Topic 4: Biodiversity and natural sources

biodiversity in crisis, many different species why?, KBP, niches, adaptations (behavioural, physiological, anatomical), co-adaptation, natural selection, being adaptable, gene pool, quanitifying biodiversity, species catalogue-binomial naming system, taxonomy, SYSTEM, classification is dynamic, biodiversity within a species, sources of genetic variation, species RICHNESS,EVENNESS, "hotspots", uses of biodiversity, KBP, cellulose-pg 172 & 173, xylem vessels (transport) H20 (transpiration stream) schlerenchyma fibres (support), extraction of fibres from plants, textiles /chemical defence against attack/natural antibacterials/ medicine from plants, digitalis and drug development, drug testing today, SEEDS--> STARCH, sustainability, zoos, centres for scientific research, captive breeding programmes, variation lost & conserving genetic diversity, reintroducting animals to wild, millenium seed bank! (MSB)

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  • Created by: Marie
  • Created on: 29-05-10 22:17

4.1 Why so many different species?

Species: A group of organisms with similar morphology, physiology & behaviour which can interbreed to produce fertile offspring, and which are reproductively isolated (in place time or behaviour) from other species.

Habitat: Each has a particular set of conditions which supports a distinctive combination of organisms.

Niche: The way an organism exploits its environment

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Comparing ultrastructure of plant & animal cell (p

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a-glucose & b-glucose

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(Polysaccharides) Starch & cellulose

Starch-1,6 glycosidic bonds

Cellulose-1,4 glycosidic bonds

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Cellulose & plant cell wall

Cellulose - polymer of b-glucose (long, unbranched molecule) [straight chain]

Hydrogen bond forms between OH grp of adjacent celluloses, forms bundles-microfibrils
Single H bond=weak BUT lots of H bonds in microfibril makes strong structure.

Plant cell wall formed of microfibrils wound in helical arrangement around cell &
stuck together with polysaccharide glue (hemicelluloses & pectin).

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Structure of xylem vessels and sclerenchyma fibres


  • Both impregnated with lignin
  • Both do not contain living cells (dead)


  • Xylem vessel is a hollow tube
  • Xylem vessels have perforated end walls
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Position in the stem: Xylem & Sclerenchyma


  • Both can be found in the stem of a plant


  • Xylem vessels found in vascular bundles but sclerenhyma can be found in stem/leaf or any part of the plant that needs strengthening
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Function of xylem vessels & sclerenchyma fibres


  • Both support plant structure


  • Xylem transport water & mineral ion, sclerenchyma fibres do not
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How uses of plant fibres & starch contribute to su

Starch= easily extracted from plants. Can be used:

  • adhesives, paints, textiles, plaster & toiletries (conditioners)

Thickening: Starch granules heated in H2O,swell,absorb H2O & thicken.-"Gelatinisation"

Stiffening fabrics:

Super-absorbents: Chemically cross-linked, gelalinised,particles formed- dried, rehydrated

Starch foam

Plant based products could replace oil-based plastics
Plant based plastics developed by fermentation of agricultural waste, so supermarket food packaging e.g. plastic film can be made from starch.

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Practical: Tensile strength of plant fibres

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Importance of water & organic ions to plants

H2O-Hydrogen bonding makes strong cohesion forces between H2O molecules
Water stays together going through xylem vessels.
Solvent properties:dissolved substances can be transported through xylem & phloem
High thermal stability: helps avoid rapid changes in internal environment.

Nitrate ions: make amino acids, important for plant growth (lack can show yellow)

Calcium ions: role in structure of cell, role in permeability of cell membrane (lack=stunted)

Magnesium ions: needed to make chlorophyll (lack can show yellow)

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Practical: Investigating plant mineral deficiencie

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Practical: Investigating anti-microbial properties

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Comparing historic drug testing with contemporary

William Withering's "digitalis soup": Tested "recipe" on 163 patients and recorded side effects of digitalis eg. nausea, vomiting, diarhhoea. Recovery symptom: lots of urine. Withering realised dosage was vital.

  • Applied a standard procedure to discover correct dosage 4 each patient.
  • Slowly increased till patients showed signs of vomiting etc
  • Then decreased it back; the most effective dose
  • Recorded information & after 10 yrs wrote a book

Drug testing today:

Double blind trials-Neither doctor or patient knows the drug or placebo (dummy pill).

III-phased testing: I-Whether drug absorbed metabolised & excreted as predicted

II-Tested for effectiveness

III-double-blind randomised controlled trial- valid testing & adverse effects check

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Biodiversity & endemism

Biodiversity: different types of animals and organisms inhabiting/cohabiting the Earth.

Variation of alleles within a gene pool/population.

Endemism:Species only found in a certain area

Measuring biodiversity

Species richness:The number of species present in a given habitat.

Species evenness: measures abundance of species in different habitats
BUT does not consider population size of each species.

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Biodiversity within a species

Greater variety of genotypes in gene pool, the more genetically diverse the population.

Sources of genetic variation (pg 165)

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Adaptations to environment

Behavioural: Any actions by organisms which help them to survive or reproduce.
e.g. plants growing towards the Sun maximising light received for photosynthesis.

Physiological: Features of the internal workings of organisms which help them to survive or reproduce. e.g. A plants physiological adaptation allowing it to tolerate high salt conc.

Anatomical: The structures we can see when we observe or dissect and organism.
e.g. Bodies of bumblebees show adaptatations used to collect nectar and pollen.

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Natural Selection and adaptation & evolution

Evolution: A change in ALLELE frequency in a population over a long period of time.

Natural selection--> Survival of the fittest

The mechanism where an organism adapts to changing environments over time.

  • Change in environment
  • An organism has a random mutation that benefits organism
  • More likely to survive & reproduce whilst others die out
  • Organism that survives passes on genes
  • Offspring reproduce and new adapted species are present
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Taxonomy (hierarchy)

Taxonomy is dynamic, constantly being updated with new discoveries.

Three domains based on molecular phylogeny

Hierarchy or groups:

  • Kingdom (Animalia, Plantae, Fungi, Protoctista, Prokaryotae)
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

King Prawns Count On Funny Gay Species

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Methods of conservation of endangered species

Scientific research: Centres 4 research, enable us 2 understand how 2 conserve a species


Zoos [Evaluate]

  • Captive breeding programme:
    increase no. of individual species -if no.'s low
    maintaining genetic diversity [genetic drift=less variation]
    & reintroduction to wild if possible

Keeping Studbooks-long & time consuming, have to be maticuluous

Reintroduction to wild programme

BUT-long & complicated process-needs to be taught skill-if habitat still intact.

Millenium Seed Bank!

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Could you tag it as Edexcel please,thanks :D

Great work!

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