Making use of biodiversity

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  • Created by: rachelb21
  • Created on: 07-06-17 19:03

Building tall structures

  • They produce cell walls out of cellulose (a polymer made from sugar molecules)
  • Build tall collumns out of specilaised cells
  • Stiffen these cells with lignin
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How plant cells differ

  • They have a rigid cell wall
  • They contain chloroplasts
  • Contian parenchyma which is used to fill speces between cells
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Cellulose

  • Made from beta-glucose units
  • Joined by a condensation reaction
  • All glycosidic bonds are 1,4
  • They line up to form microbundles whcih are joined by hydrogen bonds between O and CH2OH groups
  • Wound in helical arrangment around the cell
  • Held together by hemicelluloses and pectins
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Tubes for transport and strength

  • Xylem- transports water and minerals and have a stiffened cell wall
  • Phloem sieve cell tubes- transport organic solvents and do not support the plant
  • Sclerenchyma fibres- stiffened cell walls provide support
  • Sclerenchyma are the outermost tube, then phloem and then xylem
  • Known as the vascular bundle
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Xylem vessels and transport

  • Cells must be waterproof
  • As the cells become lignified and stiffen (which makes it waterproof) there is autolysis of the cell contents and the tonoplast breaks down
  • This leaves empty, dead cells that fom sieve tubes
  • Water moves upwards from the roots to the shoots
  • It diffuses out through the stomata down a diffusion gradient
  • This is known as transpiration and the stream of water is known as the transpiration stream
  • Because the water is linked by cohesion and pulled up under tension this is known as the cohesion-tension theory
  • The movement of water provides a mass flow system for mineral ions as well eg. nitrate ions
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Phloem sieve tubes and transport

  • Phloem sieve tubes remain alive
  • The end walls are called sieve plates
  • Pits allow for the transfer of material between the fluid filled lumen of adjacent cells
  • Transport of organic molecules through the phloem is called translocation
  • When mineral ions ave to move from one part of the plant to another they go through the phloem as the xylem is a one way process
  • Next to the sieve tube is a companion cell that perfomrs the metabolic functions to maintain the sieve tube
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Solutes transported in and out of phloem

  • The products of photosynthesis move out through the phloem sieve tubes
  • These products are unloaded into the sinks where they are used but not produced
  • Mass transport is used to move sugar and solutes
  • Loading into the phloem increases solute concentration so water moves by osmosis into the sieve tubes from the xylem which increases hydrostatic pressure
  • When the solutes are unloaded, lowering the solute concentration, the water moves by osmosis back into sieve tubes which lowers hydrostatic pressure
  • Difference in hydrostatic pressure creates mass flow. Substances move from high to low pressure
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Xylem and sclerenchyma for support

  • Lignin gives the plant more tensile strength
  • Sclerenchyma has also been lignified
  • Strength of fibres differs depending on degree of lignification
  • Xylem also become turgid when filled with water which provides support
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Useful plant fibres

  • Plants are useful because they are long and thin, flexible and strong
  • They can be extracted by pulling them apart of by digesting surrounding tissue
  • Fibres have uses such as absorbing heavy metal poisons and hydrocarbons, textiles and biocomposites
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Chemical defences against attack

  • They have to be chemical
  • Eg. producing toxins, being camoflauge 
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Bacterial growth

  • 2 to the power of number of generations to figure out number of bacteria cells
  • Lag phase to log/exponential growth to stationary phase to death/logathermic decline phase
  • Growth only occurs when there is sufficient nutrients, ideal temp, ideal pH, no build up of toxic waste and sufficuent oxygen as bacteria relies on aerobic respiration
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Medicine from plants

  • Withering realised the importance of correct dosage
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Drug testing today

  • Pre-clinical testing: Animal studies and lab studies
  • Clinical trials phase I: small group of volunteers who are usually healthy. They confirm if the compound is being absorbed, distrubuted, metabolised and excreted by the body correctly
  • Clinical trials phase II: small groups of volunteer patients (100-300)
  • Clinical trials phase III: large group (1000-3000) is split into 2 groups, a placebo group and a real group. Must be a double-blind randomised control trial. If succesful, can move onto licensing
  • After licensing: Trials continue to collect data on effectiveness and safety of drug
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Seeds for survival

  • Seeds are adapted to: protect the embryo, aid dispersal, provide nutrition to the plant
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Starch from seeds

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