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 Advanced Higher

Biology

Environmental Biology Unit

 Anderson High School

CR

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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

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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)

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Environmental Biology

10 Topics 1 Energy Fixation

2 Circulation of Nutrients

3 Biotic Interactions

4 Symbiotic Relationships5 Costs/Benefits of Competition

6 Survival Strategies

7 Succession

8 Intensive Food Production9 Increase in Energy Needs

10 Pollution

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1. Energy Fixation

Energy is required by all organisms forcellular activities, growth &reproduction

The fixation of energy occurs inphotosynthesis by autotrophs

 Autotrophs (are producers) thatchange light energy into chemicalenergy to make organic molecules

Heterotrophs (are consumers) thatmust feed on other plants or animalsto get a ready made supply of organic

molecules

Saprotrophs (are decomposers) thatuse the organic materials from wasteand dead organisms as an energysource 

 Autotrophs

Heterotrophs

Saprotrophs

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Energy Calculations

Gross Primary Productivity (GPP) is the total amount oflight energy converted to chemical energy by autotrophs

Not all energy produced by autotrophs is available forconsumers 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  

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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 secretingdigestive enzymes

Detritivores are organisms (e.g. earthworms & woodlice) thatfeed on detritus (decomposing material)

Primary consumers are herbivores that feed directly onproducers

Secondary consumers are carnivores that feed on primaryconsumers

Tertiary consumers are carnivores that feed on secondaryconsumers

 A trophic level is a feeding level present in a food chain or foodweb

Energy flow in a food chain or food web is represented byarrows

Energy transfer is not very efficient. Only 10% of energy at one

trophic level is passed on to the next level

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Biological Pyramids

Pyramids of numbers represent the number oforganisms at each trophic level

Pyramids of biomass represent the mass oforganisms at each trophic level

Pyramids of productivity represent the energyavailable at each trophic level

In an ecosystem, productivity, biomass andnumbers of organisms tend to decrease at eachtrophic level

The ultimate loss of energy is in the form of HEAT(from respiration)

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2. Circulation of Nutrients

Decomposition is the breakdown of organic matterwith the release of inorganic nutrients into thesurrounding soil

Inorganic ions are released from decomposingmatter in a process called mineralisation

Decomposers and Detritivores are involved indecomposing organic matter

Undecomposed material is called litter

Completely decomposed matter is called humus

Invertebrate detritivores (e.g. worms) increase thedecomposition rate as they reduce the particle sizeof the detritus, making it easier for the decomposers(bacteria & fungi) to break down detritus to formhumus

Decomposers are the ultimate releasers of energyand carbon dioxide fixed in photosynthesis

Nutrients must be recycled for the primaryproducers to use 

Detritivores (e.g. worms)

Decomposers (e.g. wood fungi)

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Nitrogen CycleThere 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 convertsatmospheric nitrogen to ammonia with the use of ATP

The plant (legume) and the Rhizobium bacteria produce a molecule called Legheamoglobin. This moleculebinds 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 

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The Nitrogen Cycle

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The Nitrogen Cycle (again)

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Nitrogen Cycle 

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Nitrogen Fixation Fixation is when Atmospheric Nitrogen is

converted to Ammonia

Free living cyanobacteria in the soil fixnitrogen

Rhizobium bacteria in the root nodules oflegumes fix nitrogen

Cyanobacteria & Rhizobium bacteria have anenzyme complex called nitrogenise whichconverts atmospheric nitrogen to ammoniawith the use of ATP

The plant (legume) and the Rhizobiumbacteria produce a molecule calledLegheamoglobin. This molecule binds withoxygen which is really important as nitrogenfixation is an anaerobic process

Cyanobacteria

Rhizobium

Root Nodules Clover

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Nitrification

Nitrification is when Ammonium is converted toNitrites then to Nitrates

Nitrosomonas and Nitrobacter

bacteria carry out this process

The nitrates are then used byplants to make proteins &nucleic acids (assimilation)

Nitrates can be lost byleaching and denitrifyingbacteria (Pseudomonas) 

Nitrification

 Ammonium

Nitrites

Nitrates

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Denitrification

Denitrification is when Nitrates are

converted back to Atmospheric Nitrogen

Denitrifying bacteria (Agrobacterium) are

involved

Nitrates  Atmospheric Nitrogen Agrobacteria

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Ammonification

 Ammonification is when organic nitrogen in

Proteins is converted into ammonia by

decomposers (bacteria & fungi)

Nitrogen Ammonia

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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

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Phosphorus Cycle

Phosphorus Cycle

Phosphorus is added to the soil by the weathering of rocks, taken upby primary producers and returned by decomposition

Phosphorus is a main component of nucleic acids, phospholipids, ATP, bones, teeth

Phosphorus is organic, doesn’t have a gaseous form, so the onlyinorganic form is phosphate

Phosphate is a limiting factor in the productivity of aquaticecosystems

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 inthe water, so fish and other organisms eventually die 

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Phosphorus Cycle

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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 apopulation. These factors increase as population size increasese.g. predation, disease, food supply, competition

Density independent factors are factors that can regulate apopulation. These factors are independent of population size e.g.hurricanes, forest fires

Interspecific Competition is interactions betweenindividuals of different species

Intraspecific Competition is interactions betweenindividuals of the same species and is more intense that

Interspecific Competition

Predator/Prey interactions are cyclical, but slightly outof phase with each other due to the changes in predator numberslagging behind those of the prey (e.g. Lynx – Snowshoe Hare)

Predators have a role in maintaining species diversity inecosystems by controlling the numbers of more dominantcompetitors in an ecosystem, thus allowing weaker competitors tosurvive

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Defence Against Predation

3 Main Defences:-

1. Camouflage Camouflage is when the organisms colouring or patternallows it to merge into the background

a) Crypsis – hiding to reduce the risk of predation

b) Disruptive Colouration – patterns on body don’t matchoutline

2. Warning Colouration Warning Colouration is when organisms are brightlycoloured to warn predators that they are dangerous to eat

3. Mimicry Mimicry is when an organism bears a resemblance to aharmful speciesa) 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 tohave the same or similar warning signals 

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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 don’t match outline (e.g.zebra)

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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

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Mimicry

Mimicry is when an organism

bears a resemblance to a harmful

speciesa) Batesian mimicry is when an

edible or harmless speciesmimics a poisonous or

harmful species (e.g. harmlessrobber fly has similarcolourings to a wasp)

b) Mullerian mimicry is when 2 ormore species have evolved to

have the same orsimilar warning signals (e.g.social wasps and caterpillarsof cinnabar wasps) 

Harmless Robber fly Harmful wasp

 Wasp Cinnabar

Caterpillar

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Grazing

 A grazer is defined as any

species that moves from one

 victim to another, feeding on a

part of each victim but

doesn’t actually kill it 

Moderate grazing can increase

the biodiversity of species

present as grazing reduces the

number of dominant grassesand other plants with basal

meristems, which allows weaker

competitors to survive 

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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.

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Niche

For A’Higher 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

one species will dominate and the other

species will move away 

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Resource Partitioning

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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 effectssoil ecosystems

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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 anutritional advantage 

Examples of Symbiosis are

Parasitism, Commensalism, and Mutulaism

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Parasitism

Parasitism is a biotic interaction which isbeneficial to one species (the parasite)and detrimental to the other species (thehost) e.g. tapeworm and humans

 An obligate parasite cannot survivewithout the host organism

 A facultative parasite can live with orwithout the host

Endoparasites live within a hosts bodye.g. tapeworms, liver flukes, malarialparasites

Ectoparasites live on the surface of thehost e.g. ticks, fleas, leeches

Ectoparasite –  Dog Tick

Endoparasite –  human tape

 worm

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Host-Parasite Balance

 A balance exists between the parasite and the host sothat 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 malarialparasite

Host-parasite specificity gives evidence of evolutionaryadaptation e.g. immunity 

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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 scrapsof dead prey of sea

anemone

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Mutualism

Mutualism is a biotic

interaction beneficial to

both species.

The anemone is taken to

new habitats when thecrab moves so the crab

gets to new food sources

The crab gains protection

from predators from theanemones stinging cells

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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 useof drugs and pesticides to help improve human, animal

and plant health. Herbicides are used in the management of plant

competition

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6. Survival Strategies

Regulators maintain their internal environmentregardless of the external environment regulators have homeostatic control

osmoregulators can maintain a stable internal waterconcentrations

homeotherms can maintain a stable internaltemperate

Examples are mammals, insects & birds

Conformers cannot maintain their internalenvironment conformers do not have homeostatic control

osmoconformers are isotonic to their surroundings

poikilotherms internal temperature varies with theexternal environment

Examples are snakes, lizards and marine fish

Regulators can occupy a wide range of habitatsdue to homeostatic mechanisms but conformershave a restricted habitat occupation

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Dormancy

Dormancy is a way that many organisms can resist ortolerate environmental conditions

Predictive dormancy occurs before the adverseconditions. It is triggered by environmental conditionse.g. decreasing temperature or photoperiod (and islargely under genetic control)

Consequential dormancy occurs immediately as a directresult of changing environmental conditions

Different forms of dormancy include:- resting spores,diapause, hibernation & aestivation

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Types of Dormancy

Resting spores – dormancy inseeds. A hard case surrounds thedehydrated seed or spore untilconditions are beneficial (e.g.warmer temperatures)

Diapause – dormancy in insectsand deer. Insects won’t developuntil better conditions in springand deer mate at a particular timeso the young are born in spring.

Hibernation – bears, squirrels.Inactivity time used to escape coldweather conditions and scarcefood supplies

 Aestivation – inactivity timeassociated with hot, dry periods.Organism remains in a state oftorpor with a reduced metabolicrate e.g. desert frogs & lungfish

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7. Succession

Ecological succession is the name given to a repeatableseries of changes in the types of species which occupy agiven area through time from a pioneer to a climaxcommunity

 Autogenic Succession is the changes in environmentalconditions which leads to changes in speciescomposition in an ecosystem caused by the biologicalprocesses of the organisms themselves

2 Types of Allogenic Succession are – Primary &Secondary Succession

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Succession

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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 primarysuccession the soil has to be formed 

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Pioneer to Climax Communities

Pioneer species are first to colonise and can withstanddifficult environmental conditions e.g. drying out (e.g.lichens)

Climax community is a relatively stable community inwhich no further succession takes place

During succession from a pioneer to a climax communityall of the following increase:-

- complexity

- species diversity

- habitat variety- productivity

- food webs

- stability

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Degradative Succession

Degradative succession (or Heterotrophicsuccession) is the sequence of changesassociated with the decomposition process. Forinstance, when organisms die and begin to

decompose, a characteristic sequence of certainspecies appear associated with that type oforganism.

This chain can be used by Forensic

entomologists Dead Cow > Bacteria>Flies lay eggs on body>

Larvae hatch & feed on body> Beetles feed &

lay eggs>Spiders feed on insects

f C f

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Loss of Complexity of

Ecosystems

Loss of complexity can be brought about

by:

- monoculture

- eutrophication

- toxic pollution

- habitat destruction 

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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 atminimal costs to get maximum profit

Population sizes throughout the world are increasing and we thusneed more food

Hedgerows and fences are taken down to make large fields somachinery can plough them easily. This removes habitats andshelters and reduces organisms living there

 A monoculture is not a climax community so it is unstable and is atrisk from competition from other plant species. Therefore humansremove these additional plants by hand (organic farming) and by the

use of herbicides. 

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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 plantdebris (so nutrient cycles don’t occur). 

To increase the fertility of the soil fertilisers are used.

Organic fertilisers are manure and composts, whereas inorganic fertilisersare made from chemicals

Pesticides (kill pests) and Herbicides (reduce competition by weeds) alsocontain 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 thedecrease in complexity of ecosystems

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Eutrophication

Waterways near the fields can becomepolluted by excess nutrients e.g. byadding untreated sewage, runoff ofanimal waste from farms, leaching offertilisers from fields

This pollution increases the nitratesand phosphates in the water system

The increase in nutrients leads to anexplosion of algal growth (algalblooms).

 Algal blooms increase oxygen levels inthe day by photosynthesis, but oxygendepletion occurs at night due torespiration

 Algae die and accumulate at bottom of

water system, and decomposers feedon them, which decreases the oxygenlevels even further, so water plantsand larger animals die due to lack ofoxygen. Eventually species diversity inthe water is drastically reduced

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Eutrophication

Coastline Eutrophication

Loch Eutrophication

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9. Increase in Energy Needs

 An increase in the human population as resulted in anincrease 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

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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 

Ai P ll ti & G h

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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

methanenitrous oxide

CFC’s 

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Greenhouse Effect

Solar energy passes through theatmosphere striking the earth’ssurface and thus warms it up,producing infrared radiation (heat).Most of this radiation is reflectedback to space but somegreenhouse gases absorb some of

this heat, making the earth warmer – this is called the greenhouseeffect.

Called the greenhouse effectbecause in a real greenhouse, glassacts as the atmosphere and traps

some of the heat energy.

When too much heat is absorbed bygreenhouse gases, global warmingmay occur  

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Greenhouse Effect

Illustration 1 The earth is covered by a blanket of gases which allow light energy from the sun to reachthe earth's surface, where it is converted to heat energy. Most of the heat escapes ouratmosphere, but some is trapped. This natural effect keeps the earth warm enough tosustain life.

Illustration 2 Human activity such as burning fossil fuels (coal, oil and natural gas) and land clearing iscreating more greenhouse gases. This traps more heat, so the earth becomes hotter.

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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 speciesdiversity

Gl b l W i Eff t

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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 coastalhabitats

 Warmer seas could lead to some turtle species becoming entirelyfemale, as water temperature strongly affects the sex ratio ofhatchlings

 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.

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Coral Bleaching

“Coral Bleaching” is an example of how global warming might affect thedistribution and diversity of different species.

Colourful Coral reefs are made up of a symbiotic relationships of coralpolyps (which secret a skeleton of white calcium carbonate) and aunicellular-coloured algae called zooanthellae.

Zooanthellae provides the coral polyps with nutrients produced fromphotosynthesis and the coral polyps provide the zooanthellae with aprotected environment and lots of carbon dioxide for photosynthesis – amutualistic 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 reefand the coral may recover, of not the coral polyps eventually die. 

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Coral Bleaching

Sun Coral in ideal temperatures Coral bleaching in process

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10. Pollution

Pollution is the negative effect of a harmful substance on theenvironment

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)

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Measuring Pollution

Freshwater can be polluted by organic material by the dumping of untreatedsewage

This organic sewage provides a rich food source for microorganisms thatfeed, reproduce and use up the oxygen in the water. Other organisms suchas fish die.

Biodegradable organic pollutants include sewage, farm waste and industrialwaste

Ecosystems need continually monitoring to ensure they are free fromharmful 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

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BOD Testing

 The BOD (Biochemical Oxygen Demand) test is a water quality test thatmeasures the levels of dissolved oxygen in the water. It is used to estimate thelevels 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 istested immediately, and Sample 2 is incubated for 5 days in the dark at 20°Cand then the BOD is taken.

 The difference in dissolved oxygen content of the 2 samples shows theamount of oxygen consumed by microbial respiration as bacteria break downthe organic matter in the sample. 

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Biological Monitoring

Indicator species give information about the environmentthat it is living in

Biological Monitoring is an indirect measure of waterquality

 A susceptible species can be used as an indicator species,as their disappearance from a habitat that they were inpreviously indicates that the environmental conditionshave changed. For example, lichens disappearing indicatesincreased levels of sulphur dioxide

 A favoured species can tolerate a wide range ofenvironmental conditions, so cannot be used as anindicator species 

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Chemical Transformations

Once chemicals have been released into the environment, their chemical nature changes due totheir 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 chemicalinto 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 calledBIOACCUMULATION

BIOMAGNIFICATION is when some toxins become very harmful because theybecome more concentrated in successive trophic levels of a food web. This is due to the fact thatsome chemicals (e.g. chlorinated hydrocarbons) accumulate in specific tissues, especially fat.

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DDT

DDT (Dichlorodiphenyltrichloroethane) is an insecticide that was commonly usedduring the 1940’s & 1950’s. It was used to kill insects like mosquitoes that carriedmalaria 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 malarialmosquitoes now resistant

 Areas of the world that did not use DDT show high levels of the chemical. Inuitpeople from Greenland have high levels of DDT in the tissues acquired fromconsuming seals that had visited DDT regions