Advanced Higher Biology - PowerPoint PPT Presentation

Loading...

PPT – Advanced Higher Biology PowerPoint presentation | free to download - id: 3b5b8e-NjFkM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Advanced Higher Biology

Description:

Advanced Higher Biology Environmental Biology Unit Anderson High School CR Environmental Biology The Environment and its ecosystems have political, economic and ... – PowerPoint PPT presentation

Number of Views:615
Avg rating:3.0/5.0
Slides: 65
Provided by: andersonS
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Advanced Higher Biology


1
Advanced Higher Biology
  • Environmental Biology Unit
  • Anderson High School
  • CR

2
Environmental Biology
  • The Environment and its ecosystems have
    political, economic and ethical dimensions due to
    their impact on the human species
  • This unit will help you to understand the
    interactions between organisms and their
    environment, and the human influence on the world
    around us

3
Advanced Higher Assessment
  • Environmental Biology is a 40 hour Unit
  • Involves lectures, tutorials, discussions,
    practical work, presentations and assessments all
    to help with the learning process and in
    preparation for University Life
  • NAB (sit in March after Prelims)
  • Assessment 2 ½ Hours (Feb May)

4
Environmental Biology
  • 10 Topics 1 Energy Fixation
  • 2 Circulation of Nutrients
  • 3 Biotic Interactions
  • 4 Symbiotic Relationships
  • 5 Costs/Benefits of Competition
  • 6 Survival Strategies
  • 7 Succession
  • 8 Intensive Food Production
  • 9 Increase in Energy Needs
  • 10 Pollution

5
1. Energy Fixation
  • Energy is required by all organisms for cellular
    activities, growth reproduction
  • The fixation of energy occurs in photosynthesis
    by autotrophs
  • Autotrophs (are producers) that change light
    energy into chemical energy to make organic
    molecules
  • Heterotrophs (are consumers) that must feed on
    other plants or animals to get a ready made
    supply of organic molecules
  • Saprotrophs (are decomposers) that use the
    organic materials from waste and dead organisms
    as an energy source
  • Autotrophs
  • Heterotrophs
  • Saprotrophs

6
Energy Calculations
  • Gross Primary Productivity (GPP) is the total
    amount of light energy converted to chemical
    energy by autotrophs
  • Not all energy produced by autotrophs is
    available for consumers as autotrophs use up some
    of the food in respiration for their own
    metabolic needs
  • Net Primary Productivity (NPP)
  • NPP GPP energy used in respiration.
  • Therefore NPP is the energy available to all
    other organisms in an ecosystem after producer
    respiration
  • Primary productivity is measured using the
    biomass of vegetation added to a given area in a
    given time e.g. g/m2/year

7
Feeding Relationships
  • Herbivores feed on plant material Carnivores
    feed on animals
  • Decomposers are organisms (e.g. bacteria and
    fungi) (saprotrophs) that breakdown organic
    matter by secreting digestive enzymes
  • Detritivores are organisms (e.g. earthworms
    woodlice) that feed on detritus (decomposing
    material)
  • Primary consumers are herbivores that feed
    directly on producers
  • Secondary consumers are carnivores that feed on
    primary consumers
  • Tertiary consumers are carnivores that feed on
    secondary consumers
  • A trophic level is a feeding level present in a
    food chain or food web
  • Energy flow in a food chain or food web is
    represented by arrows
  • Energy transfer is not very efficient. Only 10
    of energy at one trophic level is passed on to
    the next level

8
Biological Pyramids
  • Pyramids of numbers represent the number of
    organisms at each trophic level
  • Pyramids of biomass represent the mass of
    organisms at each trophic level
  • Pyramids of productivity represent the energy
    available at each trophic level
  • In an ecosystem, productivity, biomass and
    numbers of organisms tend to decrease at each
    trophic level
  • The ultimate loss of energy is in the form of
    HEAT (from respiration)

9
2. Circulation of Nutrients
  • Decomposition is the breakdown of organic matter
    with the release of inorganic nutrients into the
    surrounding soil
  • Inorganic ions are released from decomposing
    matter in a process called mineralisation
  • Decomposers and Detritivores are involved in
    decomposing organic matter
  • Undecomposed material is called litter
  • Completely decomposed matter is called humus
  • Invertebrate detritivores (e.g. worms) increase
    the decomposition rate as they reduce the
    particle size of the detritus, making it easier
    for the decomposers (bacteria fungi) to break
    down detritus to form humus
  • Decomposers are the ultimate releasers of energy
    and carbon dioxide fixed in photosynthesis
  • Nutrients must be recycled for the primary
    producers to use

Detritivores (e.g. worms)
Decomposers (e.g. wood fungi)
10
Nitrogen Cycle
  • There are 4 main stages Fixation,
    Nitrification, Denitrification and Ammonification
  • 1. Fixation is when Atmospheric Nitrogen is
    converted to Ammonia
  • Free living cyanobacteria in the soil fix
    nitrogen
  • Rhizobium bacteria in the root nodules of legumes
    fix nitrogen
  • Cyanobacteria Rhizobium bacteria have an enzyme
    complex called nitrogenise which converts
    atmospheric nitrogen to ammonia with the use of
    ATP
  • The plant (legume) and the Rhizobium bacteria
    produce a molecule called Legheamoglobin. This
    molecule binds with oxygen which is really
    important as nitrogen fixation is an anaerobic
    process
  • 2. Nitrification is when Ammonium is converted to
    Nitrites then to Nitrates
  • Nitrosomonas and Nitrobacter bacteria carry out
    this process
  • The nitrates are then used by plants to make
    proteins nucleic acids (assimilation)
  • Nitrates can be lost by leaching and denitrifying
    bacteria (Pseudomonas)
  • 3. Denitrification is when Nitrates are converted
    back to Atmospheric Nitrogen
  • Denitrifying bacteria (Agrobacterium) are
    involved
  • 4. Ammonification is when organic nitrogen in
    Proteins is converted into ammonia by decomposers
    (bacteria fungi)
  • Water saturation and anaerobic conditions affect
    the cycling of nitrogen

11
The Nitrogen Cycle
12
The Nitrogen Cycle (again)
13
Nitrogen Cycle
14
Nitrogen Fixation
  • Fixation is when Atmospheric Nitrogen is
    converted to Ammonia
  • Free living cyanobacteria in the soil fix
    nitrogen
  • Rhizobium bacteria in the root nodules of legumes
    fix nitrogen
  • Cyanobacteria Rhizobium bacteria have an enzyme
    complex called nitrogenise which converts
    atmospheric nitrogen to ammonia with the use of
    ATP
  • The plant (legume) and the Rhizobium bacteria
    produce a molecule called Legheamoglobin. This
    molecule binds with oxygen which is really
    important as nitrogen fixation is an anaerobic
    process

Cyanobacteria
Rhizobium
Root Nodules
Clover
15
Nitrification
  • Nitrification is when Ammonium is converted to
    Nitrites then to Nitrates
  • Nitrosomonas and Nitrobacter bacteria carry out
    this process
  • The nitrates are then used by plants to make
    proteins nucleic acids (assimilation)
  • Nitrates can be lost by leaching and denitrifying
    bacteria (Pseudomonas)

16
Denitrification
  • Denitrification is when Nitrates are converted
    back to Atmospheric Nitrogen
  • Denitrifying bacteria (Agrobacterium) are
    involved
  • Nitrates Atmospheric Nitrogen

Agrobacteria
17
Ammonification
  • Ammonification is when organic nitrogen in
  • Proteins is converted into ammonia by
  • decomposers (bacteria fungi)
  • Nitrogen Ammonia

18
Bacteria involved in Nitrogen Cycle
  • Nitrogen Fixation - Cyanobacteria
    Rhizobium(legumes)
  • Nitrogen Ammonia
  • Nitrification - Nitrosomonas and Nitrobacter
  • Ammonium Nitrites Nitrates
  • Denitrification Agrobacterium Pseudomonas
  • Nitrates Atmospheric Nitrogen
  • Ammonification Bacteria Fungi
  • Nitrogen Ammonia

19
Phosphorus Cycle
  • Phosphorus Cycle
  • Phosphorus is added to the soil by the weathering
    of rocks, taken up by primary producers and
    returned by decomposition
  • Phosphorus is a main component of nucleic acids,
    phospholipids, ATP, bones, teeth
  • Phosphorus is organic, doesnt have a gaseous
    form, so the only inorganic form is phosphate
  • Phosphate is a limiting factor in the
    productivity of aquatic ecosystems
  • Phosphate enrichment can lead to eutrophication
    (algal blooms)
  • Eutrophication is when plant and algal growth is
    over stimulated in a water ecosystem.
  • Fertilisers running into water systems, added
    nitrogen or phosphate to lochs etc can cause this
    over stimulation
  • The plants and algae eventually die, which
    reduces the oxygen in the water, so fish and
    other organisms eventually die

20
Phosphorus Cycle
21
3. Biotic Interactions
  • Biotic components of an ecosystem are living
    factors e.g. predation, disease, food supply,
    competition
  • Abiotic components of an ecosystem are non-living
    factors e.g. temperature, light intensity, soil
    pH, availability of water
  • Density dependent factors are factors that can
    regulate a population. These factors increase as
    population size increases e.g. predation,
    disease, food supply, competition
  • Density independent factors are factors that can
    regulate a population. These factors are
    independent of population size e.g. hurricanes,
    forest fires
  • Interspecific Competition is interactions between
    individuals of different species
  • Intraspecific Competition is interactions between
    individuals of the same species and is more
    intense that Interspecific Competition
  • Predator/Prey interactions are cyclical, but
    slightly out of phase with each other due to the
    changes in predator numbers lagging behind those
    of the prey (e.g. Lynx Snowshoe Hare)
  • Predators have a role in maintaining species
    diversity in ecosystems by controlling the
    numbers of more dominant competitors in an
    ecosystem, thus allowing weaker competitors to
    survive

22
Defence Against Predation
  • 3 Main Defences-
  • 1. Camouflage Camouflage is when the organisms
    colouring or pattern allows it to merge into
    the background
  • a) Crypsis hiding to reduce the risk of
    predation
  • b) Disruptive Colouration patterns on body
    dont match outline
  • 2. Warning Colouration Warning Colouration is
    when organisms are brightly coloured to warn
    predators that they are dangerous to eat
  • 3. Mimicry Mimicry is when an organism bears a
    resemblance to a harmful species
  • a) Batesian mimicry is when an edible or
    harmless species mimics a poisonous or
    harmful species
  • b) Mullerian mimicry is when 2 or more
    species have evolved to have the same or
    similar warning signals

23
Camouflage
  • Camouflage is when the organisms colouring or
    pattern allows it the
  • merge into the background. 2 Types-
  • a) Crypsis hiding to reduce the risk of
    predation (e.g. stick insects)
  • b) Disruptive Colouration patterns on body
    dont match outline (e.g. zebra)

24
Warning Colouration
  • Warning Colouration is when organisms are
  • brightly coloured to warn predators that they
  • are dangerous to eat!
  • e.g. yellow and black markings of wasps

25
Mimicry
  • Mimicry is when an organism
  • bears a resemblance to a harmful
  • species
  • a) Batesian mimicry is when an edible or harmless
    species mimics a poisonous or
  • harmful species (e.g. harmless robber fly has
    similar colourings to a wasp)
  • b) Mullerian mimicry is when 2 or more species
    have evolved to have the same or
  • similar warning signals (e.g. social wasps
    and caterpillars of cinnabar wasps)

Harmless Robber fly
Harmful wasp
Wasp
Cinnabar Caterpillar
26
Grazing
  • A grazer is defined as any
  • species that moves from one
  • victim to another, feeding on a
  • part of each victim but
  • doesnt actually kill it
  • Moderate grazing can increase
  • the biodiversity of species
  • present as grazing reduces the
  • number of dominant grasses
  • and other plants with basal
  • meristems, which allows weaker
  • competitors to survive

27
Competition
  • Competition is when organisms require the same
    resource
  • Interference Competition results when two or more
    species actually fight over resources and one
    species prevents another species from using the
    resource
  • Exploitation Competition results when two or more
    species use the same resources, thus reducing the
    resources available for all.

28
Niche
  • For AHigher the term Niche means-
  • the feeding role that a species plays within a
  • community
  • A fundamental niche is the set of resources a
  • species is capable of using if there is no
  • competition
  • A realised niche is the set of resources
  • actually used by the species due to
  • competition
  • Resource partitioning is the dividing up of
  • each resource by species specialisation and
  • adaptation (e.g. different lengths of beaks in
  • wading birds)
  • Competitive Exclusion Principle is when two
  • species compete for the same resource, but

29
Resource Partitioning
30
Exotic Species
  • Exotic species are species that have been
    introduced deliberately or by accident and it may
    have damaging effects on native species e.g. New
    Zealand Platyhelminth (flatworm)
  • This worm has a detrimental effect on earth worms
    and thus effects soil ecosystems

31
4. Symbiotic Relationships
  • Symbiosis is the relationships between organisms
    of different species that show an intimate
    association with each other, involving at least
    one species gaining a nutritional advantage
  • Examples of Symbiosis are
  • Parasitism, Commensalism, and Mutulaism

32
Parasitism
  • Parasitism is a biotic interaction which is
    beneficial to one species (the parasite) and
    detrimental to the other species (the host) e.g.
    tapeworm and humans
  • An obligate parasite cannot survive without the
    host organism
  • A facultative parasite can live with or without
    the host
  • Endoparasites live within a hosts body e.g.
    tapeworms, liver flukes, malarial parasites
  • Ectoparasites live on the surface of the host
    e.g. ticks, fleas, leeches

Ectoparasite Dog Tick
Endoparasite human tape worm
33
Host-Parasite Balance
  • A balance exists between the parasite and the
    host so that there is a relatively stable
    relationship
  • Parasites can be transmitted to new hosts can be
    by -
  • direct contact e.g. head lice and humans touching
    each other
  • resistant stages e.g. liver fluke in snail hosts
    are dormant in water, then sheep drink water and
    the fluke becomes active
  • secondary hosts (vectors) e.g. mosquitoes
    transmit the malarial parasite
  • Host-parasite specificity gives evidence of
    evolutionary adaptation e.g. immunity

34
Commensalism
  • Commensalism is a biotic interaction beneficial
    to one species (commensal) and the other species
    in unaffected
  • Egrets feed on the ectoparasites on back of
    elephant
  • Clownfish feed on scraps of dead prey of sea
    anemone

35
Mutualism
  • Mutualism is a biotic interaction beneficial to
    both species.
  • The anemone is taken to new habitats when the
    crab moves so the crab gets to new food sources
  • The crab gains protection from predators from the
    anemones stinging cells

36
5. Costs/Benefits of Interactions
  • Competition (-/-)
  • Predation (/-)
  • Parasitism (/-)
  • Commensalism (/0)
  • Mutualism (/)
  • The health of the host and environmental factors
    can change the balance of symbiotic relationships
  • Humans can manage environmental factors by the
    use of drugs and pesticides to help improve
    human, animal and plant health.
  • Herbicides are used in the management of plant
    competition

37
6. Survival Strategies
  • Regulators maintain their internal environment
    regardless of the external environment
  • regulators have homeostatic control
  • osmoregulators can maintain a stable internal
    water concentrations
  • homeotherms can maintain a stable internal
    temperate
  • Examples are mammals, insects birds
  • Conformers cannot maintain their internal
    environment
  • conformers do not have homeostatic control
  • osmoconformers are isotonic to their surroundings
  • poikilotherms internal temperature varies with
    the external environment
  • Examples are snakes, lizards and marine fish
  • Regulators can occupy a wide range of habitats
    due to homeostatic mechanisms but conformers have
    a restricted habitat occupation

38
Dormancy
  • Dormancy is a way that many organisms can resist
    or tolerate environmental conditions
  • Predictive dormancy occurs before the adverse
    conditions. It is triggered by environmental
    conditions e.g. decreasing temperature or
    photoperiod (and is largely under genetic
    control)
  • Consequential dormancy occurs immediately as a
    direct result of changing environmental
    conditions
  • Different forms of dormancy include- resting
    spores, diapause, hibernation aestivation

39
Types of Dormancy
  • Resting spores dormancy in seeds. A hard case
    surrounds the dehydrated seed or spore until
    conditions are beneficial (e.g. warmer
    temperatures)
  • Diapause dormancy in insects and deer. Insects
    wont develop until better conditions in spring
    and deer mate at a particular time so the young
    are born in spring.
  • Hibernation bears, squirrels. Inactivity time
    used to escape cold weather conditions and scarce
    food supplies
  • Aestivation inactivity time associated with
    hot, dry periods. Organism remains in a state of
    torpor with a reduced metabolic rate e.g. desert
    frogs lungfish

40
7. Succession
  • Ecological succession is the name given to a
    repeatable series of changes in the types of
    species which occupy a given area through time
    from a pioneer to a climax community
  • Autogenic Succession is the changes in
    environmental conditions which leads to changes
    in species composition in an ecosystem caused by
    the biological processes of the organisms
    themselves
  • 2 Types of Allogenic Succession are Primary
    Secondary Succession

41
Succession
42
Primary Secondary Succession
Primary succession occurs when plants become
established on land which has not previously been
inhabited and where no soil exists e.g. barren
rock Secondary succession occurs when plants
invade a habitat which was previously inhabited
by other plants and which therefore has existing
soil and some organic material present e.g. a
forest destroyed by fire Primary succession
takes longer than secondary succession because in
primary succession the soil has to be formed
43
Pioneer to Climax Communities
  • Pioneer species are first to colonise and can
    withstand difficult environmental conditions e.g.
    drying out (e.g. lichens)
  • Climax community is a relatively stable community
    in which no further succession takes place
  • During succession from a pioneer to a climax
    community all of the following increase-
  • - complexity
  • - species diversity
  • - habitat variety
  • - productivity
  • - food webs
  • - stability

44
Degradative Succession
  • Degradative succession (or Heterotrophic
    succession) is the sequence of changes associated
    with the decomposition process. For instance,
    when organisms die and begin to decompose, a
    characteristic sequence of certain species appear
    associated with that type of organism.
  • This chain can be used by Forensic entomologists
  • Dead Cow gt BacteriagtFlies lay eggs on bodygt
  • Larvae hatch feed on bodygt Beetles feed
  • lay eggsgtSpiders feed on insects

45
Loss of Complexity of Ecosystems
  • Loss of complexity can be brought about by
  • - monoculture
  • - eutrophication
  • - toxic pollution
  • - habitat destruction

46
8. Intensive Food Production
  • Monoculture is when a single species is grown
    over a large area
  • The aim of monoculture is to reduce the
    complexity of the ecosystem to a single species
    in order for the farmer to gain highest yields at
    minimal costs to get maximum profit
  • Population sizes throughout the world are
    increasing and we thus need more food
  • Hedgerows and fences are taken down to make large
    fields so machinery can plough them easily. This
    removes habitats and shelters and reduces
    organisms living there
  • A monoculture is not a climax community so it is
    unstable and is at risk from competition from
    other plant species. Therefore humans remove
    these additional plants by hand (organic farming)
    and by the use of herbicides.

47
Problems with Monoculture
  • Monocultures are highly unstable and are
    vulnerable to-
  • disease caused by bacteria, fungi and viruses
  • attacks from pests (weeds, insects and animals)
  • soil erosion
  • adverse weather conditions
  • The same crops are used year after year so the
    soil has the same nutrients taken from it
    consistently. Also, after harvesting, the field
    is cleared of plant debris (so nutrient cycles
    dont occur).
  • To increase the fertility of the soil fertilisers
    are used.
  • Organic fertilisers are manure and composts,
    whereas inorganic fertilisers are made from
    chemicals
  • Pesticides (kill pests) and Herbicides (reduce
    competition by weeds) also contain substances
    which are toxic to organisms other than those
    they are intended to kill
  • Industrial sites are often polluted with heavy
    metals such as lead, cadmium and mercury which
    can lead to the death of many organisms, leading
    to the decrease in complexity of ecosystems

48
Eutrophication
  • Waterways near the fields can become polluted by
    excess nutrients e.g. by adding untreated sewage,
    runoff of animal waste from farms, leaching of
    fertilisers from fields
  • This pollution increases the nitrates and
    phosphates in the water system
  • The increase in nutrients leads to an explosion
    of algal growth (algal blooms).
  • Algal blooms increase oxygen levels in the day by
    photosynthesis, but oxygen depletion occurs at
    night due to respiration
  • Algae die and accumulate at bottom of water
    system, and decomposers feed on them, which
    decreases the oxygen levels even further, so
    water plants and larger animals die due to lack
    of oxygen. Eventually species diversity in the
    water is drastically reduced

49
Eutrophication
Loch Eutrophication
Coastline Eutrophication
50
9. Increase in Energy Needs
  • An increase in the human population as resulted
    in an increase in our energy needs
  • Fossil Fuels (coal, oil and gas) are finite and
    will soon
  • run out if we continue to use them at the
    present rate

51
Alternative Energy Sources
  • We need to conserve fossil fuels and use
    alternative sources of energy such as-
  • Nuclear
  • Solar
  • Wind
  • Hydro-electric
  • Wave
  • Tidal
  • Geothermal
  • Biofuels

52
Air Pollution Greenhouse Gases
  • When Fossil fuels are burned they release acidic
    gases which cause air pollution
  • sulphur dioxide
  • nitrous oxide
  • carbon dioxide
  • Fossil fuels also release greenhouse gases-
  • carbon dioxide
  • water
  • methane
  • nitrous oxide
  • CFCs

53
Greenhouse Effect
  • Solar energy passes through the atmosphere
    striking the earths surface and thus warms it
    up, producing infrared radiation (heat). Most of
    this radiation is reflected back to space but
    some greenhouse gases absorb some of this heat,
    making the earth warmer this is called the
    greenhouse effect.
  • Called the greenhouse effect because in a real
    greenhouse, glass acts as the atmosphere and
    traps some of the heat energy.
  • When too much heat is absorbed by greenhouse
    gases, global warming may occur

54
Greenhouse Effect
  • Illustration 1 The earth is covered by a blanket
    of gases which allow light energy from the sun to
    reach the earth's surface, where it is converted
    to heat energy. Most of the heat escapes our
    atmosphere, but some is trapped. This natural
    effect keeps the earth warm enough to sustain
    life. Illustration 2 Human activity such as
    burning fossil fuels (coal, oil and natural gas)
    and land clearing is creating more greenhouse
    gases. This traps more heat, so the earth becomes
    hotter.

55
Global Warming
  • Global warming may cause climate change (e.g.
    changes in temperature, rainfall levels, sea
    levels) which could affect the distribution of
    many different species
  • Scientists predict that climate change will
    happen too fast for organisms to adapt or move so
    it could result in a decrease in species
    diversity

56
Global Warming Effects on Animals
  • Increased storms damaging the breeding colonies
    of albatross, already facing heavy pressure from
    accidental capture on long-line fishing hooks
  • Sea level rise destroying beach nesting sites for
    sea turtles
  • Seals and wading birds also face destruction of
    their coastal habitats
  • Warmer seas could lead to some turtle species
    becoming entirely female, as water temperature
    strongly affects the sex ratio of hatchlings
  • The spreading extent of the Sahara desert could
    threaten long-range travellers such as the
    swallow, as they will be unable to "fuel up" in
    previously fertile regions on the desert's edge.

57
Coral Bleaching
  • Coral Bleaching is an example of how global
    warming might affect the distribution and
    diversity of different species.
  • Colourful Coral reefs are made up of a symbiotic
    relationships of coral polyps (which secret a
    skeleton of white calcium carbonate) and a
    unicellular-coloured algae called zooanthellae.
  • Zooanthellae provides the coral polyps with
    nutrients produced from photosynthesis and the
    coral polyps provide the zooanthellae with a
    protected environment and lots of carbon dioxide
    for photosynthesis a mutualistic relationship
  • Temperature increase causes the algae
    zooanthellae to leave the coral, leaving just the
    white skeleton thus called coral bleaching
  • If temperature increase is reversed zooanthellae
    may repopulate the reef and the coral may
    recover, of not the coral polyps eventually die.

58
Coral Bleaching
Sun Coral in ideal temperatures
Coral bleaching in process
59
10. Pollution
  • Pollution is the negative effect of a harmful
    substance on the environment
  • Pollution may cause the following biological
    effects-
  • the appearance of a species
  • the disappearance of a species
  • changes in community structure and function
  • changes in behaviour
  • changes in productivity, energy flow and nutrient
    cycling
  • The 4 ecosystems that can be effected by
    pollution are-
  • sea (oil spills, dumping of radioactive waste,
    dumping of toxic waste)
  • air (emissions from cars, planes, industry)
  • land (landfill sites, domestic rubbish)
  • freshwater (agricultural run off, organic sewage)

60
Measuring Pollution
  • Freshwater can be polluted by organic material by
    the dumping of untreated sewage
  • This organic sewage provides a rich food source
    for microorganisms that feed, reproduce and use
    up the oxygen in the water. Other organisms such
    as fish die.
  • Biodegradable organic pollutants include sewage,
    farm waste and industrial waste
  • Ecosystems need continually monitoring to ensure
    they are free from harmful levels of pollutants.
    Water can be tested directly or indirectly.
  • Direct methods of water testing are-
  • Colour
  • Turbidity
  • Dissolved Oxygen levels
  • PH
  • Biochemical Oxygen Demand (BOD)
  • Odour
  • Temperature
  • Ammonia, nitrate, chloride, phosphorus levels

61
BOD Testing
  • The BOD (Biochemical Oxygen Demand) test is a
    water quality test that measures the levels of
    dissolved oxygen in the water. It is used to
    estimate the levels of biodegradable organic
    material there is.
  • High BOD levels indicate a high level of organic
    pollution in the water, and a low BOD level
    indicates a low level of organic pollution in the
    water
  • BOD Test 2 samples of water are taken from the
    same site. Sample 1 is tested immediately, and
    Sample 2 is incubated for 5 days in the dark at
    20C and then the BOD is taken.
  • The difference in dissolved oxygen content of the
    2 samples shows the amount of oxygen consumed by
    microbial respiration as bacteria break down the
    organic matter in the sample.

62
Biological Monitoring
  • Indicator species give information about the
    environment that it is living in
  • Biological Monitoring is an indirect measure of
    water quality
  • A susceptible species can be used as an indicator
    species, as their disappearance from a habitat
    that they were in previously indicates that the
    environmental conditions have changed. For
    example, lichens disappearing indicates increased
    levels of sulphur dioxide
  • A favoured species can tolerate a wide range of
    environmental conditions, so cannot be used as an
    indicator species

63
Chemical Transformations
  • Once chemicals have been released into the
    environment, their chemical nature changes due to
    their interactions with each other and the
    environment, this is called CHEMICAL
    TRANSFORMATION
  • Sometimes chemical transformations can turn
    relatively safe chemicals into toxic ones
  • Biotransformation of the heavy metal mercury by
    Clostridium, Neurospora and Pseudomonas. These
    organisms can all methylate metallic mercury
    changing it from a moderately toxic chemical into
    a highly toxic one that change damage kidney,
    liver and brain tissue in humans
  • When a chemical accumulates in the tissues of an
    organism it is called BIOACCUMULATION
  • BIOMAGNIFICATION is when some toxins become very
    harmful because they become more concentrated in
    successive trophic levels of a food web. This is
    due to the fact that some chemicals (e.g.
    chlorinated hydrocarbons) accumulate in specific
    tissues, especially fat.

64
DDT
  • DDT (Dichlorodiphenyltrichloroethane) is an
    insecticide that was commonly used during the
    1940s 1950s. It was used to kill insects like
    mosquitoes that carried malaria and saved many
    lives.
  • DDT is no longer used due to its long-term lethal
    side effects.
  • DDT bioaccumulates in the body fats of organisms.
  • DDT is biomagnified through the food chain, so at
    each tropic level the concentration of DDT
    increases
  • DDT breaks down to form a stable compound called
    DDE which thins the shells of many birds reducing
    the survival rate of many birds (e.g. osprey)
  • Large scale resistance to DDT has evolved with 35
    species of malarial mosquitoes now resistant
  • Areas of the world that did not use DDT show high
    levels of the chemical. Inuit people from
    Greenland have high levels of DDT in the tissues
    acquired from consuming seals that had visited
    DDT regions
About PowerShow.com