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Unit 4: Natural environment and Species Survival
Topic 5: On the wild side
5.1: The Biosphere

Biosphere: an area or a fraction of the Earth that is covered by living organisms.
-it is made up of many ecosystems.

An ecosystem is the community of organism interacting between themselves and the…

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Biotic factors: are dependent on the number of organisms there are compared with the resources
Are density dependant

Plants compete for space, light and minerals.
Animals compete for food, shelter and a mate.

When the fastest competitor wins:
It eliminates
dominates the other species, is called competitive exclusion.…

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Entirely new soil, surface, growth medium etc..
New land can form at river deltas, sand dunes and volcanic lava.

The first significant development is the formation of soil.
-Initial medium such as rock is eroded down over time to form most of the soil.
-external minerals can however be involved.…

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This occurs when an existing community is destroyed.
-Soil here is already present.
New species will come in due to dispersal etc...
-the species overtime will die and then carry on to develop into a new climax community.

Figure 2: Secondary Succession

Figure 2 ©Encyclopaedia Britannica D

Deflected succession is…

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(Also carnivores), eat other consumers. The carnivores at the top of the food chain are called the
top carnivores or the apex predators.

Animals that eat plants and plant matter.

Figure 3: Food chain:

Figure 3

The energy transfer in an ecosystem can be represented in a food…

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Fungi and bacteria
-feed on dead remains of organisms and excrement.
-they secrete enzymes to break down food before absorbing nutrients.

Efficiency of energy through ecosystem:
Dependant on how much energy is,
-captured by producers
-given to high trophic levels

Plants are not 100% efficient at absorbing light,…

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Efficiency (E):

E = (NPP
GPP )×100

Disappearance of energy:
Energy is lost as it enters higher trophic levels, but where does it go?
-not all food available is eaten: limitations of feeding methods and some parts of plants will not
get eaten.
-some energy is lost in faeces and…

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Figure 4 ©S-cool revision site

5.2: Climate Change

Evidence for Climate change:
Personal memory or `anecdotal' memory cannot be trusted to tell us if climate is changing.
We however have three different ways that we can tell climate change:
-Temperature records
-Pollen in beat bogs

Temperature records:
-Over time…

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One of the main things connected with Climate change is Global Warming.
-It's the gradual increase of temperature over time.

Greenhouse effect:
-The sun releases energy mostly as light.
-Most ultraviolet (UV) is absorbed by Stratosphere.
-The Earth absorbs some of this.
-The Earth warms up and radiates some of…

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Weather changes: At poles, cold, salty water sinks. Warm surface water replaces this. Melting ice
means less salinity. Slowing down of ocean currents are then a result of this. There are also
alterations in the patterns of heat and rainfall.

Coral Bleaching:
Microscopic algae live symbiotically with coral. When there…


Khadijah AG


Thanks! These are great notes

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