Resourcd File

292 views

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
292
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
0
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Resourcd File

  1. 1. AS BIOLOGY UNIT 2: DEVELOPMENT, PLANTS AND THE ENVIRONMENT TOPIC 4: BIODIVERSITY AND NATURAL RESOURCES
  2. 2. SPECIES• A SPECIES IS A GROUP OF SIMILAR ORGANISMS WHICH ARE ABLE TO INTERBREED TO PRODUCE FERTILE OFFSPRING • Species are reproductively isolated • The gene pools of different species will not normally ever mix. • Every available habitat on Earth is colonised by living organisms. Somewhere between 1.4 and 1.7 million species have already been described and named. • Endemic: A species that has evolved in one area and is
  3. 3. NICHES• Species occupy different niches. A niche is where an organism lives and what it does; how it exploits its environment. • If two organisms share the same habitat, they will not tend to compete as they will occupy different niches. E.g. Barn Owls hunt at night whereas Kestrels hunt in the day. • If two organisms do occupy the same niche, the better adapted one will survive at the expense (and possible extinction) of the other. E.g. Red and Grey Squirrels.
  4. 4. BIODIVERSITY • Biodiversity is made up of three factors; genetic, species and ecosystem. It describes the variety and variability of life and the habitats they depend on. • Biodiversity: The variation of life on Earth • Genetic Diversity: The number/variety of alleles in a population/species/gene pool • Species Richness: The number of species within a certain area • Ecological Diversity: The variety of habitats and environments
  5. 5. ADAPTIONS • Anatomical Adaptions: Adaptions to do with structure • Physiological Adaptions: Adaptions to do with how the animal works inside, and how body systems operate • Behavioural Adaptions: Actions carried out by organisms which help them survive or reproduce
  6. 6. ADAPTATIONS
  7. 7. NATURAL SELECTION • Natural selection is the mechanism, first proposed by Darwin, by which organisms change over time as they adapt to their changing environments. • As a population increases in size, a greater proportion of individuals will die or fail to reproduce owing to competition for resources, such as food or space. • This striving for survival is known as the ‘struggle for existence’.
  8. 8. NATURAL SELECTION Peppered Moths
  9. 9. SURVIVAL OF THE FITTEST • In the struggle for existence there will be winners and losers • Winners are the individuals who, by chance, possess some characteristic which gives them an advantage over others. • Winners have a select advantage over others, and are more likely to survive and reproduce, passing on the advantageous alleles to their offspring. • Change in form, behaviour or physiology over generations is called evolution.
  10. 10. SURVIVAL OF THE FITTEST
  11. 11. EVOLUTION BY NATURAL SELECTION• Evolution = “a change in allele frequency in a population over time (generations)”. • For natural selection to lead to evolution, there must be some genetic variation in the population. • An allele can be selectively neutral (i.e. it has no advantage or disadvantage) but suddenly can become selectively very advantageous if and when the environment changes. • A modern example of natural selection is headline becoming resistant to head lice shampoos, therefore most headline survive and quickly breed the next resistant generation.
  12. 12. BEING ADAPTABLE• The ability of a population to adapt to new conditions will depend on: - The strength of the selection pressure - The size of the gene pool - The reproductive rate of the organism • Selection pressure: Selective pressure is any phenomena which alters the behaviour and fitness of living organisms within a given environment. The reason why an allele is favoured over others. • The current rate of climate change due to global warming is an example of selection pressure. Some organisms will survive and some will not.
  13. 13. GENE POOLS • A gene pool consists of all the alleles of all the genes present in a population. • Some alleles of each gene will be common in the gene pool and some will be rare. • Populations with a bigger gene pool (more different alleles of each gene) are said to have greater genetic diversity. • New alleles are produced all the time by mutation of existing alleles, but this is a slow and random process. • When the population of a species declines too far, some alleles are lost, and the genetic diversity of the species declines.
  14. 14. CLASSIFICATION • 5 Kingdom Classification: - Prokaryotae: No nucleus, murein cell wall, unicellular - Protoctista: Unicellular, e.g. Amoeba, yeast - Fungi: Multicellular, hetrotrophic, non-motile - Plantae: Multicellular, autotrophic, non-motile - Animalia: Multicellular, hetrotrophic, motile
  15. 15. A HIERARCHICAL SYSTEM • Kingdom Phylum Class Order Family Genus Species • Placing organisms into groups based on shared features, known as classification or taxonomy, results in a manageable number of categories and has been the principle aim of all classification systems.
  16. 16. CLASSIFICATION
  17. 17. BINOMIAL SYSTEM • All organisms are given a scientific name, for example, Arum maculatum. • The binomial system is a system in which each species was given a unique two-part Latin name. • The binomial system is still in use today. • The first part of the name, the genus, is shared by all closely related species, so all horses and zebras are in the genus Equus. • The second part of the name defines the particular species in the genus. • Together these two words make up a unique species name that is often highly descriptive. • The binomial system is universal, as it is used and recognised by all scientists all over the world.
  18. 18. WOESE’S THREE DOMAINS• In the 1960s, a scientists called Carl Woese aimed to define the evolutionary relationships of prokaryotes. • He pioneered RNA sequencing of bacteria • A decade later he noticed that one complete group of bacteria, the methanogens, completely lacked the sequences characteristic of bacteria. • He supported his ideas with additional evidence, for example the methanogens, unlike other bacteria, had no peptidoglycans in their walls. • Woese proposed that this group belongs to a new category of organisms, the Archaea. Today they survive in extreme anaerobic environments, such as hot springs. • A paper published in a scientific journal announced the new group, allowing the theory to be peer reviewed. • At first the scientific community was sceptical and dismissed Woese’s theory, but after the influential microbiologists Otto Kandler accepted his work and organised the world’s first Archaea conference in 1981, the scientific community slowly but surely started to accept the theory and recognised it’s full significance.
  19. 19. WOESE’S TREE OF LIFE
  20. 20. BIODIVERSITY WITHIN A SPECIES • Individuals within a species differ from one another - they show variation. • In all organisms that reproduce sexually, every individual has a unique combination of alleles (except identical twins and cloned individuals). • This is genetic diversity, and the greater the variety of genotypes, the more genetically diverse the population. • Genetic diversity allows the population to adapt to changing conditions so it should be conserved.
  21. 21. SOURCES OF GENETIC VARIATION • Meiosis: crossing over and independent assortment • Random mutations: changing the DNA sequence (alternation, insertion, deletion), creating new alleles. • Most mutations have no effect on the phenotype, some have harmful effects and some are beneficial. • Fertilisation: fusion of genetic material from two individuals; different combinations • Genotype: dominant alleles mask recessive ones
  22. 22. PLANT CELLS• Plant cells have a cellulose cell wall - something that animal cells do not • They have a cell membrane, a nucleus and a nucleolus, just like an animal cell codes • They have a large sap-filled vacuole, surrounded by a tonoplast membrane • In the cytoplasm, they contain all the organelles that animal cells have, except centrioles, and plus chloroplasts
  23. 23. CHLOROPLASTS• Chloroplasts are the site of photosynthesis in plant cells. Only plant cells contain chloroplasts. • Chloroplasts also contain circular DNA and small 70s ribosomes.
  24. 24. PLANT CELL WALL• The golgi apparatus produces vesicles which contain components for the new dividing cell wall. The vesicles congregate in the middle of the cell. • The first layer to be laid down is calcium pectate which forms the middle lamella. • The next layer is a a layer of cellulose which forms the primary cell wall. • A second layer of cellulose may be added, forming the secondary cell wall. • Further layers of lignin may be added. • There are holes that go through the entire cell wall, which are called plasmodesmata, through which the cytoplasm of one cell connects with it’s neighbouring cell. • A pit is a hole in the secondary cell wall through which water can
  25. 25. PLANT CELL WALL
  26. 26. STARCH• Starch is made from two polymers of glucose, amylose and amylopectin. • It is made up of alpha-glucose (α-glucose) • Amylose is a chain of thousands of glucose units. Amylopectin is a branched chain of glucose molecules with 1,6 and 1,4 glycosidic links. • It is a storage polysaccharide found in green plants, such as potatoes, rice, cereals ect. • Starch is large, insoluble and it doesn't have an osmotic effect. • We eat starch as it is a great source of energy; we break it down into glucose monomers (single sugar units).
  27. 27. STARCH
  28. 28. CELLULOSE • Cellulose is the most abundant polymer on Earth. • It is made up of beta-glucose (β-glucose) • It is a polysaccharide • All bonds are 1,4, therefore cellulose is a long, unbranded molecule. • Hydrogen bonds form between the -OH groups in neighbouring cellulose chains, forming bundles called microfibrils. • The large number of hydrogen bonds in the microfibril produces a strong structure. • Therefore the arrangement of the cellulose microfibrils in the cell wall makes it very strong but flexible.
  29. 29. CELLULOSE & MICROFIBRILS
  30. 30. PLANT FIBRES• Plants contain fibres in their stems, leaves and roots. • Fibres are specialised cells which have been thickened in their cell walls so that they can carry out particular functions. • Two examples of fibres are sclerenchyma and xylem. • Humans use fibres to make products such as clothing, paper, rope and many more. They are used as they are long and thin, flexible and strong. • Plant fibres are also used to absorb heavy metals, absorb hydrocarbons from polluted water, and they can be added
  31. 31. PLANT FIBRES
  32. 32. USES OF PLANT FIBRES • Hemp: Fibres from stem and leaf = matting, rope, coarse cloth • Cotton: Fibres on cotton seed aid seed dispersal. We use cotton as fabric. Long, thin and flexible, but strong. • Linin: Flax plant/fibres from stem = clothing, fabric. • Straw: Hats, baskets, thatching, building materials. • Wood: Xylem vessel = furniture, building material. Strength is important, density, hardness. • Coir: Fibres from coconut husks = matting
  33. 33. WATER TRANSPORT IN PLANTS 1. Water uptake in the roots: - As water moves up the xylem, it causes a low conc. of water in the cells of the root - There is a high conc. of water in the soil - Water therefore moves into the root through the root hairs by osmosis 2. Water moves as a continuous column in the xylem vessels: - When water enters the root hair it travels into the xylem vessels in the root, then into the xylem in the stem and leaves - Adhesion between water molecules and the cellulose in the xylem vessel. Greater the force, the further up the xylem the water moves. 3. Transpiration stream draws water up through the plant as it transpires from the leaf: - Water on the surface of the leaf cells evaporates into the air spaces in the leaf - This water then moves out of the leaf through the stomata by
  34. 34. WATER TRANSPORT IN PLANTS
  35. 35. MINERAL IONS • Mineral ions are present in the water in the soil. They will enter the plant through the cell roots by active transport. They will travel to cells in the plant via the xylem vessels. • Nitrates: They are a source of nitrogen, essential for the plant to be able to make amino acids (for proteins) and nucleic acids (for RNA/DNA). • Magnesium: It’s essential for the synthesis of the green pigment chlorophyll (found in chloroplasts) and is used in photosynthesis. • Calcium: Calcium is essential for the production of the middle lamella (made of calcium pectate) when the cell divides.
  36. 36. NATURAL ANTIBACTERIALS • Plants sometimes store toxic compounds in hairs on the surface of their leaves. • These chemicals are toxic to microbes and some insects, but some are attractive to us as flavouring in foods or tea (e.g. mint) • Garlic extracts have been found to destroy bacteria which cause intestinal infections. This is potentially important as some strains of the bacteria are now resistant to widely used antibiotics such as penicillin. • The active ingredient in garlic is allicin; it interferes with lipid synthesis and RNA production. Allicin is only produced when the plant is cut or damaged. • Some studies have shown that some parts of a plant tend to have greater antibacterial properties than the rest. These are typically the seed coat, fruit coat, bulb and roots.
  37. 37. MEDICINES FROM PLANTS • Many plants contain poisons, or produce them rapidly as a response to wounding. • However, ‘poison’ is a relative term and relates to the dosage necessary to cause harm to an organism. • Clearly if a chemical can kill pathogenic microbes or malignant cancer cells at a dose level which leaves humans alive, then this ‘poison’ is more likely medicine. • An enormous number of medicines are derived from chemicals originally discovered in plants. • 75-80% of the world’s population uses extracts from plants as medicine.
  38. 38. FOXGLOVE AND DROPSY • Foxglove leaves are poisonous when eaten by humans and other animals. They have a strong, bitter taste which serves as a warning. • The symptoms are dizziness, vomiting, hallucinations and heart failure. • It is a traditional folk remedy when used in moderation. It has been known for its medicinal qualities for centuries, and in particular it was used to treat a condition called dropsy. • Dropsy is when fluid accumulates in the body tissues, and is very painful and can cause a slow death. • William Withering investigated the medicinal properties of foxglove, and it became an accepted form of medicine after he published A Treatise on the Foxglove in 1775. • He realised that getting the dose right for the patient was of vital importance. He applied a standard procedure to discover the correct dosage for each patient. • He helped change the face of medical practice forever.
  39. 39. FOXGLOVE AND DROPSY
  40. 40. DRUG TESTING TODAY • Today, a potential new drug must pass a series of tests if it is to be developed into a new product. It has to be proven to be effective, safe and capable of making a profit. It can typically take 10-12 years and cost over US$1 billion to develop a new drug. 1. Pre-clinical testing: Animal and laboratory studies on isolated cells and tissue cultures 2. Clinical trials - phase I: A small group of healthy volunteers are given different doses. 3. Clinical trials - phase II: Small groups of patient volunteers (100-300) 4. Clinical trials - phase III: Large group of patients (1000-3000) split into two groups. One group receives a placebo, one group receives the drug. 5. After licensing: Trials continue to collect data about the safety and
  41. 41. WHAT’S IN A SEED?• In flowering plants, the ovule is fertilised by the nucleus from a pollen grain and develops into the seed. • The outer layers of the ovule become lignified forming a tough seed coat which protects the embryo within the seed. • In many monocotyledons, the stored food in the seed remains outside the embryo in storage tissue called endosperm. Seeds of this type are called endospermic. • In many dicotyledons the embryo absorbs the nutrients from the embryo and the food is stored in the seed leaves (cotyledons) which swell to fill the seed. • In some seeds, food is stored in the hypocotyls - the developing stalk. • When conditions are suitable, the seed takes in water through a small pore in the seed coat. Water triggers metabolic changes in the seed. Production of plant growth substances is switched on and these cause the secretion of enzymes that mobilise the stored food reserves. Starch is broken down into glucose which is converted to sucrose for transport to the radicle and plumule. Proteases break down the proteins in the food store to give amino acids, and lipases break down the stored lipids to give glycerol and fatty acids.
  42. 42. SEEDS
  43. 43. SEED DISPERSAL • Seeds come in all shapes and sizes, most of which are appropriate for wide dispersal. • Dispersal helps offspring to avoid competing with their parent plant or with each other.
  44. 44. USES OF STARCH FROM SEEDS • Thickening: when starch granules are heated in water they suddenly swell, absorb water and thicken the liquid. Custard and wallpaper paste. • Stiffening fabrics: Starch mixture applied to surface is gelatinised and then cooled, allowing bonds to form between the starch molecules. Paper coatings and cloth treatments. Adding water reverses the process. • Super-absorbents: When starch is chemically crossed-linked before it is gelatinised, particles are formed which can be dried. When rehydrated, they take up a lot of water. Nappies. • Starch foam: When the pressure at which starch is being gelatinised is suddenly raised, then released, steam forms and the starch ‘puffs’ into an expanded structure. Organic packaging, rather than plastics or polystyrene.
  45. 45. USES OF VEGETABLE OILS • Fuels: Biodiesel produced today can be used in unmodified diesel engines alternating with petroleum diesel. • It produces less sulphur dioxide than diesel, and less carbon dioxide. • It is possible to make biodiesel from waste vegetable cooking oil, or from oil crops such as rapeseed. • It is available as 100% biodiesel or a blend with fossil fuel diesel.
  46. 46. SUSTAINABILITY• Burning oil-based fossil fuels releases carbon dioxide into the atmosphere, contributing to global warming. • Oil reserves will eventually run out. • Plastics generate non-biodegradable waste, creating major waste disposal problems. • The use of plant-based products should help to reduce these problems, although burning fuel made from vegetable oil still releases carbon dioxide. • We need to consider the source of the plant product, and the energy used and pollution created during the production and transportation of the product. • Plant based plastic bags is a more sustainable alternative to plastic bags than paper bags.
  47. 47. CAPTIVE BREEDING PROGRAMMES • Zoos have an important role in the successful breeding of animals in their care. • Increasing the number of individuals of the species if numbers are very low • Maintaining genetic diversity within the captive population • Reintroducing the animals into the wild if possible • There are more than 400 zoos in Europe participating.
  48. 48. HOW GENETIC VARIATION IS LOST • Genetic Drift: In a small population, some of the alleles may not get passed on to offspring purely by chance. This change in the allele frequencies over time is known as genetic drift, and leads to a reduction in genetic variation. • Inbreeding depression: In a small population, the likelihood of closely related individuals mating increases. This inbreeding causes the frequency of homozygous genotypes to rise, with the loss of hetrozygotes. Inbreeding results in offspring inheriting recessive alleles from both parents. Many recessive alleles have harmful effects so inbreeding depression results. The offspring are less fit, they may be smaller, less likely to survive and reproduce and females may produce fewer eggs.
  49. 49. CONSERVING GENETIC DIVERSITY • Keeping studbooks: provide the raw data upon which all the breeding plans are based. Shows the history and location of all of the captive animals of that species in the places where they are co- operating in an overall breeding programme. • Individuals who breed poorly in captivity must be encouraged to breed, whilst those who are particularly good breeders must be limited in their breeding success.
  50. 50. THE MILLENNIUM SEED BANK (MSB) • The aim of the MSB is to conserve seed samples from threatened species of plants, with 10000 species already banked. • Seeds are collected from all around the world. • Most seeds are small and easy to store, and many plants produce large amounts of seeds, so collecting small samples is unlikely to harm a wild population. • Seed preservation is improving all the time as more research is carried out. Seeds survive longer if kept cool and dry. • Once the seeds identification has been verified, and they have been cleaned and dried, the seeds are stored at -20ºC. • After a month of the seeds being stored, they are taken out to be tested and germinated to ensure they can survive in the preservation conditions. Germination is then tested about every 10 years.
  51. 51. THE MILLENNIUM SEED BANK (MSB)

×