Abiotic and Biotic.pdf

*Difference between biotic and abiotic
*Levels of Ecological Organization
*Abiotic Factors affecting the abundance and distribution of organisms

1. Ecology: Lesson 1
Abiotic and Biotic Factors

2. Read the descriptions below and choose the correct keyword being described.
1.All the organisms of a single species living in a habitat.
2.The populations of different species living in a habitat.
3.The non-living factors of an environment.
4.The living factors of an environment.
5.The interaction between the living organisms and the different factors
of the environment.
Starter Task Answers
Population
Community
Abiotic
Biotic
Ecosystem
Abiotic factors can include the following: moisture, light, temperature,
CO
2, wind, O
2or soil pH.
Biotic factors can include the following: predators, competition,
pathogens, availability of food.
abiotic biotic community ecosystem population

3. Key Terms
Species consisting of similar individuals capable of exchanging
genes or interbreeding to produce fertile offspring.
All the organisms of a species living together in a habitat are
called a population.
The different populations which live together in a habitat are
called a community.
The living things and their interactions with the environment
they live in is called an ecosystem.
An individual, living thing is called an organism.

4. Levels of Ecological Organization

5. Abiotic factors affecting the abundance &
distribution of organisms
Light
Someplantshaveevolvedforoptimumgrowthinbright
sunlight.Anexampleofthisisacactushouseplant.Cacti
originallycomefromdesertswheretheygrowinbright
sunlight.Otherplantshaveevolvedtogrowinshade.
Manyorchids,whicharealsokeptashouseplants,grow
ontreesintherainforestandhaveevolvedforoptimum
growthindarkerconditions.Ifyouweretoputanorchid
onabrightwindowsillandacactusinadarkcornerof
yourroomneitherplantwouldgrowwell.

6. Abiotic factors affecting the abundance &
distribution of organisms
Temperature
Bothanimalsandplantshaveevolvedtogrowhealthily
attheiroptimumtemperatures.Ifyouplantedeither
yourcactusororchidhouseplantsoutsideincold
temperatures,theywoulddie.Similarly,animalsthat
haveevolvedtoliveattheNorthPole,suchasthepolar
bear,couldnotsurviveinwarmerconditions.

7. Abiotic factors affecting the abundance &
distribution of organisms
Moisture levels
Morepeoplekillhouseplantsbyoverwateringthanby
under-wateringthem.Manyplantscannotsurvivein
waterloggedsoils.Theirrootsareunabletorespire,they
rotandtheplantdies.Otherplants,suchaspitcher
plants,growbestinbogswherethemoisturelevelsare
high.Soilmoisturemeterscanaccuratelydeterminehow
wetanareais.

8. Abiotic factors affecting the abundance &
distribution of organisms
Soil pH content
ThepHofsoilscanhaveahugeeffectontheplantsthat
areabletogrowinthem.Someplants,likeazaleas,grow
bestinacidicsoilsandwillquicklydieifplantedin
alkalinesoils.Others,likeclematis,preferalkalinesoils.
Some,likethehydrangea,cangrowinboth.Theseplants
areunusualinthattheirflowercolourchangesin
differentsoils.Justlikeuniversalindicatorpaper,
hydrangeaflowersarepinkinacidicsoilsandbluein
alkalinesoils.

10. Abiotic factors affecting the abundance &
distribution of organisms
Soil mineral content/Substrate
Many plants require high levels of soil minerals to grow
well. An example of this is magnesium, which is required
to produce chlorophyll. Plants with unnaturally yellow
leaves may have a magnesiumdeficiency. Carnivorous
plants, such as pitcher plants, have evolved to catch
insects to supplement the low levels of minerals found in
the soils in which they grow.

12. Abiotic factors affecting the abundance &
distribution of organisms
Carbon dioxide
Carbon dioxide is a reactant inphotosynthesiswhich
means plants need it to survive. Areas with higher levels
of carbon dioxide are more likely to have healthy plants
growing. Farmers often release carbon dioxide within
their greenhouses to maximize theircrop yield.
Woodlands often have higher carbon dioxide levels than
open grassland, so many plants living in open areas have
evolved mechanisms to overcome a shortage of carbon
dioxide.

13. Abiotic factors affecting the abundance &
distribution of organisms
Oxygen levels for aquatic animals
Oxygenfromtheairandoxygenproducedbyaquatic
plantsdissolvesinwater.Withoutthis,aquaticanimals
wouldsuffocateanddie.Healthylakesandrivershave
highlevelsofoxygen,andpollutedwatersoftenhavelow
levelsofoxygen.Thispollutionmeansthatonly
certainspeciescansurvivetheresuchassludgeworms.
Thesearebioindicatorspeciesbecausetheirpresenceor
absenceinformsusabouttheconditionofthehabitat.

14. Abiotic factors affecting the abundance &
distribution of organisms
Wind
Thestrengthofthewindanditsdirectionhasahuge
impactonwhereorganismsarefoundwithinecosystems.
Manyorganismsprefermoreshelteredlocations.Plant
seedsaremorelikelytosettleandgerminatethere,and
animalswhichdependuponthesearemorelikelytolive
closetowheretheygrow.Thestrengthofthewindcan
alsoaffectthegrowthofindividualorganisms.

15. Two types of interactions between living things in their
environments are competitionand interdependence.
Competition vs Interdependence
Interdependence
Allorganismsinanecosystemdependuponeach
other.Ifthepopulationofoneorganismrisesorfalls,
thenthiscanaffecttherestoftheecosystem.

16. Competition vs Interdependence
Asimplefoodchainis:
Ifthefoxesinthefoodchainabovewerekilled,the
populationofrabbitswouldincreasebecausetheyareno
longerpreytothefoxes.Asaresulttheamountofgrass
woulddecreasebecausetheincreasedpopulationofrabbits
wouldbeeatingit.
Oftenverysmallchangestoecosystemshavelarge
consequences,whichcanbedifficulttopredict.Thismeans
thatalltheorganismsinanecosystemaredependentupon
eachother.Wecallthisinterdependence.

18. Competition vs Interdependence
Competitionisthestrugglebetweentwoorganismsfor
thesameresourceswithinanenvironment.Resources
arecomponentsoftheenvironmentthatarerequired
forsurvivalandreproductionsuchasfood,water,
shelter,light,territory,andsubstrate.Membersofthe
samespeciesmayalsocompeteformates.

19. Types of Competition
1.IntraspecificCompetition–Thecompetition
betweenorganismsofthesamespeciesfora
commonresource.

20. Types of Competition
2.InterspecificCompetition–Thecompetitionwhich
occursbetweenorganismsofdifferentspeciesfora
commonresource.

21. Interdependenceis the interaction between two or
more organisms where it is mutually beneficial.
Competition is the negative interaction between
two or more organisms which require the same
limited resource.
Remember, plant species can be interdependent.
They can also compete for resources such as light,
moisture and nutrients in the soil.

22. Read the information given about the four different situations. Use the
information to complete the table below.
How Factors Affect Populations
Description of
Scenario
Affecting
Factor
Abiotic or
Biotic?
Describe how species populations are
affected –increase or decrease
population? Explain why.
red and grey squirrels
cane toad introduction
to Australia
milkweed plant and
monarch butterflies
Chalaradieback of ash

23. Red and grey squirrels live in the same habitat and eat the same food.
Grey squirrels outcompete the red squirrels.
Red and Grey Squirrels

24. In 1935, cane toads were introduced to Australia as a biological pest control
of the grey-backed cane beetle.
The toads have no natural predators in Australia.
Cane Toads

25. The milkweed plant is pollinated by insects such as the monarch
butterfly. The monarch butterfly will only lay its eggs on milkweed
leaves. However, people often consider milkweed as an invasive weed
and use weed killers to remove them in their gardens.
Milkweed and Monarch Butterflies

26. In 2012, cases of Chalaradieback of
ash were discovered on ash trees
being imported from Europe. Later in
the year, it was discovered that ash
trees in established British woodland
showed signs of the disease.
Chalara Dieback of Ash