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OCR Biology A level Classification and Evolution (5 Kingdom (Protoctista…
OCR
Biology A level
Classification and Evolution
Classification System
King Phillip Came Over For Good Soup
Kingdom
Phylum
Class
Order
Family
Genus
Species
Why?
Identify species
To predict characteristic
To find evolutionary links
3 Domain
Eukarya
80s ribosomes
RNA polymerase contains 12 proteins (mRNA transcription)
Protoctista
Plantae
Fungi
Animalia
Archaea
70s ribosomes
RNA Polymerase of different organisms contains 8 and 10 proteins (similar to eukaryotic ribosomes )
Archaebacteria
Can live in extreme environments
Bacteria
70s ribosomes
RNA Polymerase contain 5 proteins
Eubacteria
Found in all environments
5 Kingdom
Protoctista
Mainly unicellular
Has Nucleus
Has Membrane-Bound Organelles
Some have chloroplast
Some can move using Cilia, Flagellum or amoeboid mechanisms
Fungi
Can be Unicellular or Multicellular
Has Nucleus
Has Membrane-Bound Organelles
Has Chitin Cell Wall
No chloroplast or chlorophyll
Can't move
Have a body or mycelium made of threads or hyphae
Nutrients acquired by absorption - from decaying material (Saprophytic)
Store food as Glycogen
Plantae
Multicelluar
Has Nucleus
Has Membrane-Bound Organelles
Has Chloroplasts
Has Cellulose Cell Wall
Has Chlorophyll
Doesn't Move; Some Gametes have cilia or flagellum
Animalia
Multicellular
Has Nucleus
Has Membrane-Bound Organelles
No Cell Walls
No Chloroplasts
Moves using Cilia, Flagella or Contractile Protein (like muscles)
Nutrients acquired by ingestion (heterotropic)
Food stored as Glycogen
Prokaryotae
Unicellular
No nucleus
No membrane bound organelles
Ring of 'Naked' DNA
Small Ribosomes
Evidence of evolution
Fossils
Simpler organism 's fossils are found in older rocks while more complex organism's fossils are found in recent rocks.
Shows that simple life forms evolves over time into complex ones
The sequence in which the organisms are found matches their ecological links to each other.
Plant fossils appear before animal fossils which is consistent with the fact that animals require plants to survive.
Can use fossils to study similarities to see how closely related organisms have evolved.
Allow relationships between extinct and living organism to be investigated
HOWEVER the fossil record is not complete.
Soft-bodied decompose quickly and don't have a chance to fossilise
Conditions for fossilisation and not always present
Some fossils are destroyed
Comparing anatomy
Homologous Structure
Is a structure that looks similar but may have different functions.
Comparing biochemistry of organisms
Studying the similarities and differences in the proteins and other molecules.
Variation
Interspecific
variation is between members of different species
Intraspecific
variation between organisms within a species
Causes
Genetic variation
Alleles
Genes have different alleles which produce different effects.
Individuals in a population may inherit different alleles
Mutations
If a mutation (change to the DNA sequence) occurs in somatic cells, the individual is affected
If a mutation occurs in gametes, the offspring may inherit it
Both causes variation
Meiosis
Before the nucleus divides and chromatids separate, the genetic material are mixed up by independent assortment () and crossing over ()
Leads to the offspring showing variation
Sexual reproduction
Offspring inherits alleles from each parents meaning individual is different from the parents
Chance
Its up to chance to which two genome combine
Therefore individuals can differ from their siblings.
Genetics and Environmental
Environmental variation
Plants are affected by environment more than animals because they are more mobile.
eg hydrangeas produce blue flowers in acidic soil and pink in alkali
eg scars on animals from the environment
Statistical test
Standard deviation
Measures the spread of data.
The greater the spread, the greater the Standard Deviation
s = sqrt((sum of ((x - mean)^2)) /
n-1)
Student's t test
Used to compare the means of data values of two population
Must be normally distributed and have a reliable mean
degrees of freedom = (n1 + n2) - 2
If t value is greater than the value at 0.05 on the table, reject null hypothesis?
t = (mean1 - mean2) /
sqrt((s1^2/n1) + (s2^2/n2))
Spearman's rank correlation coefficient
Used to consider the relationship between two sets of data
rs = 1 = perfect positive correlation
rs = -1 = perfect negative correlation
rs = 0 = no correlation
rs = 6 x sum of(d^2) /
n(n^2 -1)
d = difference in rank
Phylogeny
Name given to evolutionary relationship between organisms
Advantages
Can show the entire history of the species
Produces a continuous tree rather forcing them into groups like classification
Can confirm the causes that cause them to change
Can confirm classification groups are correct
