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  • Created by: l11n
  • Created on: 03-02-16 17:44


Natural classification system- Based on evoluntionary relationships and genetic similarities

Artificial classification-based on appearance rather than genes used to identify organsisms

  • Living things are divided into kingdoms
  • Kingdoms are subdivided
  • Kingdom 
  • Phylum
  • Class
  • Order
  • Family
  • Geneus - type of closely related species animals that can interbreed
  • Species
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Classification 2

Newly discovered spieces

  • Might not fit into any categories 
  • DNA sequencing allows us to see genetic differences between different groups. 
  • When this is collected we might see that they rae not as close as we thought but could be relatives

Evolutionary trees

  • You can draw evolutionary trees to show how closely related speices are.
  • They show common ancestors 
  • Studying charateristics for a large group of organsims inclused anaylsing DNA
  • Closely related species have recent common ancestors they tend to live in similar habitats 
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Species- Is a group of organsisms that can interbreed to procude fertile offspring

Asexual reproduction

  • Bacteria 
  • The organsim reproduces by making a cop of itself. 
  • There is no interbreeding with another orangism so they dont ift into the definition of a species. 


  • If you interbreed a male from one species and a female from another you get a hybrid.
  • They aren't a new species so its difficult to classify them 

Evolution is a continuous process

  • Organsims evolve over time
  • The way they've been classified might change so much it froms a new species
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Binomial system

  • Each species is given a two part name
  • The first part is about the genus 
  • The second part is about the Species
  • The system is used all around the work so that scientist have the same name for everything although they speak different languages
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Trophic level- feeding level 

  • Each pyramid of biomass shows the mass of living material usually in KG
  • The bar that is at the bttom is the first thing in the food chain 
  • To contrust a pryamid the dry biomass iof the organsisms is used. 

Pyramids of numbers

  • Each bar is the number of organisms not their mass.

eg .

A bar of pear trees can be small beacuse one pear tree can feed lots of animals but in a biomass pyramid one pear tree is alot heavier than the animals it feeds.


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Energy transfer

  • Energy from the sun is the main source of energy
  • Plants use energy from the sun to make food from photosynthesis
  • Energy lost at each stage is used for respiration 
  • Most of the energy is lost to surroundings as heat 
  • Material adn energy is lost from the food chain as waste products (egestion and excretion)
  • Waste products and uneaten parts become a starting point for other food chains.

Most biomass is lost so doesnt become biomass in the next level up.you hardly ever get more than five trophic levels because of this , energy is lost at each stage so theres not enoughtto suport the organisms after four, five stages.

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energy flow

Energy flow Effciency =              Energy avaliable to the next trophic level                                                                                      Energy that was avaliable to the previous trophic level


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Compete to survive

  • Similar organsisms are in closest competition as they copete for similar ecological niches
    • Ecological niche is how an organism fits into its ecosystem it depends on where the individuals live and what they feed on.

Types of competition 

  • Interspecific competetion - Competition between different species
  • Intraspecific competition- Comepteition bewteen the smae species
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Cycle of population

  • Population is limited depending on amount of food avaliable
  • If the population of prey increases the population of predators increases
  • When the prey decreases the preadators decrease
  • When the preadators decrease the prey increase beaucse they are not eaten as much 
  • The cycle carries on
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Parasitic and mutualistic

  • So where an orgsanism lives and its abundance(population size) is infulenced by the distribution and abundace of these species


  • Live of a host
  • Take what they need to survie without giving anthing back 
  • This harms the host
  • Win lose situation


  • A relationship where both organsisms benifit 
  • Win win situation
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  • Features that make an organsim better suited to their environment
  • Organsims that are adapted can compete better for resources
  • More likely to survive, reproduce and pass on adaptations to children 


  • Organsisms that are highly adapted to survive in specific conditions . 


  • Organsisms that are adapted to survive in a range of different habitats.
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Biochemical adaptions

  • Some organsims can tolerate exterme conditions
  • EXTREMOPHILES- Organsims that can live in seriously extreme conditions


  • Extremophiles bacteria can live in very hot conditions and can work at higher temps than enzymes from other organisms
  • Are able to function normally at temps that would denature enzymes from other organsisms


  • Organisms in very cold environments hava special antifreeze proteins
  • Proteins interfere with formation and growth of ice crystals stopping cell damage.
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Adaptations to cold weather

  • Anatomical adaptations are features of an orgasims anatomy (body structure)
    • Having a thick coat , layer of blubber, to insulate the body (trap heat)
    • Large size and compact body shape. to give small surface area to volume ratio.(this reduces heat loss as less body heat can be lost through SF of skin )
  • Animals like penguins have to stand on ice all day. 
    • Blood vessels going to and from the feet carry blood that flows in opposite directions.
    • The vessels pass close to transfer heat between them 
    • warm blood in arteries to the feet heat the cold blood returning to the heart.
    • This means the feet stay cold but the cold blood doesnt cool down the rest of the body 
  • Species also migrate to warmer climates in the winter months
  • Hibernate to save enery
  • Huddle together to keep warm
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Adaptations for hot weather

  • Animals in very hot climates stay in the shade or underground to minimise the amount of heat their bodies gain from surroundings
  • Being active at night reduces heat gain as its much cooler at night
  • Increase heat loss by bathing in water,as the water evaporates the heat transfers from the skin to the surroundings
  • Animals adapted for hot weather are normally small
    • Gives them a large surface area to volume ratio to help them lose heat
    • large thin ears allow more blood to flow near the surface of the skin so more heat from the blood can be radiated to surroudings
    • Store fat in one paret of the body, stop the body from being well insulated and allows heat to be lost easily.
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Dry environments


  • Rounded shape-Small surface area to volume ratio to minimise water loss from the surface
  • Thick waxy layer (cuticle)
  • Spines instead of leaves to reduce water loss
  • Store water in stems to allow survival in drought
  • Shallow but etensice roots to ensure water is absorbed quickly over a large area.


  • Speacialised kidneys- Produce very concentrated urine, with a very low water content
  • No sweat glands- Less water loss from sweating
  • Lots of time in an underground burrow where air contains more moisture than on the surface
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