Biology2

• Are adaptations that organisms have so they can tolerate extreme conditions - like very high or low pH or temperature.
• Extremophiles are organisms that are adapted to live in seriously extreme conditions - like super hot volcanic vents or at high pressure on the sea bed.

Some examples of organisms with adaptations that help them survive in harsh conditions are:

• Extremophile Bacteria which live in very hot environments - they have enzymes that work best at a much higher optimum temperature than enzymes from other organisms, as extremophile bacteria have enzymes that can function normally at temperatures that would denature enzymes from other organisms. E.g. Thermus thermophilus grows best in environments with temperatures around 65 degrees celcius.
• Organisms living in very cold environments may have antifreeze proteins which interfere with the formations and growth of ice crystals in the cells, stopping the cells from being damaged by ice.

• Anatomical adaptations are features of an organism's anatomy(body structure) that help it to survive.

Anatomical adaptations to the cold can be:

• Having a thick coat/ layer of blubber to insulate the body and trap heat in.
• Having a smaller surface area to volume ratio(large size and compact body shape) to reduce heat loss, as less body heat can be lost through the surface of the skin. Larger organisms lose less heat to their surroundings than small organisms because they have a smaller surface area to volume ratio. Small objects havea larger surface area to volume ratios compared to large objects.
• Having a counter-current heat exchange system(which penguins have) where they have blood vessels close to each other in which the blood flows in opposite directions - one flowing to the body and one flowing to the feet- as the warm blood is flowing through the arteries to the feet the heat is transferred to the vein which returns warm blood to the heart, meaning the feet stay cold but cold blood is stopped from cooling down the rest of the body.

• Migration - many species migrate to warmer climates during winter months so theycan avoid having to deal with the cold conditions.
• Hibernation - other species hibernate during winter months, which saves energy as the animal doesn't have to find food or keep itself warm as they would when active.
• ||||||||||||Huddling - some pecies huddle together to keep warm (like penguins do).||||||||||||

Anatomical Adaptations that increase heat loss involve:

• Having a large surface area to volume ratio which allows them to lose more body heat to their surroundings.
• Having large ears, also increase the animal's surface are to volume ratio, helping them lose heat. Large thin ears allow more blood to flow near the surface of the skin, so more heat can be radiated to the surroundings. 
• Storing fat in just one part of the body(like camels storing fat in their hump) stops the rest of the body from being too well insulated and allows heat to be lost more easily.

Behavioural adaptations that increase heat loss and reduce heat gain are:

• Spending time in shade or underground - this minimises the amount of heat their body gains form the surroundings.
• Being active at night when it is much cooler - also reduces heat gain.
• Bathing in water - this increases heat loss, as when the water evaporates, it transfers heat from the skin to the surroundings, cooling the animal down.

• Have a small rounded shape -  which gives them a small surface area to volume ratio to minimise the amount of water lost to the surroundings.
• Having a thick waxy cuticle layer and spines instead of leaves - reduces water loss.
• Storing water in stems -  which allows them to survive times of extreme drought.
• Having shallow, but very e x t e n s i v e roots - this ensures water is absorbed quickly over a large area.

• Having specialised kidneys - allows them to produce very concentrated urine with a very low water content.
• Having no sweat glands - prevents them from losing water through sweating.
• Spending more time underground - as the air contains more moisture than on the surface.

What he knew:

• Organisms in a species had shown wide variation.
• Organisms compete for limited resources in an ecosystem.

What he concluded:

• Survival of the fittest - organisms that are best adapated(fittest) would be more successful competitors and so would be more likely to survive.
• These organisms that have survived are then more likely to reproduce and pass on the adaptations that made them successful to their offspring. If organisms are less well adapted then they would be less likely to survive and reproduce, so are less likely to pass on their characteristics to the next generation.
• Over time, these successful adaptations become more common in the population and the species change(evolve).

• Back when Darwin told his theory, he didn't have the evidence to show why new chracteristics appeared or how individual organisms passed on beneficial adaptations to their offspring. This is because DNA had only been dicovered 50 years after Darwin's theory was published.

We now know:

• Adaptations are controlled by genes.
• New adaptations have formed due to mutations(changes in DNA).
• Successful adaptations are passed onto future generations in the genes that the parents contribute to their offspring.

• Speciation - is when organisms change so much over a long period of time due to natural selection that a completely new species is formed.
• Speciation occurs when populations of the same species change enough to become reproductively isolated (meaning they can't interbreed to produce fertile offspring).
• Geographical Isolation can cause reproductive isolation. This can be due to a physical barrier which divides a population of a species (for example, a river changes its course, so the two new populations are now unable to mix). As different mutations create different new features in the two groups of organisms, natural selection can work on the new features so that the beneficial ones can spread through eahc of the populations. Also, due to the conditions on each side of the barrier being slightly different, the beneficial features will be different for each population. Eventually, individuals from the two populations will have such different features that they will be unable to breed together to produce a fertile offspring. They will have become reproductively isolated and the two groups will be separate species.  

• It went against common religious beliefs about how life developed as it was the first plausible explanation for our existence without a Creator(God). This led to a bad reaction from religious authorities who ridiculed his ideas.
• Darwin was unable to explain why new, useful characteristics appeared and why they were inherited.
• There was not enough evidence to convince many scientists as not many other studies had been done into how organisms change over time.

Lamarck's argument:

• If a characteristic was used a lot by an animal, then it would become more developed.
• These acquired characteristics would then be passed onto the animal's offspring.

Why Lamarck's Theory was rejected:

• People eventually conclued that acquired characteristics do not have a genteic basis, so they cannot be passed onto the next generation.

• The theory has been debated and tested by a wide range of scientists and no one has been able to conclusively prove that the theory is wrong.
• The theory offers a plausible explanation for so many observations of plants and animals, like their physical characteristics and behavioural patterns.

• Carbon Dioxide is absorbed from the air when plants photosynthesise, coverting carbon from CO2 to sugars that the plant can incorporate into other carbohydrates as well as fats and proteins.
• These carbon compounds in the plant are then passed along to animals in a food chain/web that eat the plants.
• Both the plant and animal respire while they are alive, so releases CO2 back into the air.
• When plants and animals die and decay, they are broken down by bacteria and fungi in the soil. These decomposers then release CO2 back into the air by respiration as they break down the material.
• After millions of years, material from dead plants and animals can form fossil fuels like coal and oil. When these fossil fuels are burned CO2 i released back into the air. 

In waterlogged soils:

• recycling of carbon(and other nutrients) take longer in waterlogged soils than in well-drained soils. This is due to the bacteria and fungi that decompose organic material usually needing oxygen to respire and produce energy. However, waterogged soils do not have much oxygen so the decomposers have less energy and so work more slowly.

In acidic soils:

• Nutrient recycling also takes longer in highly acidic soils than in neutral soils. This is due to the extremes of pH slowing down the reproduction of decomposers or kill them.

• As millions of species of marine organisms makes shells made of carbonates, when these organisms die, the shells fall to the ocean floor, eventually forming limestone rocks. The carbon in these rocks returns to the atmosphere as CO2 during volcanic eruptions or when the rocks are weathered down.
• The  oceans can also absorb large amounts of CO2, acting as huge stores of carbon called 'carbon sinks'.

• Decomposers - decompose proteins and urea and turn them into ammonia.
• Nitrifying bacteria - turn ammonia in decaying matter into nitrates
• Denitrifing bacteria - turn nitrates back into N2 gas.
• Nitrogen-fixing bacteria - turn atmospheric N2 into nitrogen compounds that the plant can use.

Plants get nitrogen from the soil so need the nitrogen in the air to convert to nitrates before the plants can use it. These nitrogen compounds are then passed along food chains and webs as animal eat the plants and each other.

Decomposers: such as bacteria and fungi in the soil, break down proteins in rotting plants and animals, and urea in animal waste, into ammonia, returning nitrogen compounds into the soil(recycling the nitrogen in organisms).

Nitrogen fixing bacteria: lives in the soil. Others live in nodules on the roots of legume plants- like peas and beans- which is why legume plants are good at putting nitrogen back into the soil. Plants have a mutualitic relationship with bacteria as the bacteria gets the food(sugars) from the plant and the plant gets nitrogen compounds from the bacteria to make proteins.

• Nitrogen in the air is converted into nitrates that the plant can use by either nitrogen fixing bacteria or lightening(as a bolt of lightening has so much energy that its enough to make nitrogen react with oxygen in the air to give nitrates).
• The Haber process converts nitrogen gas into ammonia used in fertilisers. The ammonia is then converted into nitrates by nitrifying bacteria in the soil.
• The plant aborbs nitrates from the soil, using them to make proteins.
• The plant can be eaten by an animal which is then decomposed. Their urea is also decomposed to make ammonia. This is then converted to nitrates in the soil by nitrifing bacteria.
• Denitrifying bacteria then converts nitrates into nitrogen gas back into the atmosphere.

• When the birth rate is higher than the death rate, the population increases.
• The increase in population is means there are more resources being used up and more pollution being produced.
• The higher standard of living in more developed countries are demanding more resources. They are a small portion of the world's population but cause a large portion of pollution.
• human population is rising exponentially(increasing very quickly).

Global Warming: When fossil fuels are burned, large amounts of carbon dioxide are released. It being a greenhouse gas means it traps heat in the atmosphere, causing global temperature to rise. Scientists predicted that the rising global temperature would mean that sea levels will rise, weather will becoe less predictable and agriculture output will fall.

Acid Rain: When fossil fuels and waste materials containing sulphur are burned, they release sulphur dioxide which reacts with water in the atmosphere, forming sulphuric acid that falls as acid rain. Acid rain damages soils, can kill trees, can cause lakes to become acidic(which means the lake's ecosystem is in danger as many orgamisms are sensitive to changes in pH and cannot survive in very acidic conditions), it also damages limestone buildings and statues.

Ozone Depletion: CFC's(which were used in aerosols, fridges, air-conditioning units and polystyrene foam) broke down ozone in the upper atmosphere which allowed more harmful UV rays to reach the earth's surface. This exposure to more UV rays wil increase the risk of skin cancer and kill plankton in the sea- as plankton are at the bottom of the food chain, it will have a big effect on the sea's ecosystem- and scientists predicted that fish levels will drops so there is less food for us to eat.

Are used to tell if an area is polluted or not.

Species that cannot survive in polluted conditions:

• Lichens - are used to monitor air qualiy. If the air is cleaner then the greater iversity of lichens survive. This is because lichens are damages by pollution.
• Mayfly Larvae - are used to monitor air quality. The cleaner the water is, the more mayfly larvae survive. This is because they cannot survive in polluted water.

Species that are adapted to live in polluted conditions:

• Water lice
• Rat-tailed maggots
• Sludgeworms
• Rat-tailed maggots and sludgeworms indicate a very high level of pollution.

By using indicator species:

• Doing a survey on which species are present or absent in an area is a quick way to tell whether an area is polluted or not and how polluted the area is.
• Counting the number of times an indicator species occurs in an area gives a numerical value that allow measurements from different areas to be compared so you know how polluted an area is.

By measuring pollution directly:

• Using sensitive instruments that measure the concentration of chemical pollutants such as; carbon dioxide or sulphur dioxide in samples of air or water.
• Using satellite data to indiate pollutant level, e.g. satellites can show whether the ozone layer is thin or absent, whcih is linked to the CFC level.

Living methods (indicator species):

(A): quick, cheap and easy way to see whether an area is polluted or not. No expensive equipment or highly trained workers required.

(D): Living methods are not always reliable as other factors (like tempereture for examples) which can influence the survival of indicator species.

Non-living methods:

(A):Directly measuring pollutants gives reliable, numerical data that is easy to compare between different sites.

(A): You can identify the exact pollutants.

(D): may require more expensive equipment and trained workers.

Endangered species have a low number left in the wild and are in danger of becoming extinct(none left).

If these factors fall below a critical level, species are at risk of extinction:

• If the number of habitats fall, organisms will find it difficult to find resources like food and shelter as there aren't enough habitats to support them.
• If the number of individuals fall in a species, it will become difficult to find mates and there won't be much genetic variation in the population.
• If the genetic variation falls(number of different alleles in a population falls), a species is less likely to be able to adapt to changes in the environment or survive the appearance of a new diesease.

• Are designed to help save endangered plants and animals.
• Involves protecting habitats, creating artificial environments and captive breeding.

To evaluate conservative programmes there needs to be:

• Genetic Variation - should have enough genetic variation in a species to survive appearances of new dieseases and to cope with environmental change.
• Viability of populations - populations should be able to reproduce so must contain both males and females of reproductive age and should be large enough to prevent related individuals from breeding together(inbreeding)as this reduces genetic variation.
• Available habitats - plenty of suitable habitats should be available as the right type of habitat is important if the organisms being conserved are specialists.
• Interaction between species - species should interact with each other as they would in their natural environment.

• Protect the human food supply - as over-fishing has greatly reduced fish stock's in the world's oceans, conservation programmes can ensure future generations will have fish to eat.
• Ensure minimal damage to food chains - conserving a species would mean that if a species is not going to become extinct then organisms that feed on or are eaten by this species will not be affected so the food chain will nt be affected, helping others in the food chain to survive.
• Provide future medicines - as today's medicines come from plants, undiscovered plant species may contain new medicinal chemicals. If they become extinct - possibly due to rainforest destruction - we may miss out on valuable medicines.
• Cultural Aspects - Individual species might be important ina nation's or area's cultural heritage. For example,the bald eagles is conserved in the USA as it is regarded as a national symbol.

Sustainable Development - providing for the needs of today's increasing population without harming the environment.

• For sustainable development there needs to be cooperation locally, nationally and internationally.

What is being done to promote sustainable development:

• Fishing quotas have been introduced to prevent particular fish from becoming extinct in certain areas so they'll be around in years.
• Laws that are insisting that logging companies plant new trees to replace those that have been taken down to make the production of wood and paper sustainable.

Why we need sustainable development: As the population increases, we will be needing to produce more food and so we'll need more farmland, we will be using up more energy(which mostly comes from fossils fuels) are running out rapidly so we'll need to find an alternative energy source, we'll also be producing more waste so it will all need to be put somewhere as a lot of it is polluting the Earth.

Whales:

• used to make money, so they have commercial value whether they are alive or dead.
• are a tourist attraction
• used to make cosmetics from a wacy substance in their intestines.
• their meat and oil can be used.

The International Whaling Commission(IWC) had tried to get nations to agree to restrict whale but found it difficult. In 1982 the member nations had declared to stop whaling with the only exception being Norway that could still catch whales. Taking a small number of whales(culling) for scientific research  is allowed for Japan, Iceland and Faroe Islands. However, it is hard to whethr countries are sticking to the agreement an eve if anyone is caught the IWC doesn't have the authority to enforce any kind of punishement, so a lot of illegal whaling still goes on.

• They don't have much space and are used for entertainment. Some people think that it's wrong that whales lose their freedom and would be much happier in the wild, although captive whales do raise awareness of animals and their problems.
• Captive breeding programmes allow whales to be bred in numbers and released back into the wild.
• Research on captive whales can help us to understand their needs better to help conservation. However there is still a lot that we do not fully understand - for example, whake communication, their migration patterns and how they survive in very deep water.