B2- Understanding Our Environment

• Natural Classification systems are based on the evolutionary relationships and genetic similarities between organisms.
• Artificial Classification systems are based on appearance rather than genes, they are used to identify organisms
• King, Phylum, Class, Order, Family, Genus, Species. King Philip Came Over for Green Soup

Newly discovered species might not fit into any of the categories so it is hard to know where to place it, DNA sequencing allows us to see genetic differences between groups. From this we might see that the groups are actually very different or the groups we thought different to be close relatives

A species is a group of organisms which can interbreed to produce fertile offspring:

Why is it difficult to classify organisms?

• Asexual reproduction: This is like bacteria. Its where the organism reproduces itself by making a copy of itself, no interbreeding with another organism so they don't fit a species
• Hybrid: If you interbreed a male from one species with a female from a different species you'll get a hybrid which are usually infertile so they aren't a new species
• Evolutionary: organisms can change and evolve over time the way they've been classified might also have to change. Sometimes a group of organisms will change so much they form a new species

• Each bar on the pyramid of biomass shows the mass of living material at the stage of the food chain so how much they would weigh if you put them all together
• Measuring dry biomass can sometimes be hard though because you have to kill the organism to see how much it weighs
• Pyramids of numbers are similar to the pyramid of biomass but each bar shows a number of organisms rather than the mass
• These can be different shapes

• Energy from the sun is nearly all the the source of energy for life on Earth, plants use it to photosynthesise so this works the way through the food chain but energy however is lost at each stage because of respiration and lost to the surroundings. Material is also lost because of egestion and excretion. Waste products can become the starting points for other food chains
• You can work out the amount of energy has been lost from the energy avaliable from the previous level
• You can also calculate the efficiency of the energy transfer by doing:

efficiency=      energy avaliable to the next level

               energy that was avaliable to the previous level

A species' ecological niche is how it fits in to its ecosystem. It depends on things like where the individual lives and what they feed on

• Interspecific Competition: is where organisms compete for resources against individuals of another species
• Intraspecific Competition: is where organisms compete for resources against individuals from the same species

Parasites live off a host, they take what they need for survival without giving anything back which harms the host. Tapeworms absorb nutrients which can make them manourished and fleas are parasites which harm dogs

Mutualism is a relationship where both organisms benefit. oxpeckers live on the backs of buffalos where not only do they eat fleas, ticks and maggots off them but they alert the animal to any predator that are nearby

• Specialists: are organisms which are highly adapted to survive in a specific habitat
• Generalists: are organisms that are adapted to survive a range of different habitats

Some organisms are adapted to tolerate extreme onditions so they have to have pretty good adaptations:

• Extremophile bacteria live in very hot environments do have enzymes that work at higher optimum temperatures
• Organisms that live in very cold environments sometimes have antifreeze proteins which interfere with the formation and the growth of ice crystals in the cells which stop the cells getting damaged by ice

Anatomical Adaptations: are features of an organisms anatomy which help it survive. This could be having thick blubber or a coat or a small surface area for the cold to hit. Some have a counter-current heat exchange system which means blood vessels go to and from the feet in opposite directions which pass close together and transfer heat betwen them. This means the feet stay cold but it stops the whole body being cold

Behavioural Adaptations: many species migrate to warmer climates to avoid cold conditions or they hibernate which saves energy because it doesn't have to find food or keep itself warm, or some huddle together to keep warm like penguins

Behavioural Adaptations: animals often move into the shade to minimise the amount of heat, they can also redue their heat gain by being active at night and they can bathe in water

Anatomical Adaptations: animals adapted to survive in hot environments are small which gives them a large surface area which allows them to lose more body heat. They have large ears which help them lose heat and thin ears means more blood is near the surface and can be radiated to the surroundings, and some store fat in just one part of the body so it isn't as well insulated

DRY ENVIRONMENTS:

Desert Plants: have a small surface area which minimises water loss, they have a thick waxy layer (cuticle) to reduce water loss, they store water in their stem and have shallow but extensive roots to ensure water is absorbed

Desert Animals: have special kidneys which allows them to produce very concentrated urine, have no sweat glands and spend lots of time in burrows where the air contains more moisture

Darwin concluded that the organisms that are the best adapted would be better competitors and be more successful to survive. 'Survival of the fittest'. These then reproduce and pass on the best adaptions to their offsprings and this then evolves

His theory wasn't perfect but the discovery of DNA discovered 50 years later mean we know adaptations are controlled by genes and these are passed on through the genes

Specification happens when populations of the same species change to be become reproductively isolated which means they can't interbreed to produce fertile offspring. This can be caused by geogrpahic isolation:

• a river changes its course
• different mutations create new features in the groups of organisms
• natural selection works so they are in benefit they can spread through each population
• conditions on each side of the barrier are slightly different so they are beneficial to each population
• they will eventually have different features they won't breed together to have fertile offspring

Not everyone agreed with Darwin because it went against common religious beliefs, he couldn't explaim why new characterostcs appeared or how they were inherited and there wasn't much evidence

Lamarck had a conflicting theory....

• He argued that if a charateristic was used a lot by an animal then it would become more developed, he reckoned that these aquired characteristics could be passed on to the offspring. He said if they did alot of running they had big leg muscles. But people concluded that they don't have a genetic basis so they were unable to pass onto the offspring and it was rejected

Nowadays, Darwin's theory is accepted because the theory has been debated and tested independently by a wide range of scientists and it offers a plausible explanation for so many observations of plants and animals and behavioural patterns

The whole of the carbon cycle is powered by photosynthesis!!!!! The plants convert this into carbon dixide and sugars which go into the plants proteings and carbs. Eating plants passes the carbon to animals and both of their respiration releases carbon dioxide back into the air. The plants and animals then die and decay which are broken down by bacteria and fungi which release carbon dioxide back into the air and over millions of years the material can form fossil fuels which when burnt release carbon dioxide back into the air.

Decomposition is waterlogged and acidic soils is harder because the extremes of the pH slow down the reproduction of decomposer that kills them. There is also little oxygen so they have less energy and work slowly

• The atmoshere has 78% Nitrogen which is very unreactive but it is needed for making proteins for growth so living organsims have to get it somehow. Plants get it from the soil so nitrogen in the air has to be turned to nitrats before plants can use it. Decomposers break down proteins in rotting plants and animals and urea in animal waste into ammonia which returns the nitrogen compounds to the soil
• Nitrogen fixation is the process in turning N2 from the air into nitrogen compounds which plants can use through lightening, there is so much energy needed in this thats its enough to make nitrogen react with oxygen in the air to give nitrates and nitrogen fixing bacteria in roots and soil

Four types of Bacteria

• Decomposers- decompose proteins and urea and turn them into ammonia
• Nitrifying Bacteria- turn ammonia in decaying matter into nitrates
• Nitrogen Fixing Bacteria- turn atmospheric N2 into nitrogen compounds
• Denitrifying bacteria- turn nitrates back into N2 gas

As the population increases and we have a higher standard of living we are causing serious issues....

Global Warming: When we burn fossil fuwls we release lots of carbon dioxide which is a greenhouse gas and they trap heat in the atmosphere which causes temperatures to rise. Scientists predict that sea levels will rise, weather systems will become less predictable and agriculture will fall.

Acid Rain: When fossil fuels and waste materials are burned they produce sulfur dioxide which reacts with water in the atmospere to form sulfuric acid which falls as acid rain which damages soil, trees, it can cause lakes to become acidic and it damages limestone

Ozone Depletion: CFCs used to be used in aerosols, fridges, air-conditioning units and polystyrene which break down the ozone layer. This allows harmful UV rays to reach the Earth's surface which can increase the risk of skin cancer. They also kill plankton in the sea which will have a huge effet on the sea ecosystem and it will mean fish levels could drop

Lichens are used to monitor air quality and mayfly larvae are used to monitor water quality.

To measure pollution you can measure it directly with instruments and satellite data can be used to indicate pollutant level. We could also do a simple survey to see if a species is present or absent from an area or count how many times a an indicator species occurs in an area

Advantages and Disadvantages

Indicator Species: It is cheap, quick, easy way of saying and no need for highly trained workers. However, other factors like temperature can influence the survival so it isn't always reliable

Non- Living Methods: it gives a reliable, numerical value and the exact pollutant can be identified but it is quite expensive and you need trained workers

Many factors can cause a species to become extinct

• The number of habitats
• The number of individuals
• Genetic Variation

Conservation Programmes

• Genetic Variation
• Viability of Populations
• Avaliable habitats
• Interactions between species

Consevation Programmes benefit wildlife and humans

• Protecting the human food supply
• Ensuring minimal damage to food chains
• Providing future medicines
• Culture aspects

Many factors can cause a species to become extinct

• The number of habitats
• The number of individuals
• Genetic Variation

Conservation Programmes

• Genetic Variation
• Viability of Populations
• Avaliable habitats
• Interactions between species

Consevation Programmes benefit wildlife and humans

• Protecting the human food supply
• Ensuring minimal damage to food chains
• Providing future medicines
• Culture aspects

Sustainable development means providing for the needs of today's increasing population without harming the environment

1) Fishing quotas have een introduced to prevent some types of fish such as cod from becoming extinct in some areas, this means they will be still be around for years

2) To make the production of wood and paper sustainable there are laws insisting that logging companies plant new trees to replace those they have have chopped down

3) Education is important, if people are aware of the problems then they are more likely to help