SNAB topic 4

• How do zoos/seed banks preserve genetic diversity?

  ZOOS

  •Animals are selected to prevent inbreeding between closely related individuals

  
  

  •A STUD BOOK is used to select individuals for mating and record all breeding events

  
  

  •There is an exchange of animals and gametes between zoos.

  
  

  SEED BANKS

  •Seed banks collect seeds from various (endangered/rare/important) plant species.

  
  

  •The seeds are cleaned, dried and frozen, which preserves genetic material.

  
  

  •Seed banks actively participate in the exchange/distribution of seeds to be grown or conserved somewhere else.

  
  

  •Research is made behind the correct collection storage and germination of the seeds to enhance conservation efforts.
• 4.1 Know that over time the variety of life has become extensive but is now being threatened by human activity.


  Variety has become extensive but is now being threatened by human activity such as deforestation.
• 4.2 i) Understand the terms biodiversity and endemism.


  Biodiversity- the variety of living organisms

  Endemism -the state of a species being unique to a geographical location

  
• 4.2 ii) (PAR T A) Know how biodiversity can be measured within a habitat using species richness and within a species using genetic diversity by calculating the heterozygosity index


  Species richness:the number of different species in a habitatSpecies evenness:Abundance of each species
• 4.2 ii) (PART B) Know how biodiversity can be measured within a species using genetic diversity by calculating the heterozygosity index

  Genetic diversity:The number of alleles in a gene pool

  Heterozygosity index(Number of heterozygotes)÷(Total number of individuals in the population)
• 4.2 iii) Understand how biodiversity can be compared in different habitats using a formula to calculate an index of diversity

  
• 4.3 Understand the concept of niche and be able to discuss examples of adaptation of organisms to their environment


  Niche:The role a species takes within a communitySpecies which share the same niche compete with each other, leaving the better adapted species behind. (natural selection)

  AdaptationsBehavioural,improving chance of survival/reproduction e.g. mating callsAnatomical, external or internale.g. Camouflage, e.g. long loops of Henle in kidneys of desert mammals, allows them to retain waterPhysiological -processes e.g. regulation of blood flow through the skin e.g. toxin/antifreeze proteins
• 4.4 Understand how natural selection can lead to adaptation and evolution.


  1)Random mutationsin a population2)Variationof phenotypes/Genotypes3) Environmental change poses as a selection pressure4) Some individuals areadvantageddue to their phenotype5) This allows them to survive and reproduce,passing advantageous alleles to offspring6) Over time, frequency of alleles in a population changes
• 4.5 i) Understand how the Hardy-Weinberg equation can be used to see whether a change in allele frequency is occurring in a population over time.


  p + q = 1

  
• 4.5 ii) Understand that reproductive isolation can lead to accumulation of different genetic information in populations, potentially leading to the formation of new species.


  Reproductive isolation--> Accumulation of different alleles in two populations--> eventually speciation can occur

  Speciation may beallopatric(geographic isolation) orsympatric(non-geographic isolation e.g. behavioural, anatomical, temporal, gametic)
• 4.6 i) Understand that classification is a means of organising the variety of life based on relationships between organisms using differences and similarities in phenotypes and in genotypes, and is built around the species concept.

  Organisms are studied based on their similarities/differences

  
  

  Domain, kingdom, phylum, class, order, family, genus, species

  
• 4.6 ii) Understand the process and importance of critical evaluation of new data by the scientific community, which leads to new taxonomic groupings, including the three domains of life based on molecular phylogeny, which are Bacteria, Archaea, Eukaryota.


  New data about organisms werecollected, analysed and peer reviewed.New discoveries such as genotype determination lead to better clarification.

  Eventually,phylogeny(evolutionary history) andmolecular phylogeny(DNA/protein history comparison) proved itself as evidence supporting the case for 3 domains of life.Prokaryota,Archaeaand Eukaryota

  Eukaryotes: Plants, animals fungiProkaryotes: bacteria, protozoa

  
• 4.7 Know the ultrastructure of plant cells

  
• 4.7 Know the ultrastructure of plant cells (cell walls)

  Cell walls are the rigid outermost layer made of cellulose fibrils, stacked and held together by a matrix. Some cell walls are fortified with lignin

  supports plant

  
• 4.7 Know the ultrastructure of plant cells (chloroplasts)

  Thylakoid stacks (grana), stroma, matrix, double membrane, inter membrane space

  
• 4.7 Know the ultrastructure of plant cells (amyloplasts)

  Membrane bound organelles consisting of starch granules

  
  

  Storage of starch grains

  
• 4.7 Know the ultrastructure of plant cells (tonoplast/vacuole)


  Spaces enclosed by a membrane in cytoplasm are called vacuoles.Tonoplast is the name of the membrane around the vacuole.

  Maintainsturgidity. Theystore/breakdown waste products

  
• 4.7 Know the ultrastructure of plant cells (plasmodesmata)


  Cytoplasmic bridge between two adjacent plant cells

  Enablestransportandcommunication between cells.

  (these are similar to gap junctions present in animal cells)

  
• 4.7 Know the ultrastructure of plant cells (pits)

  Pit= depression in cell wall

  Two adjacent cells (on top of each other) forms a pit pair.

  Enables transport between adjacent cells

  Not found in animal cells
• 4.7 Know the ultrastructure of plant cells (middle lamella)

  Cementing material between plant cells

  Made ofcalcium pectateandmagnesium pectate.

  Provides stability.

  
• 4.8 Be able to recognise the organelles in 4.7 from electron microscope (EM) images.
• 4.9 (PART A) Understand the structure and function of the polysaccharids starch


  StarchStarch is made of amylose & amylopectinα-glucose units- both bonding OH groups on the ring face down

  Amylose- α 1-4 glycosidic bond-unbranched, coiled

  Amylopectin-α 1-4 glycosidic bonds AND α 1-6 glycosidic bonds at branch point.

  
• 4.9 (PART B) Understand the structure and function of the polysaccharide cellulose, including the role of hydrogen bonds between β-glucose molecules in the formation of cellulose microfibrils.

  CelluloseMakes the cell wallBeta glucose units-one bonding OH group on the ring faces down, the other faces up

  Long, linear/unbranched chains of β-glucose, joined byβ 1-4 glycosidic bonds

  Microfibrils, formed when (50-80) chains are linked together by large numbers ofhydrogen bondsto provide structural support.
• 4.10 Understand how the arrangement of cellulose microfibrils and secondary thickening in plant cell walls contributes to the physical properties of xylem vessels and sclerenchyma fibres in plant fibres that can be exploited by humans.


  Plant fibres such asxylem vesselsandsclerenchyma fibresare made of long tubes.

  Microfibrils in the cells walls are arranged like a net. They are held together by a matrix.

  Secondary thickening-adding more lignin over time as plant grows

  Uses of plant fibresRopes or fabrics, as they are strong
• CORE PRACTICAL 6:

  Identify sclerenchyma fibres, phloem sieve tubes and xylem vessels and their location within stems through a light microscope.


  EquipmentPlant sampleCoverslipMounted needles + forcepsToluidine blueGlycerol(Filter paper, watch glass, coverslip)

  Method•Place the plant sample on watch glass.•Pick out one/two vascular bundles and place on slide•Tease vascular bundles apart with needles•Add drop of stain, leave for a few mins•Blot off extra stain•Add drop of glycerol•Examine under Low, medium and high

  ObservationsXylem=long elongated tube like cells, walls thickened in spiral/ring formation. WIDER DIAMETERPhloem sieve tube elements= also elongated, thin walls. Sieve plates visible as perforated cell walls.Sclerenchyma -Long slender, HEAVILY STAINED. Outer edge of bundle.Phloem-Smaller cells, more circular/rectangular than xylem. Cell walls less distinct.

  
• 4.11 Know the similarities and differences between the structures, position in the stem and function of sclerenchyma fibres, xylem vessels and phloem.


  SclerenchymaProvides supportLong, tube like, no pits, thickened with lignin.

  Xylem vesselsProvides support/transport of water & ions.Long, tube like, with pits.

  Phloem tissueEnables translocation of organic solutes.

  Sieve tube elements:Living cell, lacks nucleus, joins to form sieve tubeCompanion cells: Have a nucleus/organelles so canprovide energy to help sieve tube elementsto transport actively.

  
• CORE PRACTICAL 7:

  Investigate plant mineral deficiencies.


  Equipment•5 plants•Test tube rack•Ruler•Solution containingall minerals•Solution containing all except magnesiumions•Solution containingall except nitrateions•Solution containingall except calciumions•Solution containingno minerals•Tin foil

  Method1) Half fill test tubes with each solution2) Cover top with foil3) Measure initial lengths of each seedling4) Push roots of plantlet into solution, repeat for each tube5)Wrap all tubes in foil (except for on top)6) Place test tube rack on sunny window sill7) Measure the length of the plants every other day, for two weeks

  ControlThe controls for this practical are the solution with all minerals, and the solution with no minerals.

  ObservationsMagnesium deficiency-stunted growth, yellowed leavesas chlorophyll cannot be made. Reddish brown tint

  Nitrate deficiency-yellowed leaves and stunted growth

  Calcium ions-stunted growth, soft plantlacking support as cell walls are weakened.

  No minerals-Dead plantAll minerals- healthy plant, full growth
• 4.12 Understand the importance of water and inorganic ions (nitrate, calcium ions and magnesium ions) to plants.

  Water•Regulating temperature•Transporting minerals•Photosynthesis•Maintain structural rigidity

  Nitrate ions•DNAproduction•Proteinproduction•Chlorophyllproduction

  Magnesium ions•Needed forchlorophyll production•Needed to create middle lamella

  Calcium ions•Needed to create middle lamella•Needed to createcell walls
• CORE PRACTICAL 8:

  Determine the tensile strength of plant fibres.


  EquipmentStems of chosen plantsSharp knife/scalpelPaper towelsClamp standsA set of same type of weightsWhite tile

  Method

  1) Remove fibres*2) Clamp fibre between two clamp stands3) Add mass in middle, increase in increments4) Note down mass required to snap fibre5) Compare between different plants

  * Soak plants if fibres are not easily obtainable
• 4.13 Understand the development of drug testing from historic to contemporary protocols, including William Withering's digitalis soup, double blind trials, placebo, three-phased testing.

  Digitalis soup-Trial and error

  Three phased testing1) test on healthy individuals. find side effects.2) test on large numbers of patients3) test on thousands of patients, compare existing and new treatment.

  Placebo-Inactive substances, looks like a drug but isn't. Acts as a control to compare how effective the new drug is.

  Double blind studyNeither patient nor doctor knows who has the placebo/drug --> No bias.
• 4.14 Understand the conditions required for bacterial growth.

  •Source of nutrients

  •Supply of oxygen for aerobic bacteria

  •Optimum temperature/pH
• CORE PRACTICAL 9:

  Investigate the antimicrobial properties of plants, including aseptic techniques for the safe handling of bacteria.


  EquipmentPestle and mortarPetri dish with agar seeded with E.coliEthanolSterile pipettes.GarlicMintPaper discs

  Method1) Crush garlic, add 10cm3 of alcohol. Shake for 10mins2) Do same for mint3)Pipette 0.1cm3 of each solution onto separate paper discs4) Place the discs on agar5) Close each disc, seal with tape, leave gap for oxygen6) Leave to incubate overnight7) Measure the radii of the clear zones of inhibition, compare with control disc

  aseptic techniques:-disinfected surfaces-inoculating loop with-incubation below 37 degrees C to prevent pathogens from thriving-usingflamedinoculating loops to transfer bacteria

  ControlAdd a disc that has 0.1cm3 of distilled water on it.

  CalculationCalculate area of zone of inhibition-->A=πr² .Calculate mean using repeat data for each plant disc.

  ConclusionGarlic has a larger zone of inhibition, it has more antimicrobial properties.
• 4.15 Understand how the uses of plant fibres and starch may contribute to

  sustainability, including plant-based products to replace oil-based plastics.


  Plant fibres can be used for rope/fabric because they are biodegradable and easier to grow

  Starch can be used instead of oil based plasticsto make products such as vehiclebiofuel.This is more sustainable because they are easier to regrow.
• 4.16 Be able to evaluate the methods used by zoos and seed banks in the

  conservation of endangered species and their genetic diversity, including

  scientific research, captive breeding programmes, reintroduction programmes and education.


  Protected environments:"On site conservation", controlled/restricted areas conserves biodiversity

  Zoos/botanical gardens"Off site conservation" . Allow for captive breeding, conservation & reintroduction when possible.Reproductive/nutritional studies can be carried out in zoo.

  Seed banksAllows conservation of species when habitat is not available and reintroduction when habitat is available.

  Zoos/seed banks help educate people about the importance of wildlife/growing plants from seeds.