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Edexcel Categories Archives: Topic 4: Biodiversity and Natural Resources

Measuring biodiversity

Measuring biodiversity

Specie richness is the simplest way to measure biodiversity, this involves counting all the species present in a given habitat.

Specie evenness is when you use specie richness but you take into account the population size of each of the species.

Usually in an ecosystem there is a dominant organism. This is the most common specie in the habitat. In English woods it is often the Oak tree.

 

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Conservation of Biodiversity

Conservation of Biodiversity

Zoos and seed banks help to conserve endangered species. The extinction of a specie or the loss of genetic diversity can cause a reduction in global biodiversity. Some species such as the Dodo have already became extinct, and many and endangered.

Seedbanks is a store of lots of seeds from different plant species. This is to help conserve the biodiversity by storing the seeds of endangered plants. So if plants have became extinct in the wild, then they can be re-grown via the seed. The also keep a range of the same seed but with a different genes, so that have a good genetic biodiversity. It involves keeping the seeds in a dry, cool condition, so the seeds can be stored for a long time. Testing the viability of the seeds. Seeds are planted, grown and new seeds are harvested to keep stocks up. An example of this is the millennium seed bank (MSB)

Zoos have captive breeding programs to help endangered species. These are in controlled environments.  Species which are endangered or which are already extinct in the wild  can be bred together in zoos to help increase their numbers. Such as Pandas. But there are some problems with it,  animals can have problems breeding outside their natural habitats, and some people think it is cruel.

These animals or plants can be reintroduced into the wild, this is to bring them back from the brink of extinction, and to boost their numbers. An example is the Californian condor, which only 22 were left in the wild, but this number is now around 300 due to captive breeding.

But reintroducing them to the wild can bring new diseases to the habitat, which can harm other organisms there. The animals may also not behave naturally, as they have been raised in different environments.

They also contribute to scientific research, so they can study how species can successfully grown and developed, which can help in the wild, Seedbanks can be used to grow endangered plants for use in medical research so we don’t have to remove them from the environment. But this can lead to interbred populations and a lack of genetic diversity.

In zoos there will be an increased knowledge about the behaviour, physiology and nutritional needs of the animals, this can be used for in-situ conservation.  Zoos cannot carry out the needed research on some animals in the wild. Captive breeding can cause animals to act different to they would in their natural environment.

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Biodiversity and Endemism

Biodiversity and Endemism

Biodiversity is the variety of all living organisms in an area. It includes species diversity (the number of different species, and abundance of each species in a area) and genetic diversity (the variety of alleles within a specie). Conservation is needed to help maintain biodiversity. Endemism is when an specie is unique to a single place, such as the giant tortoise.

Species diversity can be measured, and compared to different habitats. The number of different species in an area is species richness, the higher the number of species, the greater the specie richness. But it gives no indication of abundance of each species.  Count the number of species and the abundance of each species, then use the biodiversity index to calculate the species diversity.

This is easily, Choose an area to sample, to avoid bias do it randomly. For plants use a quadrant, insects use a sweep net, for ground insects use a pitfall trap, and aquatic animals use a net.

Diversity within a specie is the variety shown by an individual of the species. Individuals of the same species vary because they have  different alleles. Genetic diversity is the variety of alleles in the same gene pool of a population. The greater the variety the greater the genetic diversity.

To measure it looks at two things, Phenotype and genotype. For phenotype look at the characteristics of the organism. Such as there is a greater genetic diversity in eye colour in northern Europe. To measure genotype you need a sample of the organisms DNA.

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Drug testing and drugs from plants

Drug testing and drugs from plants

Before drugs become available to the general public they need to be tested to make sure they work, and don’t have any horrible side effects. We know this through the past, experiments such as William withering digitalis soup,  he discovered that extracts from foxgloves could be used to treat dropsy. Withering made a chance observation, a patient suffering with dropsy made a good recovery after being treated with it, he knew foxgloves were poisonous so he used patients to find out the correct concentration of it.

Nowadays drug protocols are a lot more strict and controlled. Before using it on any live subjects computers are used to look for any side effects . Tests are then carried out on human tissue in a lab and then live animals before clinical trials can be carried out.

 

There are three phase to the clinical trials

  1. Phase one involves testing a new drug on a snall number of healthy individuals, it is done to find out a safe dosage and look for side effects.
  2. Phase two is to be tested on a larger group of patients, to see how well the drug works
  3. Phase three is when it is compared to existing treatments. It involves hundreds, or even thousands of patients. They are split into two groups, one with the new treatment, and one who receives the existing treatment.

Placebos and double blind studies are used to make clinical trials more reliable.

 

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Starch, cellulose and fibres

Starch, cellulose and fibres

Starch is the main energy storage material in plants, cells get energy from glucose. Plants store excess glucose a starch.

Starch is a mixture of two polysaccharides, these are Amylose which is a long unbranching polysaccharide. It is a coiled structure, making it compact, so it is good for storage. Amylopectin is the other, it is a long branched chain of a glucose. It side branches allow for a quick release of glucose.

Cellulose is made of long unbranched cains of Beta-glucose and is joined by glycosidic bonds. The glycosidic bonds are straight so cellulose molecules are straight. Between 50-80 cellulose chains are linked together by a large number of hydrogen bonds.

Plant fibres are made up of long tubes of plant cells, they are strong which makes them good for rope, this is due to a number of reasons, the arrangement of cellulose mircrofibrils in the cell wall, which is like an net arrangement. And  also the secondary thickening of the cell wall.

Plant fibres and starch can be used to control sustainability. Plant fibres can be used to make rope, and fabrics. These used to be made from oil which is not a renewable source. Plant fibres are renewable due to them being able to be planted and re-grown, this will maintain supply. Also materials made from plant fibres are biodegradable, as they can be broken down by microbes, but most oil products can’t!  Plants are also easier to grow and process.

Starch is found in all plants, such as potatoes and corn,  materials which are usually made from plastics can be made from starch, these are called bio plastics. This makes the product more sustainable. You can also make vehicle fuel from starch, called bio ethanol.

Plants need water and inorganic ions, they need these for a number of different functions. They are absorbed through the roots and travel up the plant xylem. If there isn’t enough water or inorganic ions then the plants will show deficiency symptoms.

 

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Plant cell structure and plant stems

Plant cell structure and plant stems

Different part of the plant stems have different functions there are two main things, these are xylem vessels and the sclerenchyma fibres.

Water is transported through xylem vessels through diffusion gradients. When water evaporates away it is called transpiration. The stream of water passing through a plant is called the transpiration stream. The water movement through the xylem provides a mass flow system for the transport of inorganic ions.

 

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Classification

Classification

Taxonomy is the science of classification. It involves naming, and organising organisms into groups based on their similarities and differences. There are seven levels of groups involved in taxonomy, they are called taxonomic groups. Organisms are first sorted into kingdoms, and then it starts to break down into more subsections. As you go down there are more groups but fewer organisms in each group.

It ends with specie, which is where there is only one organism in it. Specie can be defined as: A group of similar organisms able to reproduce to give off fertile offspring.

All species are given a unique scientific name, in latin, it is binominal word, first with the genus and second with the specie.

There are five kingdoms, these are based on general features.

Organisms can be reclassified, if once they have been revaluated, scientists agree with the new data, which shows the tentative natures of science.

There is also a three domain taxonomy being put forward. It is called molecular phyologeny. It looks at the DNA and Proteins and sees how closely related they area.

This new system suggests that the five kingdom should be changed to three, which are Bacteria, Achaea, and  Eukaryote, these are super kingdoms and go above the kingdoms. The prokaryotic kingdom has been split into Achaea and bacteria when the other four kingdoms are now all in Eukaryote.

All organisms are given a unique scientific name. this is to avoid confusion that can arise when common names are used. There is a two part Latin name, which is called binominal system. The first part of the name is genus, it is shared by all closely related species, and the second part refers to the specific specie in the genus.

Phylogenetic trees represent the evolutionary relationship based on the best existing evidence, they are consistently being revised as new data becomes available.

 

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Adaptation and evolution

Adaptation and evolution

A niche is a role of specie within a habitat. A niche a specie occupies within a habitat includes its interactions with other living organisms, and its interactions with the non-living environment. Every specie has a unique niche, and a niche can only be occupied by one specie, there is always a slight difference between the niches.

There are three ways to which an organism can be adapted to their niche:

Useful adaptations become more common within a population of species because of evolution by natural selection. Individuals within a population show variation in their phenotype, predation, disease and competition create a struggle for survival, so individuals with better adaptations will perform better and are more likely to survive.  This is an outline of Charles Darwin’s theory of evolution by natural selection. An example is the peppered moths, which showed a variation in colour, light and dark, with due to industrial revolution the populations of each varied.

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