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The Biosphere

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The biosphere is the zone of life around Earth, from the deepest ocean to high ... Badly polluted water bloodworm, water louse ... – PowerPoint PPT presentation

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Title: The Biosphere


1
The Biosphere
  • Revision

2
Sub-topic (a)
  • Investigating an Ecosystem

3
What is the biosphere?
  • The biosphere is the zone of life around Earth,
    from the deepest ocean to high in the atmosphere
  • Within the biosphere there are numerous
    ecosystems which are natural biological areas
    such as woodlands, ponds, hillsides, rivers etc

4
Ecosystems are usually very large and complex
  • Ecosystems are made up of animal and plant
    communities plus habitats
  • Living factors in the ecosystem are called BIOTIC
    factors
  • Non living factors are called ABIOTIC factors

5
Sampling
  • Because ecosystems are usually large and complex
    It is impossible to count every organism and
    habitat in the ecosystem
  • We therefore have to sample the ecosystem to
    identify numbers

6
Sampling Biotic factors
  • A quadrat is used to sample Plants or slow moving
    animals
  • It is thrown at RANDOM on the area of ground
    being sampled. This is step is repeated several
    times
  • The number of squares which contain an identified
    plant are counted

0.5m
0.5m
7
Measuring Abundance
  • Abundance is a measure of how rare or common a
    plant type is

grass
dandelion
pansy
Only the squares that contain a particular plant
are counted NOT the total number of
plants Calculate the abundance ratio for each of
the plants shown
8
Errors during quadrat sampling
  • Errors or mistakes must be kept to a minimum to
    ensure results from sampling are reliable
  • Quadrats must be thrown at random
  • If the sample area is large it must also be
    thrown numerous times to give a accurate
    representation of the area

9
Sampling Biotic factors continued
  • A pitfall trap is used to obtain samples of small
    animals that move along the grounds surface
  • The stones prop up the lid of the trap which
    could be leaves/wood etc
  • The lid prevents flooding and camouflages the trap

bait
10
Measuring Abiotic Factors
  • Light and moisture are 2 easily measured abiotic
    factors
  • To measure light intensity we use a light meter
  • To measure moisture we use a moisture meter

11
Measuring light and moisture
  • The moisture meter probe is carefully pushed into
    the ground being careful not to hit any stones
  • A light meter is held at the soil surface and
    pointed in the direction of maximum light and the
    reading taken
  • Both meters are not very accurate they are only
    used for comparing readings

12
Possible sources of error
  • Care must be taken not to shade light with your
    body when taking a reading
  • Readings must also be taken at the same time of
    day under similar conditions
  • The probes of the moisture meters must be pushed
    into the same depth at each site
  • The probe must be cleaned/dried between samples

13
Errors made with pitfall traps
  • The top of the trap must be LEVEL with the ground
  • The soil rod about the trap should remain as
    undisturbed as possible
  • Traps should be checked often
  • The traps should have adequate drainage

14
Sub-topic (b)
  • How it Works

15
How ecosystems work
  • There are certain words you must know the
    definitions of
  • An ecosystem
  • Community Habitat

16
Food Chains
  • A food chain shows the feeding relationship
    between organisms within an ecosystem
  • The arrows show the direction of energy flow

Producer
Consumers
17
Food webs
  • A food web is a number of food chains that
    interconnect
  • When an organism is removed from the web, this
    has a knock on effect on other organisms in the
    web

18
Energy Loss
  • Not all energy conserved inside an organism is
    passed onto the next when it is eaten
  • Energy is lost from a food chain/web by movement
    and heat
  • Because an organism only converts a small amount
    of food into making new cells, there are usually
    fewer organisms at each stage in a food chain
  • This can be represented in a pyramid of numbers

19
Pyramid of numbers
Least numbers
Fewer numbers
Greatest number of organisms
  • This diagram shows the NUMBER of organisms
    present at each stage in a food chain

20
Are Pyramids of numbers reliable?
  • With PONs you can get odd results if organisms
    are really big or really small
  • A better way of representing food chains are
    PYRAMIDS OF BIOMASS

21
Pyramids of Biomass
  • Pyramids of biomass show the amount of biological
    material at each stage in a food chain.
  • Pyramids of biomass are always pyramid shaped

Least Mass
Greatest Mass
22
Factors that affect population growth
  • The no. of organisms in a population depends on
    the BIRTH rate and DEATH rate
  • Populations are limited due to several factors
    such as
  • Space
  • Food/water supply
  • Disease
  • predators

23
A typical growth curve
  • 1st stage shows little growth as there arent a
    lot of organism to reproduce
  • 2nd stage shows a rapid increase in numbers de to
    plentiful food and few predators
  • 3rd stage shows growth slowing due to food being
    used up and other growth limiting factors

3
2
1
24
Competition
  • Competition occurs when 2 organism need the same
    resource
  • Competition can be for
  • Space
  • Mates
  • Food
  • Light
  • Usually the strongest and fittest survive and the
    weakest organism will eventually become extinct
    in the ecosystem

25
The recycling of resources
  • Some resources are in short supply for all
    organisms such as carbon and nitrogen
  • Nitrogen makes up about 80 of out air but it is
    unreactive in this form
  • Special types of bacteria can fix nitrogen into
    useful nitrates
  • The recycling of nitrogen can be illustrated in
    the Nitrogen Cycle

26
N-Cycle simplified(!!!)
  • Plants can absorb nitrates through their roots to
    make protein.
  • Animals eating the plants can convert this
    protein into their own protein.
  • When protein is excreted or the animals die
    decomposers change the protein into ammonia in
    the soil.
  • Soil bacteria convert the ammonia into nitrites
    in the soil.
  • Soil bacteria convert the ammonia into nitrates
    in the soil.

27
Nitrogen fixing bacteria
  • Some plants have nitrogen fixing bacteria living
    in root nodules (swellings on the roots)
  • These bacteria can convert N gas from the air and
    convert it to forms that a plant can use such as
    nitrate
  • Other bacteria called DENITRIFYING bacteria can
    change soil nitrates into nitrogen gas (the
    opposite process from above)

28
The Nitrogen Cycle in all its glory!!
29
Sub-Topic (c)
  • Control and Management

30
What is pollution?
  • Pollution is the contamination of our
    surroundings by substances which harm living
    things
  • Often pollution cause disease and in extreme
    cases death
  • Pollution affects 4 main ecosystems AIR, LAND,
    FRESH WATER and the SEA

31
Sources of pollution
  • Domestic pollution such as raw sewage (faeces),
    household rubbish and old car parts

32
Sources of pollution
  • Agricultural pollution caused by excess use of
    fertilisers and pesticides
  • Excess liquids run off into rivers and streams
    affecting aquatic life.

33
Sources of pollution
  • Industrial pollution caused by the burning of
    fossil fuels, inorganic chemical wastes and
    nuclear power stations

34
Burning of Fossil Fuels
  • Poisonous gases such as carbon monoxide, nitrogen
    oxides and sulphur dioxide are produced
  • These gases react with light, water and oxygen in
    the atmosphere to form acid rain
  • Acid rain falls and affects trees at high
    altitudes by causing yellowing of leaves/needles
    or even death
  • Acid rain also interacts with soil leading to it
    being run off into water causing the death of
    aquatic animals that cannot withstand acidic
    waters

35
Nuclear Power
  • Nuclear power is used in some power stations
    instead of fossil fuels to make electricity
  • Radioactive waste is produced from this which
    give out harmful radiation for many years to come
  • Radiation can cause diseases such as leukemia and
    other forms of cancer

36
Controlling pollution
  • Domestic recycling and alternative methods of
    disposal, lead free petrol, catalytic converters
    in cars
  • Agricultural use minimum concs of fertilisers
    or pesticides
  • Industrial scrubbers in chimney which removes
    SO2 from gases, sealing of radioactive waste in
    lead containers and dumping on ocean bed,
    alternative energy sources (sun, wind waves etc)

37
Organic Waste
  • Organic waste is the unwanted remains of living
    things such as sewage, dead leaves and stale food
  • Organic waste is and ideal food source for
    decomposing micro-organisms that bring about
    decay
  • Sewage is usually treated at sewage works by
    being fed to these micro organisms which break it
    down into harmless substances

38
River Pollution
  • Some sewage can end up untreated in rivers and
    waterways
  • Because they provide a food source for
    micro-organisms, when they feed on it they
    rapidly multiply and use up the rivers supply of
    dissolved oxygen
  • This oxygen shortage leads to the death of
    aquatic organisms

39
Organisms found in polluted rivers
  • Clean water - mayfly nymph, stonefly nymph
  • Partly polluted water freshwater shrimp, caddis
    fly larva
  • Badly polluted water bloodworm, water louse
  • Very badly polluted water sludge worm, rat
    tailed maggot

40
Indicator species
  • These are organisms which only thrive well under
    certain environmental conditions such as the
    organisms discussed
  • Trout need oxygen rich water whereas roach are
    more tolerant of lower O2 concentration
  • Different types of lichen differ in their
    sensitivity to sulphur dioxide gas

41
Poor management
  • Example overuse of fertilsers and pesticides
  • Effect excess chemicals are washed into rivers
    and lakes by the rain. They are difficult to
    decompose so end up in the food chain
  • Solution use minimum fertilisers on land near
    waterways. Develop biodegradable pesticides

42
Poor Management
  • Example overgrazing of grassland
  • Effect overgrazed plants die and so no longer
    retain water in the soil so the area becomes
    desert like. People become poorer and more prone
    to disease and malnutrition
  • Solution crop rotation, develop irrigation
    schemes
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