Classification and Evolution Flashcards
Classification
The process of sorting living things into groups of similar organisms. It reflects how closely related they are and evolutionary relationships
Taxonomy
The study of the principles behind classification
- study of the differences between species (physical + genetic)
Phylogeny
The study of the evolutionary relationships between organisms, the study of how closely related they are
Why we classify organisms
- identify species
- predict characteristics
- find evolutionary links
8 taxonomic groups used for classification
Domain Largest
Kingdom
Phylum
Class Decreasing variation
Order
Family
Genus
Species Smallest
Binomial nomenclature
2 terms are used to denote a species of living organism
First once indicates genus, and the second one is species
E.g. Homo sapiens
Morphological features
- physical characteristics
- reproductive structures
- observable traits
Heterotrophic feeders
Eat and digest other organisms
Autotrophic feeders
Use photosynthesis to make own food
Saprotrophic feeders
Digest other organisms outside the body (using enzymes)
How many kingdoms are there
5
What are the 5 kingdoms
- animals
- plants
- fungi
- protoctista
- prokaryotes
Characteristics of each kingdom
Animals- eukaryotes, multicellular, heterotrophic feeders, no cell walls, fertilised eggs develop into blastula (multicellular organisms), move freely
Plants- eurkaryotes, multicellular, autotrophic feeders, cellulose cell wall, contain chlorophyll
Fungi- eukaryotes, mostly multicellular (yeast-unicellular), Saprotrophic feeders, chitin cell wall, reproduce with spores, mycelium made of hyphae
Protoctista- eukaryotes, mostly single celled, autotrophic & Saprotrophic feeders, variety of different forms- don’t fit into any other kingdoms, display features of multiple kingdoms
Prokaryotes- no membrane bound organelles, smaller 70s ribosomes, smaller than eukaryotes, may be free living or parasitic
no nucleus- loop of naked DNA, no histones
How many domains are there
3
What are the 3 domains
- bacteria
- archaea
- eukarya
Characteristics of each domain
Bacteria
- 70s ribosomes
- no nucleus- prokaryotic
Archaea
- prokaryotes- have no nucleus
- extremophile
Eukarya
- multicellular
- animal, fungi, plants
- protists with cilia, protists with flagella
Who introduced 6 kingdoms classification and what did they add
Carl Woese
- split prokaryotes into archaebacteria and eubacteria
Standard deviation
• used to measure how spread out a set of data is
• The higher the standard deviation, the more spread out the data is
• E.g. populations with large amounts of variation will have a large standard deviation
high SD= wider curve
low SD= tall curve
Standard deviation formula
Phylogeny
The evolutionary relationships between organisms
Advantages of phylogenic trees
- doesn’t require scientists to put organisms into groups that they may not fit perfectly into
- Linnaeus classification can be misleading
- Linnaean classification cannot be done without reference to phylogeny
- quantifiable
Disadvantages of phylogenetic trees
- extinct species are not considered
- no timing of events available
- can’t include prokaryotic species
Evidence for evolution (4)
- palaeontology
- molecular
- homologous structure
- antibiotic resistance
Evidence: palaeontology
- Fossils show that organisms have changed over time
- Methods such as carbon dating can be used to work out how old fossils are
- The oldest rocks contain the simplest species
- Ecological links, plants before animals consistent with animals needing plants to survive
- The fossil record shows many organisms that no longer exist but were intermediates between the oldest common ancestors and modern species
Problems with fossil records
- fossils don’t always form
- soft tissues don’t fossilise
- many haven’t been found
Evidence: molecular
DNA extracted from fossils
• DNA found in the nucleus of cells can be sequenced and used to provide evidence of evolutionary relationships between species and how the genetic code of species has changed as they have evolved
• shows similarities between organisms if they have a similar base sequence - implies they share a common ancestor
Highly conserved molecules
• similar cytochrome C (protein needed for respiration) primary structure shows similarities between organisms- implies they share a common ancestor
• RNA and DNA
Evidence: homologous structures
Many modern animal species share a physiological similarity - the pentadactyl limb (5 ‘fingered’) suggesting that they share common ancestors (evidence for divergent evolution)
Evidence: antibiotic resistance
Due to their fast reproduction rate, bacteria can show evolution in action
- Population of bacteria with once resistant bacteria
- Bacteria die apart from the antibiotic resistant bacteria
- They reproduce and multiply with their antibiotic resistant characteristic
- Population is all resistant to bacteria
Variation
Differences in the characteristics between organisms
2 types of variation
Interspecific- variation between different species
E.g. humans, dogs
Intraspecific- variation within species
E.g dog breeds
Causes of variation
Genetic
- blood group
- skin colour
Environmental
- tattoos
Both
- weight
- height
- hair colour
- sun tan
Causes of genetic variation
- alleles- e.g. dominant or recessive, homo or heterozygous
- mutations- change in DNA sequence
- meiosis- independent assortment and crossing over
- sexual reproduction- offspring are not clones
- chance- random fertilisation- many gametes are produced
Causes of environmental variation
- lifestyle
- food + water availability
- predators
- light
- temperature
- humidity
- carbon dioxide conc
- education
Continuous variation
Variation where the given characteristic can take any value within a range
E.g. height and weight of plants
- plotted as a histogram using frequency distributions
Discontinuous variation
Variation where the given characteristic can take a set value- there are no in between values
E.g. blood group, sex, bacterial shape
- plotted as a bar chart or pie chart
Adaptation
A feature that enhances survival and long term reproductive success of an organism
- Anatomical
- Behavioural
- Physiological
Natural selection
Selection by the environment of individuals that show certain favourable variations. These individuals will survive and reproduce and pass on their variations to the next generation
Speciation
The formation of a new species from a pre existing one
Anatomical adaptations
- body covering
- camouflage
- teeth
- mimicry
Example: marram grass
Xerophyte
- curled leaves- reduces SA and protects from wind
- hairs- trap humidity
- stomata sunken in pits- increases humidity and protects from wind
- thick waxy cuticle- reduces evaporation
Behavioural adaptations
- survival behaviours
- courtship
- seasonal behaviour e.g. migration or hibernation
2 categories of behavioural adaptations:
- innate: ability is inherited. Ways for organisms to survive in the environment they live in
- learned behaviour- experiential or observation of other normals
Physiological adaptations
E.g. reflexes, blinking, temperature regulation
• poison production- kill prey/avoid predators
• Antibiotic production- bacteria survival mechanism to kill off others in surrounding areas
• Water holding
Analogous structure- structure that have adapted to perform the same function but have a different origin
Homologous structure- appear different but have the same underlying structure
