Biodiversity and Natural Selection

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Plants as a Natural Resource

  • Plants provide macronutrients (carbohydrates, lipids and proteins).
  • They also provide micronutriets (vitamins and minerals).
  • They store starch, which is a good energy source.
  • Rice, wheat, potato and maize are examples of staple foods.
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Plants as a Natural Resource

  • Selective breeding is breeding only invididual plants with desired characterists/features.
  • Someestimes called artificial selection.
  • The selectively bred plants give higher yields, resistant to diseases, resistant to insect pest damage, and can survive harsher conditions
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Plants as a Natural Resource

  • Poorer farmers cannot afford to grow varieties of crop that have highly desired characteristics, as there are only a few varieties that have enough quality to be sold.
  • Genetically modified plants are engineered to prevent them from breeding (so that they don't cross breed).
  • This means that farmers have to continuously buy new seeds or seedlings.
  • This is difficult for poorer farmers. 
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Plants as a Natural Resource

  • The thickening of plant stems, by sclerinchyma and lignification of xylem, makes thems strong and resistant to tensile and compressive forces.
  • This is why wood has such good construction features. 
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Plants as a Natural Resource

  • Fibres can be removed from plant stems by retting.
  • Field retting is when plant stems are cut or pulled up and left in a field to rot; microbial actions breaks down the stalks, and fibres are collected.
  • Water retting is the same, except rotting occurs in water by aqeuous bacteria and fungi.
  • Water retting produces more uniform, high quality fibres, but is more expensive and produces more waste
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Plants as a Natural Resource

  • Cotton fibres are produced in pure form, not within a matrix of other materials. 
  • This means that cotton does not need retting, it can be picked straight from the plant, unlike jute and hemp. 
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Plant Pharmacies

  • Scientists extract the active ingredient of a medicinal plant instead of using the whole plant.
  • This removes impurities in the whole plant.
  • Ingredient is extracted and purified to make it more effective.
  • Also means we can use more accurate dosages.
  • Ingredient is synthesised and modified, so that it can produced on an industrial scale. 
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Modern Drug Development

  • Scientists identify and extract active ingredient.
  • Impurities are removed, drug is purified and modified so its effectiveness is optimised.
  • New compound is tested in cell/tissue cultures to see if drug has desired effect.
  • Drug moves out of research and into development.
  • The drug is tested on animals to ensure no risk of breaking down into something toxic.
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Modern Drug Development

  • Phase 1 trials: drug given to small number of healthy volunteers, to investigate side effects.
  • Phase 2 trials: drug is given to patients affected by the disease. Between 100-500 volunteers given drug.
  • Phase 3 trials: Over 5000 patients normally used. 
  • Phase 2 and 3 trials are double-blind, which means neither the doctor nor the patients know whether drug is real or a placebo
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Withering's Drug Work

  • Withering tested digitalis on patients are a pain killer.
  • His method was scientific in that he: identified the active ingredient, tested on a large number of patients over many years, made careful observations of methods of preparation aand recording results including side effects.
  • His method was unacceptable in that: He experimented on patients without testing for safety and effectiveness in other ways beforehand, and experimenting with dosages that could kill patient.
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Biodiversity

  • Biodiversity is the variety of living organisms in an area.
  • Two types: species and genetic.
  • Species diversity is the number of different species and the abundance of a species in an area. 
  • Genetic diversity is the variation of alleles within a species
  • Endemism is when a species is unique to one area in the world.
  • E.g the giant touroise is endemic to to the Galapogous island.
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Biodiversity

  • Biodiversity is the variety of living organisms in an area.
  • Two types: species and genetic.
  • Species diversity is the number of different species and the abundance of a species in an area. 
  • Genetic diversity is the variation of alleles within a species
  • Endemism is when a species is unique to one area in the world.
  • E.g the giant touroise is endemic to to the Galapogous island.
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Biodiversity

  • Endemic species are very susepitble to extinction, because they are used to having no competition for food in their unique habitat.
  • Species richness is the amount of different species in an area (like half of species diversity).
  • Species richness can be measured simply by counting the number of different species in an area.
  • Species diversity can be measured by counting the number of different species and the number of animals in each species. 
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Biodiversity

  • It would be very time consuming and expensive to count all the species and their relative abundancies, so instead we use a sample area.
  • Choose area to sample, to avoid bias the sample to be random
  • Count the number of species and their relative abundancies, using a quadrat, sweep net, pitfall trap or a net.
  • Repeat the process in different areas to improve relaiblity.
  • Use results to estimate species richness/diversity.
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Biodiversity

  • Indivuals in the same species may vary because they have different alleles.
  • Genetic diversity is the variety of alleles in the gene pool of a species.
  • A gene pool is the complete set of alleles in a species. The greater the variety of alleles in a gene pool, the greater the genetic diversity. 
  • By looking at the different phenotypes within a population of a species, you can see the diversity of alleles in a species.
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Biodiversity

  • Another way of measuring genetic diversity is through the genotypes of animals in a population.
  • Samples of an organisms DNA can be taken and a sequence of bases analyses.
  • The order of bases different alleles is slightly different.
  • By doing this for many organisms in a species, you can look at the genetic similarities and differences, and count how many different alleles there are in the species for one characteristic in a gene pool. 
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Biodiversity

  • Reduction or extiction of a species or the reduction in genetic diversity of a species causes a reduction in the glab biodiversity. 
  • Zoos and seed banks help to conserve endangered species.
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Biodiversity

  • Seed banks store the seeds of endangered plants.
  • They help to conserve biodiversity.
  • If the plants become extinct in the wild, seeds from the seed bank can be used to replenish the species.
  • They also help conserve genetic diversity, because they store a range of seeds from plants with a range of genetic characterists (different alleles). 
  • They create cool, dry conditions for storage.
  • Live seeds are cleaned and sterolised.
  • Test seeds for viability (X-ray)
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Biodiversity

  • Zoo's have captive breeding programs where animals of the same endangered species are bred in controlled environments. This increased their population.
  • Organisms from zoo's can be reintroduced into the wild. 
  • This reintroduction can save not only an endangered species, but species that rely on the endagnered species.
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Biodiversity

Zoo's maintain genetic diversity by:

  • Collecting sperm of endangered species.
  • Storing it in sustainable conditions.
  • Captive breeding programs.
  • Careful mate selection for breeding.
  • Ultimate aim of reintroducing captive bred animals into the wild habitat.
  • Recording breeding in a stud book.
  • NOTE: some animals find it difficult to live in wild one reintroduces from zoo life. 
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Natural Selection

  • Individuals in a population show variation in their phenotype.
  • Predation, diseases and competition create a struggle for survival.
  • Indivuals with better adaptations are more likely to survive, reproduce and pass on their advantagous adaptations to their offspring.
  • Over time the number of individuals with the advantageous adaptations increases.
  • Over generations this leads to evolution, as the advantageous adaptations become common.  
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Comments

Marius

This is great! Really did all the work for me so I didn't have to do any!


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