Cloning In Plants And Animals

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Clones are abundant in nature – when a zygote splits in two identical twins are formed, when bacteria divideasexually by binary fission the resulting bacteria are clones of the original bacterium, when plants reproduce asexually by producing runners the resulting plants are clones and when a singles cell divides during mitosis the two daughter cells are clones. These clones produced by asecual reproduction are advantageous as the process is quick, can be carried out when sexual reproduction cannot and all of the offspring have the genetic information to allow them to survive in their environment. However, asexual reprodcution generates no genetic variation, unless a mutation occurs, and so all of the offspring are equally suscebtible to envorinomental changes such as the introduction of a new disease-causing pathogen.

There are two main types of cloning – reproductive and non-reproductive. Reproductive cloning is the production of offspring which are genetically identical to either their mother, if created by nuclear transfer, or the other offspring, if created by splitting embryos. Non-reproductive cloning is the use of stem cells in order to generate replacement cells, tissues or organs which may be used to treat particular diseases or conditions in humans.

Splitting embryos is the process of seperating out cells from a developing embryo and so producing separate, genetically identical organisms:

splitting embryos

Nuclear transfer is when the nucleus of a differentiated adult cell is placed in an enucleated egg cell:

nuclear transfer

Advantages of artficially cloning aniamls:

  • High value animals, such as cows with a high milk yield, can be cloned in large numbers.
  • Rare animals can be cloned in order to preserve the species.
  • Genetically modified animals, such as goats which produce spider silk in their milk, can be quickly produced.

Disadvantages of artifically cloning animals:

  • As with asexual reproduction, the genetic unformity of cloning means that all of the offspring will be susceptible to environmental changes.
  • Animal welfare is not always taken into account, for example chickens with a high meat yield, yet are unable to walk, have been produced.
  • It is not yet known if animals cloned using nuclear material from adult cells will develop any long term health problems.

An example of natural vegetative propogation is the English Elm tree. After damage to the parent plant, such as disease or burning, root suckers (basal sprouts) begin to grow from the meristem tissue in the trunk close to the ground, as this is where the lest damage is likely to have occured. This response to stress or trunk death helps the elm to spread, for example, when an elm is felled during copicing, the root suckers grow into a circle of new elms, called a clonal patch, around the old trunk. These new elms produce their own root suckers, and so the clonal patch continues to expand where resources permit it. However, this adaptation can also be disadvantageous, in particular when it is in response to Dutch elm disease. The roots of an elm infected with dutch elm disease will produce many root suckers, but as these suckers are clones of the original plant they have no resistance to the fungal attack and so as they continue to grow they also begin to show symptoms of the disease. Many plants we take for granted also use vegetative propogation as a survival mechanism – potatoes form tubers which are underground stems swollen with nutrients from which new plants grow, onions and daffodils form bulbs which are condensed shoots containing nutrients and from which new bulbs can fom and strawberries have specialised stems, called runners (see below), which grow along the ground, forming new roots and shoots at the tips. These adaptations all mean the plant can reproduce even if it becomes isolated and there is no reliance on wind, insects or other pollinating agents, but the tubers and bulbs are also a disadvantage as they are an attractive foood source for certain animal including us humans.

natural_vegetative_propogation

Plants can also be propogated aritifically. Traditionally there were two methods of doing this; taking cuttings and grafting:

Taking cuttings is where a stem is cut between nodes and its lower leaves are removed. The cut end is then treated with plant hormones to encourage root growth  before planting. The cuttingss are clones of the parent plant. Commercially this techniques is used to quickly produce large numbers of plants such as geraniums.

cuttings

Grafting is where a shoot section of a woody plant, such as a rosebush or fruit tree, is joined to a rootstock (a root and stem already growing). The graft then grows and is a clone of the original plant, but the rootstock is genetically different.

grafting

Although these methods are useful they cannot easily produce high numbers of plants and some plants struggle to reproduce successfully in these ways. The more mordern method of artificial vegetative propogation is micropropogation by callus tissue culture. This method can quickly produce very large stocks of a plant from a small amount of plant tissue, and it has an added advantage that the stock is disease free. Many household plant, such as orchids, are produced using the following method:

  1. A small piece of tissue (an explant) is taken from the shoot tip of a plant.
  2. The explant is placed on a nutrient growth medium and cells in the tissue divide to form a callus (a mass of undifferentiated cells).
  3. Single callus cells are seperated from the mass and placed on a growing medium with plant hormones that encourage shoot growth.
  4. These growing shoots are then transferred to another medium with hormones encouraging root growth.
  5. Growing plants are then transferred to a greenhouse to acclimatise and grow further, before being planted outside.

micropropogation

Plant cloning in agriculture has both advantages and disadvantages. Lots of genetically identical plants can be produced from one plant – you know what the plants will be like and the process is faster than selective breeding. Also, costs are reduced as the crop is all ready at the same time and plants can be produced at any time of the year instead of having to wait until their natural growing season. However, the process is arguably more labour intensive as it’s harder to replant small plants than sow seed. Most importantly, environmental change such as the arrival of a new disease could damage the whole crop as their identical genetics means that they would all be equally susceptible.

Tourism!

With the January exams looming I thought I’d share my revision notes for the geography unit on tourism 🙂

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Consequences of rainforest exploitation (Amazon project part 5)

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Due to these activities, everything is affected. The natives that live in the forest are fighting for survival. Logging companies are cutting down dense areas of forest and only leaving small pockets of not very dense forest. This means they cannot hunt for food, and many of the tropical plants they use to store food eat and use as medicines are all being cut down. Cutting down trees affect their water supply, instead of being pure and fresh mineral water it becomes muddy and useless. This is because there are no trees so rain hits the ground directly. This pulls mud from the top soil into the rivers. This means the natives have no clean water to drink or to wash with. The fish struggle to live in that dirty water and many species could be wiped out. The natives would have nothing to eat. The natives have to heavily rely on getting supplies from the outside world, but they do not have enough money to get what they need.  They have to become farmers, but their crops do not sell at a high enough price. These markets where they buy and sell supplies could be miles away and the only way to get to them is by a long trek by foot that could last for days, or they would have to row all the way and risk the dangers of the water such as wild animals. They cannot move any closer to the markets as the land is already being used for farming, mining or logging. We are killing of the indigenous people of the forest. 

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Not only are the natives affected, plants and animals are affected too. By cutting down the trees, we are killing off the animals of the forest. The tall trees in the canopy provide food and shelter for a wide range of species including monkeys and lizards. Without this home, they cannot survive. Other groups often reject any animals that do survive and escape to another part of the forest. The animals cannot drink any fresh water because the rainwater hits the soil directly and washes mud into the river. This causes the animals to catch diseases. This could wipe out whole species in no time. There are still thousands of species that could help us learn more about the world, but scientists are not getting the chance to find these animals. After the trees are cut down, the nutrients and water cycles are broken. This means in a few years the land will become wasteland and practically useless. There are plants out there, which we have not discovered, and yet they are being cut down and the whole species is being made extinct. These plants could hold the keys to curing diseases such as aids and cancer, but scientists are not being given the chance to find these plants. These plants could save hundreds or even thousands of people each year. This means one day, if a loved one becomes seriously ill, we will not have a cure that will definitely cure them, and we are all putting ourselves in danger. When logging companies leave some trees because their value is not worth the effort or time to cut down when there are lots of more valuable trees, those trees may die as well because they get damaged whenever another tree is cut down. More animals will be affected.  Dragging the trees down the river by using a boat to tow them affects the wildlife in the rivers because animals may get caught in-between them and die.

There is a serious global threat partly due to with the way we live and partly due to the cutting down of the rainforests worldwide. As we all know, plants take in carbon dioxide in the atmosphere and use it to keep them alive and in return, they give out oxygen-essential for our survival.  However, we are cutting down all of the trees and burning an awful lot of them. This produces a lot more carbon dioxide as well as other harmful gasses. As there are even less trees to absorb this carbon dioxide, a lot more escapes into our atmosphere and rises up to form a protective layer around the Earth, as explained in the diagram below.

earth

When the sun’s rays hit the Earth, as usual, most of that energy is absorbed by the Earth to heat it up. The problem is, normally, some of those rays are not needed and are reflected back towards the sun. Now, because of excessive amounts of Carbon dioxide, these rays are reflected from the earth to the atmosphere, but the rays cannot escape through carbon dioxide so they are reflected back to the Earth and so on.  This means the Earth is heating up by 1 degree per year. This does not sound like much, but the way we are going, it is going to increase. This sudden rise in temperature means the polar ice caps are melting at an extraordinary rate. Sea levels are set to rise by meters, and if the Thames barrier and other defences that are going to be put in cannot hold the water back, Most of England could be under water and look a bit like the picture below- part of the sea.

 sea

Animals cannot adapt in time and the natives have nowhere to go so whole species is the polar ice caps are becoming extinct.  Even the rainforests might flood with salty seawater, and no plants and very few animals would be able to survive. The whole rainforest would be destroyed and there would not be enough land for the whole population of humans to live.

Exploiting the Rainforest (Amazon project part 4)

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Humans have been exploiting the forest for thousands of years. Today, we still use a technique used in the early 20th century to make tyres. One man may look after 30 hectares of land, but only find 60 rubber trees. The rubber taper then scrapes some diagonal lines through the bark. A natural resin called latex; which lies just underneath the bark, comes out and is collected. They then turn this into rubber. A rubber tree can be harvested many times, and does little or no damage to the environment.

 

Now, most ways of exploiting the forest starts with a chainsaw, and cutting down hundreds of trees. Logging companies specialize in this field. They tend to cut down the most valuable trees like Mahogany. Mahogany is in great demand, especially in the UK. Mahogany is worth £500 per cubic meter, or around £10,000 per tree. These trees are rare as the logging companies can only find one to two adult trees per hectare.  To get to these precious trees, the companies must build roads, cutting down lots of trees. Then when they find a tree they want, they cut it down, pulling down and damaging others trees in the process. Next, they drag it out to the road and load it onto a truck. Pulling down one tree damages at least 28 others in the process. They then go back in to get about 20 less valuable trees for timber, doing the same amount of damage each time. In one area there may be to logging companies, where they have to cut down 30 trees a day ach, totalling 300 trees per week or a massive 15,000 per year. Only some legal companies replace less than a third of what they took, but the illegal companies do not care. The Lorries taking the trees are relentless. Whether they are taken away by river or road, the trees all end up in the same place, the sawmill. There is said to be over 4,000 sawmills in Amazonia. In the sawmills they cut extremely thin slices of the less valuable timer, and then stick them together to make ply wood. The Amazonian hard wood is in great demand. Before, we use to exploit the tropical forests of Asia, but that supply is almost completely gone. So more and more companies have come to Amazonia, causing vast areas of damaged land.

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Another way of exploiting the forest is mining. First, they clear a huge area of forest, and then dig deep below the surface. The rocks underneath the Amazonian soil are rich in minerals such as gold, copper, iron, lead and many more. One of the big mines is translated as being called Great future, but others tell a different story. This mine now produces 3.000 tones of these precious minerals a year, compared to the 15,000 tones at its peak. They use high-pressure hoses to wash the unwanted soil away, making large ponds. Where there is unweathered rock, they employ hundreds of local people to use a pick and shovel to mine the ore out.  These people are lucky to get £10 a day. To make the tin that we use for cans, the ore is heated and ground several times. They then wash it in water, and the tin sinks to the bottom, where as all the other minerals wash away. The tin costs $6,000 a ton and is sent to factories to be made into objects like cans. There are many mines like this across the Amazon, and now places where the earth contains oil, gas and uranium are being discovered.

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Although logging and mining area both big causes of deforestation, the biggest cause so far is cattle ranching. When the government gave away free land, many took advantage, most of whom made cattle ranches. They cleared a huge area of land, so big; they have to use mobile phones to communicate. One particular ranch has 2,000 cattle in 3,000 hectares of land. Though compared to the Brazilian government standards, this is only a medium sized ranch. The neighbouring ranch has 15,000 hectares of land and s classed as a large ranch. The owners keep a specially bred type of cattle called zeboo cattle. To improve their herd, they use modern techniques and chemicals such as Artificial Insemination, where they make the females pregnant. Despite all this, there is o0nly enough beef for their own population.  After about 3 years, the soil becomes so acidic, the only thing that will grow is grass, grass so poor that even the cows don not like to eat it. As fertilizer is not available in large quantities n the area, the fields are just enlarged when the soil becomes infertile. If this continues, ranches will own a great deal of the land in Amazonia, but in Amazonia, clearing land is a way of claiming it as yours.

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The last method of exploiting the forest is farming. 10,000 small farmers picked up the offer of free land, so roads were built through the forest. Over 1,000,000 people came to the Amazon, but nothing happened. They were promised a new start in a new place, with money and fertilizer, but the Brazilian government did not live up to its promises. Many people made them selves a 50 hectare plot, but the Amazonian soil did not live up to its promises either. So most people left the plot, and cleared more land somewhere else. For the few that stayed, life is hard. They grow coffee, coco, corn rice and fruit, but only for low prices. The soil is very infertile so the crops they can grow can not live up to their potential. They get by with what they can, and even though they continually beg the companies and the government for more money, the answer is always no.

Through all this, deforestation is the key issue; it affects the climate, the environment and the indigenous people within the forest. It is said hat the Amazon rainforest will be almost completely gone in 40 years time, but the Brazilian government disagree, saying it will not be gone for at least another 300 years time. Whatever the correct figure, can we really afford to lose one of nature’s best creation? The clock is ticking and it only so long before the rainforest is gone, unless we all do something about it.

Living in the Amazon (Amazon project part 3)

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There are hundreds of tribes in the Amazon. One of them is the Jackoona tribe. They were contacted during the 16th century, and since then, their traditions have changed, although some still many remain.  

Most of the time, their main priority is food. They only have a basic diet. On land,  they grow crops using a technique called shifting cultivation. This is where they clear an area of forest, maybe a few hectares. Then they plant and grow crops around tree stumps. They keep the tree stumps because the roots will hold on to the soil making sure the nutrients doesn’t wash away when it rains because there are no trees. When the land becomes infertile, they move and clear another few hectares while the first few hectares grow back into dense forest. The cycle carries on like this, and about 30 years after they cleared the first hectares of land, those first hectares of land is now fertile and ready to clear again. In the land, they grow mainly root vegetables, pineapples, bananas and beans.

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Another source of food is fishing. Most of the fish in the Amazon are freshwater fish. This is their main source of protein. One way they fish is by hollowing out a tree to make a canoe, then canoe down the river and use a net to collect fish, and then stab them so they die or shooting fish with an arrow with deadly accuracy. Another way is to build a dam in a stream. Then, get some poison roots from a tree and slit them. Meanwhile, some women will weave some baskets out of grass. They then wave the roots in the stream. This stuns the fish so they have to come up for air. They then catch them with the baskets.

Sometimes this food is not enough. If they have any left over food they do not need they take it to the market and trade it for modern clothes and other things like guns, but they mainly rely on the surrounding environment. If one man has any bullets to shoot, he will try to kill a monkey or bird. However, the bullets are expensive and successful shots are rare.

The Jackoona build there homes on stilts to keep them safe, dry and cool. These indigenous people use everything around them without destroying their environment. They all help each other, even the children.

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Now, businesses are trying to take over. Already they have forced or killed over half a million indigenous people like the Jackoona. The Jackoona children are now being taught Portuguese, maths and other useful skills just so they can survive in the growing world that is leaving them behind.

Another tribe is the Kabocka tribe. These people are more damaging to the environment and have some very different traditions. One of these traditions is when a child has gone through puberty; they are given an alcoholic drink during a special ceremony to make them unaware of what is going on. Next, they kneel down and everyone else in the village pulls out all of the hair on there head as a punishment for their sins as a child.

Their way of cultivation plays a major part in deforestation. Unlike the Jackoona tribe, when the soil becomes infertile, they just make that cleared area of land bigger. Therefore, instead of them using it as land to grow crops, they use it as pasture for the few cattle they keep for food, but of course the pasture is rubbish as the soil is infertile and hardly anything will grow there. This technique is called slash and burn cultivation. As their area of cleared and is so huge, children as young as six have their own plot to take care of.

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Another way the Kabocka get there food is by growing a poisonous plant called manioc. They have somehow managed to work out how to extract he poison. First they peel it and but in a special weaved basket made from palm leaves to squeeze out the poisonous juice. Next, they bake it in a massive pan to make a flour like substance, which is their main source of carbohydrate.

A different Kabocka tribe live on one of the many flood plains In the Amazon. During the wet season, they cut down long grass and feed the cattle and other animals they have. They fish, but it is harder to catch lots, as there is a bigger and deeper area of water. When the water gets shallower, the use fishing as a source of income, as well as saving some as a food supply for the winter months. During the dry season, they can grow many crops as the flood brings silt onto the flood plain, putting lots of nutrients back into the soil. They often find levees (natural mounds of silt) on the riverbanks.

The indigenous people having to change. As you move further east across the Amazon, the more these once independent tribes are becoming more involved with the outside world, like becoming more involved in trade. Living in the Amazon is an ongoing struggle between them and the growing pressure from the outside world. There are still uncontacted tribes out there but how long is it before the indigenous people are forced out of the way?

The Tropical Rainforest (Amazon Project Part 1)

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The Tropical rainforest is a forest found near the equator. The temperature only varies by a few degrees all year. It looks green all year round even though many of the trees are deciduous, because there is a constant temperature there are no seasons so the trees lose their leaves at different times of year. The rainforests hold more of the world’s species of plants and animals than any other biome. The Amazon has around 50% of the world’s species of plants and animals.

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The rainforest is mainly made up of well-designed and adapted trees. These millions of trees grow in four main layers. The top layer of trees is made up of very tall trees reaching heights of over 50 meters called Emergent. They have specially designed buttress roots so they do not fall over. The next layer is called the canopy, with trees growing to around 30 meters. This is where most of the animals live; flowers grow and the layer that gets the most light. The next layer is called the under canopy or under storey with trees growing to around 10meters. Here it is quite dark. The last layer is the shrub layer. Here it is very quiet and plants may only get sunlight for a few minutes of the day, so they have very dark green leaves and turn to face the sun. Some plants have adapted to grow on the taller trees and use their energy to survive. The animals have adapted to have bright and bold colours, being able to make a loud noise and eat diets that consist mainly of fruit as well as living in the canopy where there is more food and light. The nutrients cycle helps to keep the rainforest alive. Most of the trees are deciduous, but they all lose there leaves at different times of the year, so the forest floor is always covered in leaves all year round. Decomposers then eat these leaves. They then excrete and put nutrients back into the soil. The trees then suck up the nutrients so they can grow. Sometimes over plants will grow on the trees, and suck nutrients from their host tree. The tree then loses it leaves and the cycle starts again.

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The Tropical Rainforest is found mainly between the Tropic of Capricorn to the south and the Tropic of Cancer to the north. It is found here, as there is a hotter climate because there is more direct sunlight hitting the earth, as it is not as round as the top of the Earth, so the sun has a smaller area of land to heat. The main areas of tropical rainforest are shown on this map. The two red lines show the topics of cancer and Capricorn

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It rains a lot in the Rainforest because it is very hot all day. This is part of the water cycle. As the sun heats the ground, it heats the air above it. The warm air then rises, cools, and condenses, causing convectional rainfall.  Some of the rain is evaporated off the leaves or held as moisture in the leaves. Some water runs off the leaves and is absorbed into the soil. The rest runs off into the river. Only about 20% of the rain makes it backinto the river. As you can see by this climate graph, the amount of rain does vary a lot throughout the year; there is always plenty of water. The temperature does not vary much at all.

MEDC Urban Development Problems

Case Study: Congestion and Traffic Management in Chelmsford

Causes:

  • There is fairly poor public transport so many prefer to use their own means of transport instead.
  • Chelmsford is a thoroughfare to get to other places such as Colchester as the A12 and A414 run through it, meaning there are more cars on the road.
  • There is an increase in car ownership as cars are becoming cheaper to buy second-hand.
  • Chelmsford is built on old road systems that only allow one lane each way with no room to expand as there are too many buildings, and so the roads cannot cope today’s volume of traffic.
  • Chelmsford is the county town of Essex and is a big town so many people are moving here in the hope of employment.
  • People are travelling further to reach work as they have car access instead of taking local jobs to them in walking/cycling distance so there are lots more cars.

Effects:

  • People may become consistently late to work as they struggle to get through the town to their work amidst all the traffic
  • It increases the amount of road-rage experienced by frustrated drivers stuck in long queues.  
  • There may be an increase in the amount of collisions/rashes as there are more cars on the road. Also, people who become fed up with being stuck in traffic jams may drive more dangerously such as performing
  • All the traffic on the roads means it becomes very difficult for local businesses to transport their goods or have other companies deliver goods to them.
  • There becomes tension between car owners and environmentalists as car owners want to drive but environmentalists are angered by this as it is damaging the environment. 
  • There also becomes tension between locals and commuters as the commuters are causing a great deal of the congestion, and the locals cannot get around their own town easily or have to wait for long periods of time to park their car in their driveway.
  • The total amount of money spent on petrol increases as more is used sitting in traffic, and local companies can exploit the high demand by increasing prices.
  • The fumes from all the cars cause vast amounts of air pollution. For example, these gases can cause illnesses and potentially cancer, especially in high risk groups such as the elderly or the asthmatic. Also a lot of carbon dioxide is produced, which is one of the gases contributing to global warming.

Solutions:

  • Some roads have become pedestrian orientated to keep cars away from high risk area e.g. in the town centre the high street isn’t used for any vehicles, and also they cannot make any pollution here.
  • Hybrid cars could be developed and promoted. These would cut down on the carbon emissions as well as other detrimental gases.   
  • Smaller cars and car sharing could be promotes which would cut down on emissions and the amount of congestion on the roads.
  • Park and ride/park and cycle schemes could be promoted cutting down on traffic and pollution in the main area of the town.
  • Congestion charges could be enforced around the town centre to discourage people from driving there, encouraging them to find alternative means of transport.
  • More bus lanes could be built to improve the flow of public transport. Or cycle lanes to encourage cycling and keep cyclists out of pedestrian’s and cars way.
  • More tax could be put on petrol and diesel to discourage drivers from using their cars all the time.
  • Buses could become free or a lot cheaper to encourage more people to use them on a regular basis.
  • Parking costs in the town could be increased to encourage people to use public transport, walk or cycle to wherever they need to go if possible.
  • Alternative means of transport need to be explained and promoted such as walking to school (walking bus)
  • Cycling should be promoted as it is very environmentally friendly and also has health benefits.
  • Traffic calming measures such as speed bumps, speed cameras and 20mph speed limits should be introduced to reduce accidents by cars.