Biology AS Unit 2

unit 2 biodiversity

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  • Created by: java33
  • Created on: 13-04-11 20:28


Species-Group of individual organisms very similar in appearance in anatomy, physiology, biochemistry and genetics whose members are able to interbreed and produce fertile offspring

Habitat-place where an organism lives.

Biodiversity-variety of life the range of living organisms to be found

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Sampling Plants

Random sampling-studying a small part of the habitat and assuming it contains a representive set of species that can be applied to the whole habitat. sample sites must be chosen at random

Sampling for plants- measure by percentage of ground cover and visual survey

Random Quadrats- use abundance scale use ACFOR Scale

AbundantCommonFrequentObviousRare Observe contents of the quadrat and apply an abundance score to each species

Measure percentage cover for a point frame, 100 readings

Transect-line across habitat, take samples along the line. Large habitat-line transect, use quadrat at set intervals along the line

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Sampling Animals

Sweep Netting-small animals e.g. insects caught in net. Can use a pooter to collect animals before they fly away.

Collecting from trees-sweep net through tree branches,

Pitfall trap- Trap set in the soil to catch small animals, any nearby animals/insects to fall in container.

Tullgren funnel-collect small animals from leaf litter. Place leaf litter in funnel. A light attracts small insects.

Light Trap-Collect flying insects at night, UV light attracts insects. Under light is alcohol vessel.

Why sample?-Assess effect of human

EIA is used to estimate effects of planned development on the environment

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Measuring Biodiversity

Species Richness-Is the number of species present in a habitat

Species Evenness-Measure of the relative numbers or abundance of individuals in each species.

Estimating species richness- qualitative survey

Estimating species evenness- carry out a quantitative survey

Total Population=(C1xC2)/C3

C1=no captured C2=Second time captured C3=no of already marked animals captured

  • Simpsons Diversity Index is a formula used to measure diversity of habitat
  • D=1-[E(n/N)^2]   
  • n=no of individuals of a particular species(% cover of plants)
  • N=Total number of all individuals of all species (% cover for plants)
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Classification and Taxonomy

 Biological classification; Is the process of sorting living things into groups. Natural  classification does this by grouping things to how closely related they are. Natural classification reflect evolutionary relationships.

Taxonomy; is the study of the principles of classification

Phylogeny; is the study of the evolutionary relationships between organisms.

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The Five Kingdoms

1)Prokaryotes have no nuclues

2)Protocists-include all the organisms that don't fit into the other four kingdoms. Many are single-celled but some are multi-cellular

3)Fungi-Organisms are mostly saprophytic.Consist of a mycelium with walls of chitin

4)Plants are multicellular organisms gain their nutrition form photosynthsis

5)Animals are heterotrophic multicellular eukaryotes

Autotrophic; An organism that makes its food by simple inorganic molecules such a CO2  and H2O Heterotrophic; It gains energy from complex organic molecules. First these molecules are digested by enzymes into simple soluble molecules then they are built up into complex molecules that the organism requires Saprophytic; An organism that grows on and derives its nourishment from dead or decaying organic matter.

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Classifying Living Things

Current system:

  • Domain
  • Kingdom
  • Class
  • Order
  • Family
  • Genus
  • Species

Why classify?

  • For our convenience
  • To make the study of living things more manageable
  • To make is easier to identify organisms
  • To help us see the relationships between species
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Naming Living Things

The binomial system uses two names to identify each species the genus name and the species name. 

A Dichotomous key is a way of identifying and naming a specimen you have found, The key provides a series of questions usually with yes or no answers, eventually the questions will lead you to the name of the specimen.

Using a common name to identify species does not work:

  • The same organism may have completely different common names in different parts of one country or in two different countries
  • Translation of languages may give different names
  • The same common name may be used for different species in different parts of the world.
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Modern Classification

Classification systems were based originally on observable features but more recent approaches draw on a wider range of evidence to clarify relationships between organisms, e.g.molecular evidence

Using Biochemistry in classification       

A protein called cytochrome C is used in the process of respiration. Nearly all living organism must respire therefore nearly all organisms must have cytochrome C. Cytochrome C is not the same in all species.

  •  If the two sequences are the same, the species must be closely related
  • If the sequences are different the species must be not so closely related

All organisms use DNA and RNA. DNA provided the genetic code

  • Comparison of DNA sequences provided a way to classify species.
  • It is probably the most accurate way to determine how closely a species is related.
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Variation; Is the presence of variety- of differences between individuals

Genetic Variation-Caused by differences between the genes and the combinations of genes or alleles.

Continuous Variation:Variation in which there is a full range of intermediate phenotypes between two extremes

Discontinous Variation:Variation in which there are discrete groups of phenotypes with no or very few individuals in between

What Causes Variation:

  • Inherited or Genetic Variation
  • Environmental causes of variation
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Is a feature of that enhances survival and long term reproductive success.

Well adapted organism will be able to:

  • Find enough food or photosynthesise well
  • Find enough water
  • Gain enough nutrients
  • Defend against predators or diseases
  • survive physical conditions of its environment
  • respond to changes in its environment
  • enough energy left over to reproduce successfully

Behavioural adaptations:aspect of behaviour of an organism that helps it to survive conditions it lives in

Physiological/biohemical adaptations:correct functioning of cell processes

Anatomical adaptations:any structure that enhances the survival of the organism

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Xerophytic plants Responding to shortage of water

Behavioural Adaptations:

  • Close stomata
  • open stomata only at night
  • fold or roll leaves (reduce water vapour potential gradient)
  • open stomata to wilt so less Surface Area for sun


  • mechanism in which plant open and close stomata


  • roots shallow but cover wide area
  • roots may be long
  • stem/leaves fleshy to store water
  • leaves reduce in size less surface area
  • waxy leaves-moisture leave only through stomata
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Natural Selection

Is the selection by the environment of particular individuals that show certain variations. Individuals survive to reproduce and pass on their variations to the next generation.

Example of selective forces:

  • availability of suitable food
  • predators
  • diseases
  • physical&chemical factors

Speciation:formation of new species

  • how long:long&slow 
  • how it occurs: must be reproductive barrier

Reproductive barriers: by biochemical changes or geographical separation

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Evidence for Evolution


Armodillos(Ross in Friends :P) &Glyptodonts very similar but larger then modern species.

Recent Fossil finds:General Trend from smaller simpler organisms to larger more complex organisms. Limitaions: Not all organisms leave fossils, can be damaged.

Recent Evidence:

Biological Molecules: likely to have same biological molecules,so share orig ancestor

Protein Variation:Central part of proteins very similar across, higher organisms have extra subunits

DNA:Genes can be compared by sequencing of the bases in the DNA.

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Evoultion Today

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Conservation of Species

Extinction:when species ceases to exist, Extinction reduces biodiversity

Human Activities:

  • Hunting for Food (over-harvesting)
  • Killing for protection
  • Killing to remove competitors for our food
  • Pollution
  • Habitat destruction
  • Inadvertent introduction if new predators

Why we need to conserve:Economic and Ecological reasons and Ethical and Aesthetic reasons:

  • Regulation of atmosphere&climate
  • Formation&Fertilisation of soil
  • Recycling nutrients
  • Crop pollination
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Effect of Global Climate Change

Importance of genetic diversity- makes it possible to evolve.

Climate Change-

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Conservation in situ

Conserving a species in its normal environment

Legislation- possible to pass legislation to stop hunting,logging etc. but is specific to a particular country.

Conservation parks: Principles of choosing reserve/park:

  • Comprehensiveness-how many species represented in an area what are prevailing enviromental conditions
  • adequacy-Large enough area for long term survival

Designating an area-Advanatges:

  • plants/animals conserved in natural environment
  • permanently protects biodiversity and significant elements of natural/cultural heritage
  • facilitates scientific research
  • possible to restore ecological integrity
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Conservation ex situ

Conserving an endangered species by activities that take place outside its normal environment

Animal species: Captive breeding expensive process- the difficulties:

  • Not in natural environment so may fail to breed
  • Space limited,Limited individuals, restricts genetic diversity
  • Decrease in Genetic diversity lack of variation
  • Difficulties of reintroduction e.g. finding food in wild/being accepted

Modern Techniques:

  • Sperm Freezing
  • Reproductive physiology
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Conservation in situ

Reserves causing conflict:

  • Protected animals coming out of the reserve to raid crops e.g. maize
  • continued hunting of protected animals for food
  • illegal harvesting of timber
  • tourists feeding protected animals/leaving litter

Conservation reserves in the UK:

  • National Parks
  • National Nature Reserves
  • Sites of Special Scientific Interest
  • Local Nature Reserves


  • Must be accompanied by removing problem causing decrease
  • Are captive bred- may not be able to survive in wild/not accepted by others
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Conservation in ex situ

Plant species:

  • large number of seeds produced:can be collected without disturbing enviro
  • seeds can be stored/germinated in protected surroundings
  • seeds stored without taking too much space
  • Bred asexually


  • any collection of seeds will cause some disturbance
  • collected samples may not hold representative selection of genetic diversity
  • some species of plants may survive in different area
  •  plants bred asexually will be genetically identical-reduces genetic diversity

Seed banks: Storage of seeds

  • must be controlled conditions
  • must remove samples &germinate them periodically
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International Cooperation

EIA-Procedure to assess the likely significant effects that a proposed development may have on the environment

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is this for EDEXCEL?



No sorry its for OCR but if its got the stuff for Edexcel then use it :)

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