Classification and evolution

Classification

Placing organisms based off similarities

Species

Capable of breeding to produce fertile offspring

Common ancestry

Similar genes

Similar morphology

Similar biochemistry

Similar behaviour

Not fixed, can evolve, have variety across species

Taxonomy

Study of classification

Based off physical similarities

Taxa = level within taxonomy, higher taxa means less similar

Binomial naming

Universal language

Shows evolutionary relationship of species at Genus level

May be different common name for same species in different areas of the world

5 Kingdoms

Animalia

Plantae

Fungi

Protoctista

Prokaryote

Animalia

Eukaryotic

Multicellular

Motile

Heterotrophic

No cell wall

Plantae

Eukaryotic

Multicellular

Autotrophic

Cellulose cell walls

Chloroplasts with chlorophyll

Fungi

Eukaryotic

Multi or unicellular

Saprotrophic

Digest extracellularly, secreting digestive enzymes

Chitin cell walls

Made of hyphae filaments for enzyme secretion and nutrient absorption

Produce spores

Protoctista

Eukaryotic

Mainly unicellular

Auto or heterotrophic

No cell wall

Wide variety

Prokaryotic

Across 2 domains

Unicellular

Small

Autotrophic

No nucleus- loops of DNA

Peptidoglycan cell walls

No membrane bound organelles

Biochemical methods of classification

Cytochrome C- sequence of amino acid chain

DNA- sequence of nitrogenous bases

Convergent evolution

2 species adapting to the same environment but are not related at all

3 Domains

Bacteria

Archea

Eukarya

Scientific knowledge and technology improves so we find out more

Determined by rRNA and way protein synthesis occurs

All eukaryotes in same domain but different kingdoms

Prokaryotes can be in archea or bacteria

Evidence for domains

domains group all eukaryotes in eukarya domain- multiple similarities:

Nuclei

Membrane bound organelles

Linear DNA with histones

Large ribosomes ( 80s )

Darwin and Wallace

Independent work, same conclusion

Darwin Wallace theory

Observations- DW

Organisms often overproduce

Population numbers remain fairly similar

No 2 individuals are similar

Offspring look similar to parents

Deductions- DW

Must be competition

Some with better adaptations survive and reproduce

Organisms pass characteristics to offspring

Fossil evidence

Many are extinct organisms

Show change over time

Carbon dating

Can extract DNA from some

Older rocks, older fossils ( more different )

Small number of organisms fossilised and many are incomplete

Molecular evidence

Indicates presence of common ancestor

Similar species use similar molecules

Inter-specific variation

Differences between different species

Intra-specific variation

Differences within the same species

Causes of variation

Alleles- different versions of a gene which code for specific protein

Sexual reproduction ( meiosis ):

Prophase I - crossing over

Metaphase I - independent assortment

Metaphase II - independent assortment

Random fusion of gametes

New allele occasionally by mutation

Environmental variation

Differences not caused by DNA, cannot be inherited

Discontinuous variation

No environmental impacts

Only genetic effects

Qualitative

Discrete values

On a bar chart

Single or a few genes

Variation with no in-betweens

Continuous variation

Variation on a continuum

No defined categories

Quantitative

Many genes, environmental

Alleles have additive effect

Line graph or histogram

Standard deviation

Spread of data from the mean

More useful than a range of results, considers every piece of data

Small standard deviation, close to mean, little spread in data

s = standard deviation

x = individual value

lined x = mean

N = number of data points

Spearman’s rank

provides a value to determine the strength of the relationship between the variables

To see if there is correlation between two variables

Any data from smallest to largest

Measures whether data are in same order

Not valid if there are a lot of ties

Requires a null hypothesis

rs = rank coefficient

d = difference between the ranks

n = number of pairs of values

Student T-test

Compares two means to test whether there is a significant difference

Null hypothesis required, saying no difference

Degrees of freedom

Lined x = means

S²- standard deviations of first set of data squared

N- number of data points

Anatomical adaptation

Structural features

Physiological adaptation

An organisms processes

Behavioural adaptation

How an organism acts

Natural selection process

Random mutation

Genetic variation

Selection pressure

Survive and reproduce- selective advantage

Pass on mutation/allele

Allele frequency increases