B2

• All organisms are classified into groups:kingdom,phylum,class,order,family,genus,spieces 
• Organisms can be classified in 2 ways: 
  Artifical System: based one or two characteristics, birds that live by the sea- sea birds
  Natural System: based on evolutionary relationship, much more detailed 
• Speices:a group of organisms that can interbreed to produce fertile offspring 
• Binomial System: 1st name:Genus 2nd name:speices 

Spieces that are hard to classify:

• Bacteria:do not interbreed,reproduce asexually they cannot be classified due to this
  Hybrids:infertile so cannot be put into a spieces 

Organisms have differences and similarities for different reasons:

• 1.Ecologically related-similar because they live in the similarities 
• 2.Through evolution-organisms that live in different habitats but are still related  

Pyramids of biomass:show the dry mass of living material at each stage of the food chain 
They may look different to a pyramid of numbers if:

• the producers are very large 
• a small parasite lives on a small animal 

Pyramids of biomass are difficult to construct because: 
some organisms feed on organism from different trophic levels
Measuring the dry mass means removing all the water which will kill the organism

Energy is lost in growth however in other less useful forms: heat,egestion,excretion

Efficiency:energy used for growth
                        energy input  

Carbon Cycle(A* bits)-carbon dioxide is absorbed by oceans and marine organisms make shells made from carbonate-limestone. The carbon in limestone can return to the air through volcanic eruptions or weathering 

The Nirtogen Cycle: 

• Plants take in nitrogen as nitrates from the soil to make protein for growth 
• Decomposers return nirtogen back to the soil from dead plants,they convert protein and urea into ammonia
• A number of micoorganisms recycle nitrogen 
  •  
    •  
      •  Nitrifying bacteria:convert ammonia into nitrates 
      • Denitrifying bacteria:converts nitrates into nitrogen gas 
      • Nitrogen Fixing Bacteria: fix nitrogen gas this can happen through lightning too

Acidic conditions will slow decay down and so will water logged soils as there isn't much oxygen  

Competition: 
An ecological niche:the habitat an organism lives in,and it's role within that habitat
Interspecific:between organsims in a different spieces
Intraspecific:between organisms of the same spieces, more significant as they need the same resources due to similarities

Predator-Prey Relationships:show cylical changes in their number because when there is more prey, predators have more to eat, so their numbers increase, they eat more prey,causing prey numbers to decrease,predators strave so their numbers decrease
Predator peaks occur soon after prey peaks because it takes time for more predators to survive and reproduce

Parasitism and Mutalism:
Parasites: e.g.tape worms and fleas 
Mutalism:when both organisms benefit as a result of the relationship e.g.cleaner fish
Pea Plants have a mutalism relationship with certain bacteria, Pea plants are legumes that contain structures on the roots called nodules that contain nitrogen fixing bacteria. The bacteria converts nitrogen into nitrogen chemicals and gives some to the plant,the plant gives sugar to the bacteria from photosynthesis.  

Adapting to the cold:

• Anatomical Adaptations: excellent insulation, usually big animals with small ears, to decrease the surface area to volume ratio 
• Behaviour Adaptations:some migrate long distances to warmer areas,others slow down body proccess and hibernate
• Some organisms have biochemical adaptations like anti freeze proteins

Adapting to the hot: Organisms that survive in hot conditions-extremophiles 

• Anatomical:very little hair on the underside of their body,larger surface area to volume ratio 
• Bahavioural:panting,licking their fur,seek shade during the hotter hours of the day
• Camels:produce very concentrated urine 
• Cacti reduce water loss because their leaves have been reduced to spines, very deep roots,can store water in the stem

Specialists: very well adapted to living in a certain habitat e.g.polar bear 
Generalists:can live in several habitats e.g.rats 

The Theory: 

• Within any speices there is variation 
• Organisms produce far more young than survive, competion for limited resources 
• Those best adapted will survive, survival of the fittest
• Those that survive pass on successful adatations to the next generation 

Natural Selection may result in a new speices if different groups of organisms cannot mate for a long time, they might be prevented from mating because they live in different areas(geographical isolation), they might also be prevented due to behavioural isolation. If each group evolves differently they might over time become different enough to be classed as different speices

Mordern examples:light and dark peppered moths, resistant bacteria

Arguements over natural selection:
Darwins' theory is much more widely accepted because it explains at lot of observations and it has been discussed and tested by a lot of scientists 
Jean Baptiste de Lamarck came up with the theory called the law of aquired characteristics, as we know more about genes, this theory has been proved incorrect 

Three main types of pollution: carbon dioxide,sulfur dioxide,CFC's 

The human population is growing at an ever increasing rate=exponential rate this is because the birth rate is exceeding the death rate 
Carbon Footprint: this measure the total greenhouse gas given off by a person within a certain time

Measuring Pollution:
Indicator Organisms: they can estimate different levels of pollution by their presence 
Mayfly larva only lives in clean water so if there are mayfly larvas about the pollution is 
Water louse,bloodworm, mussels live in polluted areas of water 
Lichens only grow when the air is clean, they are not found in cities

Direct Methods of measuring pollution:oxygen probes,chemicals that measure nitrate pollution from fertillisers 
Advantages of indicator speices:cheaper,work for a long period of time,can't go wrong 
Advantages of direct methods: produce more accurate results 

Conservation:trying to preserve the variety of plants and animals and the habitat they live 
People believe conservation is important because: it protects our food supply, prevents damage to food chains, protects plants for medical uses. 
When trying to conserve a speices you have to consider important factors:

• the size of the population 
• the number of suitable habitats available 
• how much competion there is from other speices 

Whale Conservation: 
Whales are kept in captivity for research, captive breeding,entertainment
Scientists believe there is a need to kill whales to help them find out more about how they survive at extreme depths, however they can study migration patterns,communication while their alive
Sustainable Development: means taking enough resources for current while leaving enough for the future e.g. fishing quotas 
Why we need develop sustainably? Fossil fuels are running out, decrease demand for energy so we need to manage fuels like wood. We need to supply food to growing populations without destoying habitats