each species is evenly distributed or more than one type than other
Shown on bar or pie chart
What is continuous variation?
It can take any intermediate value in a range between two extremes. ( MS : range of intermediate values ). It is controlled by more than one gene and influenced by environment. ( MS : effect of genes and environment). No defined categories
shows RANGE of characteristics
Quantitative
No of individuals at extremes is low, most individuals near mean value
Height, length, weight, psychological measurements like reaction rate and heart rate
Plotted in histograms with bell shaped curve ( symmetrical around the mean ) called the NORMAL DISTRIBUTION CURVE
What is natural selection?
Process that leads to evolution
Results in species being better adapted to environment, more chance of survival and therefore more likely to reproduce
Adaptations are anatomical ( structural ), psychological or behavioural
What other factor causes variation? Give an example of a combined effect of variation?
Environmental
Caused by both environmental and genetic factor
Eg tall height due to diet but may have inherited short height genes
Explain natural selection
1) alleles for a gene are made by random mutations that are pre existing
2) this creates intraspecific variation between individuals of species
3) Selection pressures are factors that affect an organism’s chances of survival ( predation, competition etc ) or reproductive success ( ability to produce fertile offspring ) - eg lack of competition or pray
So when resources are scarce, the environment selects characteristics that give advantage - creates SELECTION PRESSURE
4) individuals which are best adapted to a selection pressure and with the allele for ——— have an increased chance of survival and reproducing ( survival of the fittest ) .
5)Their advantageous
allele/characteristic will pass onto offspring
6) over many generations, frequency of allele increases in population through evolution. There is a higher proportion of individuals with advantageous characteristic. Overtime, organisms are well adapted to environment
What is the purpose of pesticides?
Chemicals to kill pests
Therefore protect crops from damage and prevent transmission of disease by vectors
Give examples of evolution after natural selection
Pesticide resistance :
When pesticides are applied, they cause a strong selection pressure. Susceptible will die and those with form of resistance survive, reproduce and pass on resistance until entire population is resistant.
MRSA resistance to antibiotics :
When DNA replicates, it is altered and bacteria therefore dies. Mutation in MRSA causes resistance
Peppered moths
Sheep blowflies
Explain the features of the prokaryotae
- the cells are smaller and the ribosomes are smaller ( 70s )
- no nucleus
- naked DNA not associated with histone proteins
- loop of DNA not arranged in linear chromosomes
- no membrane bound organelles
- heterotrophic and autotrophic
FREE LIVING OR PARASITIC
Explain the feature of protocista
- eukaryotic
- single celled ( some algae is multicellular )
- plant or animal like features
- mostly free living
- autotrophic or heterotrophic nutrition
Explain the features of fungi
- eukaryotic
- single cells ( yeast ) or mycelium ( consists of hyphae )
- walls made of chitin
- multinucleate cytoplasm
- heterotrophic
- free-living and saprophytic
Explain the features of animalia and plantae
- multicellular
- eukaryotic
Plants - cellulose cell wall
Animals - free to move around
Plants - autotrophic
Animals - heterotrophic
How were living things previously classified?
Traditionally, they were classified by observable features. For eg, arisostle divded living things into those that live and move on land, in water and move through air.
What is a species?
A group of similar organisms within the same niche which interbreed to produce fertile offspring. The phylogenetic definition would be a group of individual organism which are similar in appearance, anatomy, physiology, biochemistry and genetics.
Niche = the role an organism plays in the community
What is adaptation?
A characteristic ( i.e variation ) that increases chances of survival in a habitat.
Explain what is meant by anatomical
adaptation, and give examples
Structural / physical features ( internal and external )
Eg in mammals : Body covering Camouflage Mimicry Teeth
Eg in plants :
Long roots to reach water deep underground
Waxy cuticle
Explain what is meant by behaviour adaptation
Aspect of behaviour of an organism that helps it survive in the conditions it lives in
Eg seasonally, some organisms migrate to better climates where conditions are more favourable
Courtship to attract mates
Survival behaviours where act dead to detract predators
Explain what is meant by physiological adaptation
One that ensures the correct functioning of cell processes
Eg :
Poison production
Antibiotic production
Water holding
Why do moles show convergent evolution? Give examples of their similar features
This is when unrelated organisms develop similar structures traits ( therefore, perform the same function - anologies )
Example : placental and marsupial moles
They both have :
- small eyes
- short fur and tail
- large claws on front legs
- cylindrical body
What are homologies?
Structure similarities which were present in a common ancestor
What are the anotomical adaptations of marram grass?
Leaves are rolled to reduce the exposed surface area and increase humidity - reduces water potential vapour gradient
Hairs on the inside trap moist air
Thick waxy cuticle to reduce evaporation
Sunken stomata on the inside of the leaf - less likely to open and lose water
What is a mole and what are the 2 different types?
A mole is a burrowing animal that feeds on small animals in the soil.
They show CONVERGENT evolution
Marsupial moles develop in the uterus and enter and leave the marsupium ( poach ) when an embryo. Typically in Australia
Placental moles live in the placenta. The placenta connects the embryo to its mothers circulatory system in the uterus to NOURISH the embryo. Develop by suckling milk
Their common ancestor was probably NOT mole - like ; developed characteristics to suit environment they live in
What are the behavioural adaptations of marram grass?
A shortage of water causes the lead to roll more tightly and closes stomata to reduce evaporation
What are the physiological adaptations of Mariam grass?
There is a tighter rolling of leaves to reduce transpiration when hinge cells lose turgidity and change shape.
Guard cells close when less turgid to close stomata.
Leaves are lignified to provide strength and prevent wilting when not turgid
What are analogous structures?
Adapted to perform the same function but have a different genetic origin ( eg tail fins of a whale and fish )
Why does convergent evolution take place?
This is because animals adapt to similar environments or similar selection pressures ( i.e live in a similar way )
How do we use phylogeny in classification?
We use phylogeny to confirm if the classification groups are correct
Advantages of phylogeny over classification
- produces a continuous tree but classification requires discrete taxonomic groups
- we can add branches, not forced to fit into groups like classification
- hierarchy of classification is misleading as it implies different groups within a rank are misleading
What causes antibiotic resistance?
Overuse and incorrect use of antibiotics
How do behavioural adaptations come about?
Innate - inherited through genes
Learned - through experience or learning from other animals
What is evolution?
Theory that describes the way organisms evolve and change overtime as a result of natural selection. It is caused by changes in the environment ( eg catastrophic event ) where the organism best adapted to the environment survives
Explain Darwin’s theory and how it supported by his observation
He suggested organisms best adapted to their environment are more likely to survive and reproduce. Therefore, offspring appear similar to their parents as characteristics are inherited by the next generation.
An observation was that he noticed a bird ( Finches ) with a beak more suited to food available was more likely to survive than a beak that wasn’t.
Therefore, more offspring and all finch population share the same characteristic.
What are the evidences that support the theory of evolution? ( Exam Q )
Similarities and differences in :
- DNA and therefore base sequence
- comparative biochemistry ( CYTOCHROME )
- amino sequence
This can imply close relationships.
What does a different branch mean?
- not closely related
- different taxonomic group
- do not share a recent common ancestor
However, phylogeny derived from the same point.
Suggest why a higher number of species have evolved in the Galapagos Islands,
compared with an area of the same size on the South American mainland. ( EQ )
Different islands have different selection pressures
Islands separated from mainland therefore no gene flow
Give 2 examples of a phenotypic continuous and discontinuous variation
Continuous :
- length
- mass
Discontinuous :
- gender
- eye colour
Explain the effects of discontinuous variation
Controlled by only genes
No/little influence by environment
Explain what cloning should result in
The offspring should be visibly different to the parent as this will show it is successfully cloned.
State the definition of the term phylogeny and explain how phylogeny is related to classification
- evolutionary relationships between organisms
- study of closeness of evolutionary relationships
- phylogeny is the basis of modern classification
- closer evolutionary relationships = closer taxonomic groups
Explain the features of the domain system
- based on differences in DNA ( and rRNA in ribosomes )
- shows that there are similarities between eukaryotic kingdoms
- groups eukaryotes together
- divides prokaryotes
Eg : prokaryotes are split into groups because bacteria and archaea are different
How do we confirm if 2 organisms belong to the same or different species?
Interbreed them to determine if the offspring are fertile
Infertile offspring = different species
What is taxonomy?
Classifying organisms due to observable features
Why samples may not be accurate?
Only small number sampled
Individuals also may not be representative of the population
What is classification?
Putting living things into groups based on similarities and differences
