4.2.2 Classification and Evolution Flashcards
Classification; taxonomic groups
Kingdom Phylum Class Order Family Genus Species
= hierarchical classification
= Linnaean classification
Why do scientists classify organisms?
- to identify species
- to predict characteristics
- to find evolutionary links
The three domains
Archaea
Bacteria
Eukarya
definition of a SPECIES
A group of organisms that are able to reproduce to produce fertile offspring
Naming organisms
Genus, species
= binomial nomenclature
The five kingdoms
Prokaryotes:
• Prokaryotae (bacteria)
Eukaryotes: • Protoctista (unicellular) • Fungi (e.g. yeast,moulds) • Plantae • Animalia
Prokaryotae
Unicellular
No nucleus or organelles
Ring of naked DNA
No visible feeding mechanism
Protoctista
Mainly unicellular
Nucleus and organelles
Some have chloroplasts
Some are sessile, some have cilia/flagella
Nutrients acquired by photosynthesis or ingestion of other organisms or parasitic
Fungi
Uni and multicellular
Nucleus and organelles
No chloroplasts
No locomotion
Body made of threads or hyphae
Nutrients acquired by absorption - saprophytic feeders
Most store food as glycogen
Plantae
Multicellular
Nucleus and organelles (chloroplasts,cellulose cell wall)
Chlorophyll
Nutrients acquired by photosynthesis - autotrophic (make own food)
Store food as starch
Animalia
Multicellular
Nucleus and organelles
No chloroplasts
Move with cilia, flagella, contractile proteins (e.g. muscle organs)
Nutrients via ingestion
Food stored as glycogen
Archaebacteria
Aka ancient bacteria
Extreme conditions (thermal vents, anaerobic conditions, acidic environments)
Eubacteria
True bacteria
All environments.
Three domain, six kingdom system
Bacteria, archaea, eukarya
Eubacteria, archae-bacteria, protoctista, plantae, fungi, animalia
Bacteria/eubacteria and archaea/archaebacteria REPLACE prokaryotes
Phylogeny
Name given to evolutionary relationships between organisms
Phylogenetics
The study of the evolutionary history of groups of organisms
Phylogenetic trees
Represents evolutionary relationships between organisms
Branched diagrams
Earliest at base
Similarities in physical and genetic make up
Much evidence gained from fossils
Advantages of phylogenetic classification
- done without reference to Linnaean classification
- classification uses phylogeny for confirmation
- continuous tree
Evidence for evolution
- palaeontology - study of fossils
- comparative anatomy
- competitive biochemistry
Palaeontology
Fossil records
Allow relationships between extricate and living organisms to be invesigated
Comparative anatomy
Homologous structures - same underlying structure
e.g. pentadactyl limb
= common ancestor
Presence of homologous structures provides evidence for divergent evolution. How diff species have evolved from a common ancestor
Comparative biochemistry
Sim/diff in proteins and other life process molecules
e.g. cytochrome c (protein in respiration and rRNA)
Changes that don’t affect molecules function are called ‘neutral’
Interspecific variation
Variation between members of different species
Intraspecific variation
Variation between organisms of the same species
Causes of variation
- an organisms genetic material
* the environment in which the organism lives
Genetic causes of variation
- alleles - inherited
- mutations - in gametes then passed on to offspring or in proteins
- meiosis - half genetic info, independent assortment and crossing over
- sexual reproduction - info from each parent
- chance - fertilisation
More variation in organisms that reproduce sexually
Blood group determined directly by genetic variation
Environmental causes of variation
Plants affected to greater degree die to lack of mobility e.g. access to sun
Characteristic determined purely by environmental variation = scars
- accident or disease
- no genetic origin
- not inherited
Environmental and genetic causes of variation
Combination
e.g. Tall genes vs poor diet
Skin colour At birth (inherited) vs exposure to sunlight
‘Nature vs nurture’
Discontinuous variation
A characteristic that can only result in certain values e.g variation cause by genetic factors, an animals sex, blood groups
e.g in microorganisms, shape of bacteria
Bar chart
Continuous variation
A characteristic that can take any value within a range
Graduation from one end to other = continuum
e.g. height and mass of plants/animals
Frequency table
Histogram
Normal distribution curves
Bell shaped curve
• mean mode median the same
• symmetrical
• most values lie close to the mean
68% within 1 s.d. of mean
95% within 2 s.d. of mean
99.7% within 3 s.d. of mean
Standard deviation
How spread out the data is
Greater = more spread
T test
Compare mean values of two sets of data
x1/2 = mean of populations 1/2 Sigma1/2 = standard deviation of p1/2 n1/2 = total no of values in samples 1/2
Null hypothesis = prediction that there’s no significant difference between populations
Spearman’s rank correlation coefficient
Two sets of data can show:
• no correlation
• +ve correlation (as one increases, the other increases)
• -ve correlation (as one increases, the other decreases)
r5 = correlation coefficient d = difference in ranks n = no of pairs of data
Adaptations
Anatomical - physical
Behavioural - inherited or learned
Physiological - internal processes
Anatomical adaptations
- body covering
- camouflage
- teeth
- mimicry
Adaptations; marram grass
- curled leaves
- hairs on inside of leaf
- sunken stomata
- thick waxy cuticle
Behavioural adaptations
• survival behaviour • courtship (attract mates) • season behaviours - migration - hibernation
Innate/instinctive = inherited Learned = learnt from experience/observation
Physiological adaptations
- poison production
- antibiotic production
- water holding
Anatomical adaptations; evidence for convergent evolution
Analogous structures = similar role but very different structure
= adapted to perform same function but have different genetic origin
Convergent evolution
= unrelated species begin to have similar traits
• similar environments
• other selection pressures
Natural selection
1) organisms show variation cause by genes
2) favourable characteristics have increased chance of survival
3) successful organisms pass advantageous characteristic allele to offspring
4) repeated every generation
5) over many generations, leads to evolution of a new species
