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Slide 1

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Biology Unit 4
Populations and the
environment…read more

Slide 2

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Habitat ­ the place where an organism lives
Population ­ all the individuals of one particular
species found in a ecosystem at a given time
Community ­ sum of all organisms in a ecosystem
Abiotic ­ non living
Biotic ­ living
niche ­ how the species functions in its habitat
Adaption ­ a feature an organism has that
increases its chance of survival and reproduction
Birth rate -> number of births per 1000 people per
death rate -> number of deaths per 1000 people…read more

Slide 3

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Phosphorylation ­ adding a phosphate using
Photophosphorylation ­ adding a phosphate
using light
Photolysis ­ splitting of a molecule using light
Hydrolysis ­ splitting a molecule using water
Decarboxylation ­ removing carbon dioxide
Degydrogenation ­ the removal of a hydrogen
Reduction ­ gain of electrons and hydrogen,
loss of oxygen
Oxidation ­ loss of electrons and hydrogen,
gain of oxygen…read more

Slide 4

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Populations & Ecosystems
An ecosystem is a self supporting system of
organisms interacting with each other and
their physical environment
Interactions include:
- Competition for resources
- Feeding relationships
Every species occupies a different niche, they
have different eating patterns ect...
If a species tries to occupy the same niche then
they will compete, one will outcompete the
other.…read more

Slide 5

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Factors affecting population
Population size is dependent on the availability of
Biotic and abiotic factors can limit population
Main biotic factor = competition:
Interspecific -> competition between different
Intraspecific -> competition between same
Main abiotic factors:
CO concentration -> plant populations only
Mineral ion availability -> plant populations only
Light intensity -> plant population only…read more

Slide 6

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biotic factors that influence population size:
-predation -> reduces the prey population
-disease causing organisms ->population slowed
The predator prey relationship
the populations size of the predators and prey are
Increase in prey numbers means more food for
Predator numbers increase
Predators kill more prey, so prey population
Less food for predator, so predator population
Less predators to kill prey, so prey population
increases…read more

Slide 7

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Slide 8

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Slide 9

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Slide 10

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awful spelling is quite distracting, but apart from that it's concise and useful



Brilliant resource, thank you so much! Great to combine with my class notes :)

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