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.

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 Rainforest Ecosystem (Amazon Project Part 2)

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The Amazon is the richest ecosystem on the planet, as 50% of all plant and animal species are found there. Over 100 million years old, it is 30 times the size of Great Britain and is the largest basin on Earth.

The Amazon is partly 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 Emergents. 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 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.

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The trees also play a major part in the nutrients cycle. 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.

The Amazon is also the wettest and the hottest place on Earth. The water cycle help keeps the rainforest alive. 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 back into the river.

Clouds over Forests in the Amazon

Now this is not happening. Deforestation breaks the cycles. The rain penetrates the ground directly, washing away the nutrients in the soil. 20% of the Amazon rainforest land in 1970 has now been turned into wasteland. Will the rainforest recover? Deforestation needs to stop now.

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.

The Warehouse

The abandoned warehouse has not been used in years. The small city windows are all boarded up. As you stare through the open door, the shadows seem to dnace menacingly, creeping ever closer towards you. As you step cautiously inside, you are hit with the smell of rotting flesh. The sound of dripping draws you down one dull, damp corridor after another. The old rusty doors on either side of you refuse to open. They feel cold and slimy. You come across a grand hall, stacked to the ceiling with cardboard boxes. Bubble wrap and other packaging is scattered around carelessly. Someone was looking for something. As you walk towards some steep steps leading to the next floor, you feel as though you are being watched. A cold breeze blows towards you, willingly you to turn back. You can hear footsteps around the corner. As you walk towards the noise, you see what seems to be red paint scattered on the floor. Turning the corner into an office, you see papers in disorganised heaps on the floor. The light bulb above you begins to crackle and flicker in anticiption. You walk down a passageway into a small room. A beam of light, seemingly from nowhere, shines onto an old, dusty book. As you open it intrigued, you discover what it is; a diary of a young girl. The last page is not finished, it end in a long line going across the page and  you notice there are scratch marks on a neaby box. You can smell smoke, as if someone has lit a fire next to you. In the adjoinging room, there is a small fireplace with a raging fire burning inside. Heat and light leads you towards the discovery of shelf upon shelf of plants in black, plastic pots, as if someone had turned the wall had been turned into an indoor greenhouse. Perplexed, you move on. The last room upstairs is completely empty except for a single bloodstained cloth. You go back down to the ground floor by a creaky lift. Just as you are about to leave, you hear the sound of smashing glass. A hole in the wall takes you to an unlit room you missed before, with a sturdy iron door. In the corner you see what seems to be a life-size doll, but as you come closer you realise it is a young girl, about 13, lying motionless on the floor. The pieces of the puzzle finally piece themselves together in your mind. You run for the door but it slowly closes in front of you. You realise where you are, and why no one dares to come here. It is the place for a murderer and his victims.