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Biological classification & evolution 4.2.2 - Coggle Diagram
Biological classification & evolution 4.2.2
Class
class Insecta have;
3 body parts; head, thorax & abdomen
6 legs
class Arachinda have;
2 body parts; cephalothorax & abdomen
8 legs
Phylum
the 2 phyla in the animal system are the;
Chordata
have a nervous system & a bundle of nerves running along there back & a series of bones protecting it
Arthropoda
have a hard exoskeleton on the outside
the 8 taxonomic levels
Order
Family
Phylum
Genus
Kingdom
Species
Domain
Class
for humans;
Mammalian
Primates
Chordata
Hominidae
Animalia
Homo
Eukaryotic
H. sapiens
classification & phylogeny
Phylogeny is the evolutionary history of organisms.
It tells us who is related to who and how closely
All organisms have evolved from shared common ancestors.
The 1st branch point represents a common ancestor of the Hominidae family
Orangutang were the 1st group to diverge (evolve to become a different species from the common ancestor)
Each branch point represent another common ancestor from which another group diverged
Humans & orangutangs are more distantly related cause they diverged longer ago
Closely related species diverged away from each other more recently
Monophyletic - members of that group all arose from a common ancestor, e.g Chimps & Bonobos
the 3 domain classification
Carl Woese made big changes to the classification system in 1990
3 Domains: Archaea, Bacteria, Eukarya
Archaea (Archaebacteria)
The oldest living organisms on earth
The oldest living organisms on earth
The simplest of the bacteria; they live in extreme environments (e.g. bottom of sea/volcanic vents)
3 phyla of archaebacteria:
Halophiles (extreme salt conditions)
Thermoacidophiles (extreme temperature conditions)
Methanogens (harvest energy into methane)
Bacteria (Eubacteria)
More complex and common than archaebacteria; they live in more neutral conditions (found everywhere)
Archaea (Archaebacteria) Vs Bacteria (Eubacteria)
Bonds of the lipids are different
RNA polymerase is different - therefore different enzymes
Flagella has different structure
In bacteria there are no protein histones bound to genetic material in the bacteria
Different cell membrane structures
Different mechanisms for DNA replication & making RNA
Similarities between Archaea & Eukaryotes
Similar mechanisms for DNA replication & making RNA
Production of proteins (histones) which bind with DNA
RNA polymerase is similar - therefore similar enzymes
evidence used in classification
There’s a problem using observable features to classify, 2 unrelated species could adapt in similar ways to look similar
This is called convergent evolution
They might be classed in the same taxonomic group by mistake. — solution is to use biological molecules to help in classification
You need a molecule that is universal & has differences in its structure between organisms - best one to use is Cytochrome C
Starch & amylase are universal but there are no changes between organisms
Cytochrome C
A protein used in respiration - so every living thing has it, but it differs in different species.
You compare the amino acids sequences of Cytochrome C.
If you see the same sequence then the organisms are closely related - the more differences the less related they are.
Between a human & a rhesus monkey there is 1 different
Between a human & a dog fish there are 11 differences
Between a human & chimps there are no differences - not perfect but a general trend
DNA
You can also use DNA & the more similar the sequence the more closely related the species
the 5 kingdoms
https://docs.google.com/document/d/1BA1XHAxFUM36O3r3kbtwUCiYpsynF1N6CI1aN8kABzA/edit
the Binomial system (Carl Linnaeus)
there's a problem with using common names for things
Some organism have more than 1 common name (daddy long legs or crane fly)
Common names may change over translation into different languages
e.g. raspberries have 1 common name but 100 different species of plant
binomial means '2 names'
Uses ‘Genus’ & ‘Species’
E.g. Homo sapiens
Uses Latin as it’s a universal language
Variation
continuous variation
Continuous is controlled by many genes
discontinuous variation
discontinuous is controlled by one or a few genes.
Discontinuous variation has discreet categories so should be represented by a bar graph
variation in humans;
Variation in humans can be due to inherited factors, environmental factors or a combination or both
Inherited variation
when humans reproduce via sexual reproduction, the nuclei of of male cell & the female sex cell fuse. This cannot happen the same way twice, which makes each individual unique
Environment factors
some features are due to the conditions in a person’s surroundings, e.g. accent is just affected by environment but skin colour is due to both inherited & environmental factors
Interspecific variation = differences between species
Intraspecific variation = differences within a species
Combined effect of Genes & the environment;
You may have a ‘tall’ gene but you wont be tall if certain environmental factors like a healthy diet aren’t right
Himalayan rabbits can be dark or white depending on the temp when they were reared, temp below 20’ switch on a gene causing pigmentation.
convergent evolution
Convergent Evolution – the independent evolution of similar features in two unrelated species
e.g. an original mammal and reptile could be subjected to the same changing environmental conditionals, causing them to evolve in similar ways, such as to look like fish.
Marsupial and placental mammals are often convergent, as they are unrelated, but many have adapted to look similar. They have one main difference:
A marsupial mammal raises its new-born offspring inside an external pouch at the front or underside of their bodies
A placental mammal completes embryo development inside the mother, nourished by an organ called the placenta.
wolf
Tasmanian Wolf & Wolf:
Canine features; teeth, anatomy evolved to hunt prey and eat meat.
burrower
Marsupial mole & Placental mole:
• Cylindrical body
• Small eyes
• Strong front legs with claws
• Short fur and tail
• Tough skin on nose
climber
Spotted cuscus & Lemur:
• Claws/nails
• 5 strong digits
evidence for evolution
Cytochrome C evidence
Found in all repairing organisms, the amino acid sequence show which grains such are more closely related & can show evolutionary change
DNA evidence
The more distant species have more differences in their DNA sequences, e.g our DNA is 1.2% different in chimpanzee, 1.6% different to gorillas & 6.6% different to baboons
Fossil evidence
The horse gives us the most complete fossils evidence of evolution, the sequence of species are all very similar this shows how 1 pieces arose from the previous
problems
Not all fossils have been found
Not all organisms form fossils
Bones may be destroyed/eroded over time
Adaptation - 3 types (behavioural, anatomical & physiological)
Marram Grass (Ammophila)
Xerophyte - a plant that is able to grow where there is very low water availability
Anatomical adaptations;
Long roots - reach water deep underground.
Roots spread out - absorb more water / stabilises the plant
Curled leaves - decreases surface area exposed to wind, traps air inside, moisture builds up
Con - limits photosynthesis
Lower epidermal hairs- decreases air movement; retains water vapour close to lower epidermis.
Lower epidermis folded - Creates ‘Sunken Pits’ where stomata are located; they help trap water vapour
Low stomatal density - Fewer stomata = less water vapour lost.
Thick waxy cuticle - reduces evaporation of water from the cells inside the leaf.
Physiological/biochemical adaptations;
Hinge cells - These are found in the lower epidermis. When they lose water, they become less turgid and cause the leaf to roll up more tightly and so reduce water loss. If fully turgid they open up the leaf for better gaseous exchange for photosynthesis.
Guard cells - They close the stomata when they lose turgidity; reduces water loss
Water potential - Cells have a lower water potential than most plants; enables survival in salt water.
Lignin - Many cells are lignified; helps keep the plant upright when turgidity is lost
Behavioural adaptations:
Touching a worm causes it to rapidly withdraw into its burrow - this is a behavioural adaptation & increases the chances of survival
Adaptations in moles;
These 2 moles share similar characteristics;
Cylindrical body
Small eyes
Strong front legs with claws
Short fur & tail
Tough skin on nose
BUT they aren’t related & evolved separately - example of convergent evolutions
antibiotic resistance
This is a big advantage as they are able to survive in the host being treated with antibiotics; it lives longer and reproduces more often.
Bacteria have genetic variation because of mutations; some are naturally resistant to antibiotics
This leads to the allele for antibiotic resistance being passed on to the offspring.
MRSA (methicillin-resistant Staphylococcus aureus)
MRSA is a superbug (it causes serious wound infections); it is resistant to many antibiotics including methicillin.
It’s most common in hospitals where many antibiotics are use & patients already have weakened immune systems because they are ill
Clostridium difficile
If out harmless bacteria are killed by antibiotics then C.difficile have no competition and are also not killed by many antibiotics
This bacterium infects the digestive system; it produces a toxin that causes severe diarrhoea, fever and cramps.
preventing antibiotic resistance
Reduce use of them to prevent resistance.
Don’t prescribe for minor infections
Develop new antibiotics or modify existing ones.
Make sure that patients take all of their prescribed medication.
natural selection & evolution
how natural selection works
4 - Individuals with a selective advantage will survive and reproduce.
5 - Therefore, they pass on their advantageous characteristics.
3 - Once we have variety, the environment can ‘select’ those variations that give an advantage. This is a ‘selective pressure’ (also known as ‘selective force’).
6 - The next generation will have a higher proportion of individuals with the successful gene
2 - This creates genetic variation (intraspecific)
7 - Over time, the group of individuals of organisms becomes better adapted to their environment
1 -A mutation creates alternative versions of a gene (alleles).
Pesticide Resistance in Insects:
DDT accumulates in the fat tissues of predators’ body tissues (Bioaccumulation)
This amplifies as you go up the food chain (Biomagnification).
Some insects will become resistant through natural selection; the resistant insects are eaten by predators who get a larger dose as they eat many insects (DDT has been found in almost all organisms)
It is usually the top carnivore which dies because of this; humans are also at risk
Pesticides are chemicals designed to kill pests; DDT is a powerful insecticide
Evolution of super rats;
The rats who can tolerate the poison have a selective advantage
Most rats in the next generation will have inherited the useful genes & be resistant to the poison
Rat poison introduces a selective pressure to the environment
it selects those few who can survive the poison
The population has become adapted to the new poisonous environment
Because of mutations there exists variation in think the population (meiosis & sexual reproduction)
The surviving rats can reproduce & pass on their advantageous characteristics through their genes
