- Created by: lilyemma
- Created on: 16-04-17 19:34
Classification is organising living organism into groups:
- Classification systems are important in science because they help us to understanding how organisms are related (evolutionary relationship) and how they interact with eachother (ecological relationships).
- Classification systems can be natural or artificial: Natural classification systems are based on the evolutionary relationships and genetic similaries between organisms. Artificial classification systems are based on appearance rather than genes. They're used to identify organisms.
- Living things are divided into kingdoms (eg: the plant kingdom).
- The kingdoms are then subdivided into smaller and smaller groups - phylum, class, order, family, genus, species.
- A genus is a group of closely-related species - and a species is a group of organisms that can interbreed to produce fertile offspring.
- It can be difficult to classify organisms into these distinct groups though because many organisms share characteristics of multiple groups.
Classification systems change over time:
- When a classification system is created it fits everything we know so far about different groups of organisms.
- But as scientists discover new species (and learn more about the species that they've already discovered) they might have to adapt classification systems to fit their new findings:
- Newly discovered species might not really fit into any of the categories. These could be living species or newly discovered fossils, eg: the archaeopteryx fossil has features of two different classes (birds and reptiles), so it's hard to know where to place it.
- DNA sequencing allows us to see genetic differences between different groups. As this data is collected, we might find out that two groups aren't actually as closely related as we'd thought - or two groups that we thought were very different might turn out to be close.
Sorting organisms into species can be quite tricky:
- A species is a group of organisms which can interbreed to produce fertile offspring
- Classifying organsims into species isn't always straightforward - there are a few problems:
- ASEXUAL REPRODUCTION: Some organisms, such as bacteria, reproduce asexually. Asexual reproduction is where an organism reproduces by making a copy of itself. There is no interbreeding with another organism so they don't fit the definition of a species.
- HYBRIDS: If you interbreed a male from one species with a female from a different species you'll get a hybrid (if you get anything at all). For example: a mule is a cross between a donkey and a horse. But hybrids are usually infertile so they aren't new species - this makes it difficult to classify them.
- EVOLUTION IS A CONTINUOUS PROCESS: Organisms change and evolve over time, so the way they've been classified might also have to change. Sometimes a group of organisms will change so much it will form a new species - but it can be difficult to tell when this has happened.
The binomial system gives everything a two-part name:
- In the binomial system, each species is given a two part Latin name. The first part refers to the genus that the organism belongs to and the second part refers to the species. eg: humans are known as Homo sapiens; 'homo' is the genus they belong to and 'sapiens' is the species. The genus name is sometimes shortened to a capital letter and a full stop, eg: E. coli is short for Escherichia coli.
- The binomial system is pretty important - it's used by scientist all over the world.
- It means that scientists in different countries or who speaks different languages all refer to a particular species by the same name - avoiding possible confusion.
Closely related species have recent common ancestors:
- Similar species often share a recent common ancestor, so they're closely related in evolutionary terms. They often look very alike and tend to live in similar types of habitat eg: whales and dolphins
- This isn't always the case though - closely related species may look very different if they have evolved to live in different habitats, eg; llamas and camels.
- So to explain the similarities and differences between species, you have to consider how they're related in evolutionary terms AND the type of enviroment they're adapted to.
Energy Transfer and Energy Flow I
All that energy just disappears somehow...
- Energy from the Sun is the source of energy for nearly all life on Earth.
- Plants use a small percentage of the light energy from the Sun to make food during photosynthesis. This energy then works its way through the food chain as animals eat the plants and each other.
- The energy lost at each stage is used for staying alive, ie: in respiration, which powers all life processes.
- Most of this energy is eventually lost to the surroundings as heat. This is especially true for mammals and birds, whose bodies must be kept as a constant temperature which is normally higher than their surroundings.
- Material and energy are also lost from the food chain as waste products. Egestion is when food that can't be digested passes out as faeces. Excretion is when the waste product of bodily processes are released, eg: urine.
- Waste products and uneaten parts (eg:bones) can become starting points for other food chains. For example. houseflies just love to eat faeces.
Energy Transfer and Energy Flow II
- Material and energy are both lost at each stage of the food chain. This explains why you get biomass pyramids. Most of the biomass is lost and so does not become biomass in the next level up. It also explains why you hardly ever get food chains with more than about five trophic levels. So much energy is lost at each stage that there's not enough left to support more organisms after four or five stages.
- The efficiency of energy transfer can by worked out by doing:
- efficiency = energy available to the next level/energy that was available at the previous level x100
- For example: at the 1st trophic level, efficiency of energy transfwer = 10 000kJ/ 80000kJ x 100 = 12.5% efficient.
Interactions Between Organisms I
Organisms compete to survive:
- In order to survive and reproduce organisms must compete against each other for the resources that they need to live (eg: food and shelter)
- Similar organisms in the same habitat will be in the closest compe***ion because they'll be competing for similar ecological niches.
- A species' ecological 'niche' is how it fits into its ecosystem. It depends on things like where the individuals live and what they feed on.
- There are two types of compe***ion between organisms: INTERSPECIFIC COMPETITION is where organisms compete for resources against individuals of another species. INTRASPECIFIC COMPETITION is where organisms compete for resources against individuals of the same species.
- Intraspecific compe***ion often has a bigger impact on organisms than interspecific compe***ion.
- This is because individuals of the same species have exactly the same needs, so they'll compete for resources, eg: a blue *** might compete with another blue *** for food, shelter and a mate, but a blue *** and a great *** might only compete for the same food source.
Interactions Between Organisms II
Populations of prey and predators go in cycles:
- In a community containing prey and predators (as most of them do):
- The population of any species is usually limited by the amont of food available.
- If the population of prey increases, then so will the population of the predators.
- However, as the population of predators increase, the number of prey will decrease.
- Predator-prey cycles are always out of phase with eachother. This is because it takes a while for the population to respond to changes in the other population.
Parasitic and mutualistic relationships are other types of interactions:
Some organisms depend entirely on other species to survive. So where an organism lives and its abundance (population size) is often influences by the distribution and abundance of these species
PARASITES live off a host. They take what they need to survive, without giving anything back. This often harms the host - which makes it a win-lose situation
- Tapeworms absorb lots of nutrients from the host, causing them to suffer from malnutrition.
- Fleas are parasites. Dogs gain nothing from fleas.
Interacions Between Organisms III
MUTUALISM is a relationship where both organisms benefit - so it's a win-win relationship:
- 'Cleaner species', eg: oxpeckers live on the backs of buffalo. Not only do they eat pests on the buffalo like ticks, flies and maggots (providing the oxpecker a source of food). but they also alert the animals to any predators that are near, by hissing.
- Lots of plants are pollinated by insects, allowing them to reproduce. In return, the inspects get a sip of sugary, sweet nectar.
Adaptations help organisms to survive:
- Adaptions are the features that organisms have that make them better suited to their environment.
- Organisms that are adapted to their environment are better able to compete for resources.
- This means that they're more likely to survive, reproduce and pass on their adaptations to their offspring.
Organisms can be specialists or generalists:
- SPECIALISTS are organisms which are highly-adapted to survive in a specific habitat. For example giant pandas are adaoted to eat just bamboo.
- GENERALISTS are organisms that are adapted to survive in a range of different habitats. For example back rats are able to survive in forests, cities and in areas of farmland.
- In a habitat where the conditions are stable (eg: they're not changing), specialists will out-compete generalists as they're better adapted to the specific conditions.
- But if the conditions in the habitat change (eg: a species of prey becomes extinct), specialists will be out-competed by generalists. Specialists won't be adapted to new conditions, but generalists are adapted to a range of conditions so will be more likely to survive.
Some organisms have biochemical adaptations to extreme conditions:
- Some organisms can tolerate extreme conditions, eg: a very high or low pH or temperature.
- Organisms that are adapted to live in seriously extreme conditions (like super hot volcanic vents or at high pressure on the sea bed) are called extremophiles.
- Extremophile bacteria that live in very hot environments have enzymes that work best at a much higher optimum temperature than enzymes from other organisms.
- These enzymes are able to function normally at temperatures that would denature (destroy) enzymes from other organisms. For example, the bacteria Thermus thermophilus grows best in enviroments where the temperature is about 65*c.
- Organisms that live in very cold environments sometimes have special antifreeze proteins.
- These proteins interfere with the formation and growth of ice crystals in the cells, stopping the cells from being damaged by ice.
Adaptations to Cold Environments I
Some organisms have adapted to living in cold enviroments:
- Organisms that live in cold temperatures haave a whole host of adaptations to help them survive.
- Most adaptations to cold enviroments are based on reducing heat loss to the enviroment.
Anatomical adaptations can reduce heat loss:
Anatomical adaptations are features of an organism's anatomy (body structure) that help it to survive. Anatomical adaptations to the cold include:
- Having a thick coat or a layer of blubber to insulate the body and trap heat in.
- Having a large size and compact body shape to give a small surface area to volume ratio. This reduces heat loss as less body heat can be lost through the surface of the skin.
SURFACE AREA TO VOLUME RATIOS:
- A surface area to volume ratio is just a way of comparing how much surface area something has compared to its size.
Adaptations to Cold Environments II
- Small obkects have larger surface area to volume ratios than large objects.
- In cold environments, large organisms lose less heat to their surroundings than small organisms - because of their smaller surface area to volume ratio.
Having counter-current heat exchange systems:
- Animals like penguins have to stand on cold ice all day.
- Blood vessels going to and from the feet carry blood that flows in opposite directions.
- The vessels pass close to each other, allowing heat to transfer between them.
- Warm blood flowing in arteries to the feet heats cold blood returning to the heart in the veins.
- This means that the feet stay cold, but it stops cold blood from cooling down the rest of the body.
Some organisms also have behavioural adaptations to the cold:
- Many species migrate to warmer climates during the winter months to avoid having to cope with the cold conditions.
- Other species hibernate during the winter months. This saves energy as the animal doesn't have to find food or keep itself as warm as if it was active.
- Some species like penguins huddle together to keep warm.
Adaptations to Hot and Dry Environments
Some organisms have adapted to living in hot enviroments:
Keeping cool in hot environments is all about increasing heat loss and reducing heat gain.
Behavioural adaptations can increase heat loss and reduce heat gain:
- Animals that live in very hot climates often spend the day in the shade or underground to minimise the amound of heat their bodies gain from their surroundings.
- Animals can also reduce their heat gain by being active at night, when it is much cooler.
- Animals can increase heat loss by bathing in water. As the water evaporates it transfers heat from the skin to the surroundings, cooling the animal down.
Anatomical adaptations can also increase heat loss:
- Animals that are adapted to survive in hot environments are often small. This gives them a large surface area to volume ration which allows them to lose more body heat to their habitat
- Other adaptations, like having large ears, can also increase an animal's surface area to volume ratio and help them to 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 the surroundings.
- Some animals, eg: camels, store fat in one part of their body - this stops the rest of the body from being too well insulated and allows heat loss easier.
Evolution and Specification I
Only the fittest survive:
Charles Darwin came up with a theory about evolution. It's called the theory of natural selection:
- Darwin knew that organisms in a species show wide variation. He also knew that organisms have to compete for limited resources in an ecosystem.
- Darwin concluded that the organisms that are best adapted (the best fitted) would be more successful competitors and would be more likely to survive. This idea is called the 'survival of the fittest'.
- The sucessful organisms that survive are more likely to reproduce and pass on the adaptations that made them successful to their offsprings.
- The organisms that are less well adapted would be less likely to survive and reproduce, so they are less likely to pass on their characteristics to the next generations.
- Over time, successful adaptations become more common in the population and the species changes - it evolves.
New discoveries have helped to develop the theory of natrural selection:
- Darwin's theory wasn't perfect - he couldn't give a good explanation for why new characteristics appeared or exactly how individual organisms passed on beneficial adaptations to their offspring.
Evolution and Specification II
- That's because DNA wasn't discovered until 50 years after his theory was published.
- We now know that adaptations are controlled by genes. New adaptations arise because of mutations (changes in DNA). Successful adapatations are passed on to future generations in the genes that parents contribute to their offspring.
The development of a new species is called speciation:
- Over a long period of time, organisms may change so much because of natural selection that a completely new species is formed. This is called specification.
- Specification happens when populations of the same species change enough to become reproductively isolated - this means that they can't interbreed to produce fertile offspring.
Reproductive isolation can be caused by geographic isolation, here's why:
- A physical barrier divides a population of a species, eg: a river changes its course; the two new populations are unable to mix.
- Different mutations create different new features in the two groups of organisms.
- Natural selection works on new features so that, if they are of benefit, they spread through each of the populations.
Evolution and Specification III
- Since conditions on each sde of the barrier will be slightly different, the features that are beneficial will be different for each population.
- Eventually, individuals from the two populations will ahve such different features that they won't be able to breed together to produce fertile offspring. They'll have become reproductivelt isolated and the two groups will be different species.
Theories of Evolution I
Not everyone agreed with Darwin:
Darwin's theory of evolution by natural by natural selection was very controversial because:
- 1. The theory went against common religious beliefs about how life on Earth developed - it was the first plausible explanation for our own existence without the need for a 'creator' (God). this was very bad news for the religious authorities of the time, who ridiculed his ideas
- 2. Darwin couldnt explain why new, useful characteristics appeared or how they were inherited.
- 3. There wasn't enough evidence to convinve many scientists because not many other studies had been done into how organisms change overtime.
Lamarck had a conflict theory of evolution:
- Lamarck argued that if a characteristic was used a lot by an animal then it would become more developed. Lamarck reckoned that these acquired characteristics could be passed on to the animal's offspring. For example, if a rabbit did a lot of running and developed big leg muscles, Lamarck believed that the rabbit's offspring would also have big leg muscles.
Theories of Evolution II
Nowadays, most people accept Darwin's theory:
The theory of evolution by natural selection is now widely accepted. Here's reasons why:
- The theory has been debated and tested independently by a wide range of scientists, and no-one has managed to conclusively prove that the theory is wrong.
- The theory offers a plausible explanation for so many observations of plants and animals, eg: their physical characteristics and behavioural patterns.
The Carbon Cycle and Decomposition I
The carbon cycle shows how carbon is recycled:
Carbon is an important element in the materials that living things are made from. It's constantly being recycled in nature:
- The whole thing is 'powered' by photosynthesis.
- In photosynthesis plants convert the carbon from CO2, in the air into sugars. Plants can then incorporate this carbon into other carbohydrates, as well as fats and proteins.
- Eating passes the carbon compounds in the plant along to animals in a food chain or web.
- Both plant and animal respiration while the organisms are alive releases CO2 back into the air.
- Plants and animals eventually die and decy. They're then broken down by bacteria and fungi in the soil. These decomposers release CO2, back into the air by respiration as they break down the material.
- Over millions of years, material from dead plants and animals can also form fossil fuels like coal and oil. When these fossil fuels are burned CO2 is released back into the air.
The Carbon Cycle and Decomposition II
Decomposition is slower in waterlogged and acidic soils:
- Recycling of carbon and other nutrients takes longer in waterlogged soils than in well-drained soils.
- This is because bacteria and fungi that decompose organic material usually need oxygen to respire and produce energy. Waterlogged soils don't have much oxygen - so the decomposers have less energy and work more slowly.
- Nutrient recycling also takes longer in highly acidic soils than in neutral soils. This is because extremes of pH slows down the reproduction of decomposers or out right kill them.
Carbon is also recycled in the sea:
- There's another major recycling pathway for carbon in the sea.
- Millions of species of marine organisms make shells made of carbonates.
- When these organisms die the shells fall to the ocean floor and eventually form limestone rocks.
- The carbon in these rocks returns to the atmosphere as CO2, during volcanic eruptions or when the rocks are weathered down.
- The ocean can also absorb large amounts of CO2, acting as huge stores of carbon, called 'carbon sinks'.
The Nitrogen Cycle I
Nitrogen is recycled in the nitrogen cycle:
- The atmosphere contains 78% nitrogen gas, N2. This is very unreactive and so it can't be used directly by plants or animals.
- Nitrogen is needed for making proteins for growth, so living organisms have to get it somehow.
- Plants get their nitrogen from the soil, so nitrogen in the air has to be turned into nitrates before plants can use it. Nitrogen compounds are then passed along food chains and webs as animals eat plants (and eachother).
- Decomposers (bacteria and fungi in the soil) break down proteins in rotting plants and animals, and urea in animal waste, into ammonia. This returns the nitrogen compound to the soil so the nitrogen in these organisms is recycled.
Nitrogen fixation is the process of turning N2 from the air into nitrogen compounds in the soil which plants can use. There are two ways that this happens:
- LIGHTING - there's so much energy in a bolt of lightning that it's enough
- NITROGEN-FIXING BACTERIA - in roots and soil.
The Nitrogen Cycle II
There are four different types of bacteria involved in the nitrogen cycle:
- DECOMPOSERS - decompose proteins and urea and turn them back into ammonia.
- NITRIFYING BACTERIA - turn ammonia in decaying matter into nitrates
- NITROGEN-FIXING BACTERIA - turn atmospheric N2 into nitrogen compounds that plants can use.
- DENITRIFYING BACTERIA - turn nitrates back into N2 gas. This is of no benefit to living organisms.
Some nitrogen-fixing bacteria live in the soil. Others live in nodules on the roots of legume plants (eg: peas and beans). This is why legume plants are good at putting nitrogen back into the soil. The plants have a mutualistic relationship with the bacteria - the bacteria get food (sugars) from the plant, and the plant gets nitrogen compounds from the bacteria to make proteins. So the relationship benefits both of them.
Human Impact on the Environments I
Human population is increasing:
- The world's human population is rising exponentially - which means increasing very quickly.
- Populations increase when the birth rate (the number of people who are born each year) is higher than the death rate (the number of people who die each year).
- The rapidly increasing population is putting pressure on the environment - more resources are being used up and more pollution's being produced.
- The higher standard of living amongst more developed countries demands even more resources, and although these developed countries have only a small proportion of the world's population, they cause a large proportion of the pollution.
Increasing amounts of pollution are causing...
1. GLOBAL WARMING:
- Fossil fuels are coal, oil and natural gas.
- When they're burned, they release lots of carbon dioxide, which is a greenhouse gas. Greenhouse gases trap heat in the atmosphere which causes global temperatures to rise. This is global warming.
Human Impact on the Environments II
- Scientists have predicted that, if global temperature continues to go up, sea level will rise, weather systems will become less predictable and agricultural output will fall.
- Lots of people, companies and countries are measuring the amount of greenhouse gases they're giving off, so they can reduce their emissions. The amount of greenhouse gases given off in a certain period of time (eg: by a person) is called their carbon footprint.
2. ACID RAIN:
- When fossil fuels and waste materials are burned they release a gas called sulfur dioxide.
- Sulfur dioxide reacts with water in the atmosphere to form sulfuric acid which falls as acid rain.
- Acid rain damages soils, and can kill trees.
- Acid rain can cause lakes to become more acidic. This has a severe effect on the lake's ecosystem. Many organisms are sensitive to changes in pH and can't survive in more acidic conditions. Many plants and animals die.
- Acid rain damages limestone, ruining buildings and stone statues.
Human Impact on the Environments III
3. OZONE DEPLETION
- CFCs (chlorofluorocarbons) used to be used in aerosoles, fridges, air-conditioning units and polystyrene foam.
- They break down ozone in the upper atmosphere.
- This allows more harmful UB rays to reach the Earth's surface.
- Being exposed to more UV rays will increase the risk of skin cancer (although this can be reduced with suncream). Australia has high levels of skin cancer because it is under an ozone layer.
- The sea ecosystem because plankton are at the bottom of the food chain. Scientists predict that the sea ecosystem because plankton are at the bottom of the food chain. Scientists predict that fish levels will drop (meaning, among other things, less food for us to eat)
Human Impact on the Environments IV
Indictator species can be used to show pollution:
By looking for indicator species, you can tell if an area is polluted or not.
- Some species can only survive in unpolluted conditions, so if you find lots of them, you know it's a clean area. Lichens are used to monitor air quality - they're damaged by pollution. The cleaner the air, the greater the diversity of linchens that survive. Mayfly larvae are used to monitor water quality - they can't survive in polluted water. The cleaner the water, the more mayfly larvae survive.
- Other spcies have adapted to live in polluted conditions - so if you see a lot of them you know there's problem. Water lice, rat-tailed maggots and sludgeworms all indicate polluted water. But out of these, rat-tailed maggots and sludgeworms indicate a very high level of pollutions.
Pollution level can be measured:
There are a couple of ways using indicator species to measure pollution:
Human Impact on the Environments V
- You could do a simple survey to see if a species is present or absent from an area. This is a quick way of telling whether an area is polluted or not, but it's no good for telling how polluted an area is.
- Counting the number of times an indicator species occurs in an area will give you a numerical value, allowing measurements from different areas to be compared so you can see how polluted an area is.
You can also measure population directly, for example:
- Sensitive instruments can measure the concentration of chemical pollutants, eg: carbon dioxide or sulfur dioxide, in samples of air or water.
- Satellite data can also be used to indicate pollutant level, eg: satellites can show where the ozone layer is thin or absent, which is linked to the CFC levels.
Both ways of looking at pollution level have their weaknesses:
LIVING METHODS (INDICATOR SPECIES)
- Advantage - using living methods is a relatively quick, cheap and easy way of saying whether an area is polluted or not. No expensive equipment or highly trained workers needed.
Human Impact on the Environments VI
- Disadvantage - factors other than pollution (eg: temperature) can influence the survival of indicator species so living methods aren't always reliable.
- Advantage - Directly measuring the pollutants gives reliable, numerical data that's easy to compare between different sites.
- Advantage - The exact pollutants can be identified too.
- Disadvantage - Non-living methods often require more expensive equipment and trained workers than methods that use indicator species.
Endangered Species I
Many factors can cause a species to become extinct:
- Endangered species like tigers have very low numbers left in the wild. They're in danger of becoming extinct, where there's none of them at all - like the dodo and woolly mammoth.
Species are at risk of extinction if the following factors fall below a critical level:
- THE NUMBER OF HABITATS - It's hard for organisms to find resources like food and shelter if there aren't enough suitable habitats to support them.
- THE NUMBER OF INDIVIDUALS - if there are only a few individual members of a species left, it'll be hard to find mates. It also means there won't be much genetic variation in the population.
- GENETIC VARIATION - This is the number of different alleles (forms of a gene) in a population. If genetic variation is low, then a species is less likely to be able to adapt to the changes in environment or survive the appearance of a new disease.
You need to be able to evaluatie conservation programmes:
Conservation programmes are esigned to help save endangered plants and animals. They involve things like protecting habitats, creating artificial environments and captive breeding.
Endangered Species II
You can EVALUATE how successful a conservation programme is likely to be by looking at:
- GENETIC VARIATION - the species being conserved should have enough genetic variation to survive the appearance of new diseases and to cope with environmental change.
- VIABILITY OF POPULATIONS - populations should be able to reproduce - so they must contain both males and females of reproductive age. They should also be large enough to prevent related individuals having to breed together - this is called inbreeding and it reduces genetic variation.
- AVAILABLE HABITATS - there should be plenty of suitable havitats to live in. The right type of habitat is especially important if the organisms being conserved are specialists.
- INTERACTION BETWEEN SPECIES - it's important that species interact with each other as they would in their natural environment, eg: predator species should be allowed to hunt prey.
Conservation programmes benefit wildlife and humans:
Conservation programmes do more than just benefit endangered species - they often help humans too:
- PROTECTING THE HUMAN FOOD SUPPLY - overfishing has greatly reduced fish stocks in the world's oceans. Conservation programmes can ensure future generations will have fish to eat.
Endangered Species III
- ENSURING MINIMAL DAMAGE TO FOOD CHAINS - if one species becomes extinct it will affect all the organisms that feed on and are eaten by that species, so the whole food chain is affected. This means conserving one species may help others to survive.
- PROVIDING FUTURE MEDICINES - many of the medicines we use today come from plants. Undiscovered plant species may contain new medicinal chemicals. If these plants are allowed to become extinct, perhaps through rainforest destruction, we could miss out on valuable medicines.
- CULTURAL ASPECTS - individual species may be important in a nation's on an area's cultural heritage, eg the bald eagle is being conserved in the USA as it is regarded as a national symbol.
Sustainable Development I
Development has to be sustainable:
As the human population gets bigger...
- We need to produce more food - so we'll need more land for farming.
- We use up more energy. At the moment the vast majority of energy comes from burning fossil fuels. But these are rapidly running out = we need to find an alternative energy source.
- We're producing more waste - it all needs to be put somewhere and a lot of it's polluting Earth.
- SUSTAINABLE DEVELOPMENT means providing for the needs of today's increasing population without harming the environment.
- Sustainable developement needs to be carefully planned and it needs to be carried out all over the Earth. This means there needs to be cooperation locally, nationally and internationally.
- Fishing quotas have been introduced to prevent some types of fish, such as cod, from becoming extinct in certain areas. This means they'll still be around in years to come.
- To make the production of wood and paper sustainable there are laws of insisting that logging companies plant new trees to replace those they've felled.
- Education is important, if people are aware of the problems - they will probably help.
Sustainable Development II
CASE STUDY: Whales - Some species are endangered:
- Whales have commercial value (they can be used to make money) when they're alive and dead.
- They're a tourist attraction - people go to some areas especially to see the whales.
- Whale meat and oil can be used, and cosmetics can be made from a waxy substance in their intestines. However, this has led to some species of whale becoming endangered.
- The International Whaling Commision (IWC) has struggled to get nations to agree to restrict whaling. In 1982, the member nations declared a stop to whaling, the only exception being Norway, which still catches whales. Taking a small number of whales ('culling') for scientific research is allowed and is carried out by Japan, Iceland and the Faroe Islands.
- But it's hard to check that countries are sticking to the agreement, and even when anyone is caught, the ICW doesn't have the authority to enforce any kind of punishment so nothing happens
Some whales are kept in captivity - there are different views about this:
- Whales don't have much space in captivity and they are sometimes used for entertaining people. Some people think it's wrong that the whales lose their freedom and that they would be much happier in the wild, but captive whales do increase awareness of the animals and their problems
Sustainable Development III
- Captive breeding programmes allow whales to be bred in numbers and released back into the wild.
- Research on captive whales can help us understand their needs better to help conservation. There is still a lot we don't fully understand about whales, eg: whale communication, their migration patterns and how they survive in very deep water.