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B2a: Ecology In Our School Grounds
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Different counting methods are: pooters, nets,
pitfall traps and quadrats
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You can estimate the population of a habitat using
quadrats and the calculation: total number of
quadrats x total area of habitat
total area of quadrats
 Mark-release-recapture is calculated as:
total caught first time x total caught second time
Number of marked ones caught second time
B2a: Ecology In Our School Grounds
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The bigger the sample size, the more reliable the
results
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A habitat is where an organisms lives- all the
different organisms living there is known as the
community
The community plus all the other non-living things
is called the ecosystem
Biodiversity means the number of different species
living there which is affected by the use of
herbicides, pesticides and fertilisers
Natural ecosystems are unaffected by humans,
artificial ecosystems are affected by humans e.g.
farmer’s fields, playing fields etc.
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B2b: Grouping Organisms
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Animals have cells with a nucleus, cell membrane
and cytoplasm. Plants cells have all of the above
plus cell walls, vacuole and chloroplasts
Fungi are neither plants or animals as they have
features of both, plus hyphae (long threads) that
form mycelium
Vertebrates have backbones, invertebrates do not
Fish have gills and scales, amphibians have wet
skin and lay eggs in water, reptiles have scales and
rubbery egg shells, birds have feathers and wings,
mammals are warm blooded and feed their young
on milk
B2b: Grouping Organisms
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B2c: The Food Factory
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B2c: The Food Factory
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Euglena and archaeopteryx don’t fit into any other
category so are known as protoctista
A species is a term for organisms that have similar
features and are able to interbreed to produce
fertile offspring
The binomial naming system gives all organisms
two names- one for their genus and one for their
species e.g. homo sapiens
A hybrid is the offspring of two closely related
species e.g. a mule and is usually infertile
Convergent evolution happens when two distantly
related species evolve similar characteristics due to
their environment
Carbon dioxide + water  glucose + oxygen
6CO2 + 6H2O  C6H1206 + 6O2
Glucose can be converted to starch and fats for
energy, cellulose for cell walls, and proteins for
growth and repair
Starch, fats and oils are good for storing energy as
they are big, compact and insoluble
The rate of photosynthesis can be increased by
providing more light or carbon dioxide, or a higher
temperature
Limiting factors are factors that prevent any more
photosynthesis from taking place e.g. carbon
dioxide or water
Plants respire all the time to release energy from
the glucose made during photosynthesis
During the day, plants photosynthesise and give
out more oxygen than they take in for respiration.
At night when photosynthesis stops, plants take in
more oxygen that they give out
B2d: Compete Or Die
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B2d: Compete Or Die
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B2e: Adapt To Fit
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Competition between species influences their
distribution e.g. large populations of wildebeests
live near the water supply and if there is not
enough they have to move
Competition within the same species means that
some organisms die as they are competing for the
same resource e.g. tadpoles in a pond
Organisms with the same ecological niche are
more likely to compete with each other e.g. red
and grey squirrels
The numbers of predators reduces the number of
prey and vice versa which can be shown on a
predator prey graph
A parasite is an organisms that lives in close
association with its host and does it harm e.g. cat
fleas and worms
Parasites are specialised- they can only live on or
around a particular host
Mutualism is when two different species live
closely together and they both get some benefit
e.g. ox and ox-pecker
Nitrogen fixing bacteria live in the root nodules of
leguminous plants- they put nitrogen from the air
into the soil
The adaptations of an organism determine where it
can live e.g. arctic
Organisms compete for limited resources like
food, water and shelter
Predators have sharp teeth, claws and binocular
vision
Prey have good hearing, camouflage and
monocular vision
B2e: Adapt To Fit
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B2f: Survival Of The Fittest
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Fish have a streamlined body and slimy mucus to
help them survive in the sea
Earthworms have a long body that helps them
burrow, they also have bristles on their underside
Bird’s feathers are light and provide insulationthey also have air spaces in their bones
Cacti have spines to deter animals and lower their
surface area
Insect pollinated plants have nectar and petals to
attract insects. Wind pollinated plants have
feathery stigma and light pollen
Fossils provide evidence for evolution
Organisms can be preserved for thousands of years
in amber, tar pits, peat bogs and ice
Fossils found in deep layers of rock are older than
fossils found in layers above them- we can tell
which animals lived at the same time this way
Biologists think that fossils show us how
organisms have changed over time- there are still
some people who think that fossils are found on
Everest because a biblical flood carried them up
there instead of the mountains rising up due to
earth movements
B2f: Survival Of The Fittest
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B2g: Population out of control
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B2g: Population Out Of Control
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Natural selection describes how the organisms
with random mutations that help them to survive
are more likely to survive, reproduce and pass on
their genes to the next generation
Peppered moths, antibiotic resistance in bacteria
and warfarin resistant rats are all examples of
natural selection not evolution
Charles Darwin correctly said that most species
have more young than ever survive, that there is
variation, competition, and the fittest survive to
pass on their genes
Lamarck wrongly said that acquired characteristics
could be passed on like a stretched giraffe neck
Speciation means that one species changes or
evolves into another due to factors like
geographical isolation
The human population has been increasing
exponentially (doubling), but this rate of increase
is now slowing down
The increasing human population means that we
use more of earth’s finite resources like coal, oil or
gas
Increasing population means that we produce more
pollutants, including carbon dioxide, sulphur
dioxide, CFC’s (which damage the ozone layer),
household waste and sewage
The environmental impact per person is greater in
developed countries than in developing countries
If the global population continues to increase, the
likely problems will be water shortages or food
shortages due to war or transport problems causing
pandemics (mass disease)
Indicator species can be used to monitor pollution
e.g. lichens which are only found where there is
low levels of sulphur dioxide
Indicator species like lichen and rat-tailed maggots
are given a number from the biotic index.
Organisms with a score of 10 can only live in
unpolluted environments
B2h: Sustainability
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B2h: Sustainability
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B2h: Sustainability
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Animals like the dodo and sabre toothed tiger went
extinct because of factors like climate change,
competition, hunting, habitat destruction and
pollution
Some of the ways that we can protect endangered
species are protecting habitats, legal protection,
education programmes, captive breeding
programmes and the creation of artificial
ecosystems
The IUCN publishes a list of all the species we are
aware of that are in danger of extinction- this is
called the red list
There are two groups of whales, toothed and
baleen that swim through the water and strain out
plankton
Whales migrate over large areas of the ocean to
other areas that contain the most plankton
Whales do not suffer from the bends, when they
dive, their lungs almost completely collapse. This
stops gases diffusing into the blood at high
pressure and causing them pain.
Whales have been used for meat, animal feed, oil
for lamps and cosmetics and whalebone corsets,
horsewhips and umbrellas
Whales have commercial value- People will pay to
see them in the wild
Keeping whales in captivity is a good thing as we
can learn more about them and keep them healthy,
but a bad thing is that they are kept in a small
space
The International Whaling Commission imposed a
ban on whaling in 1986, but lots of countries
disagree and it is too difficult to patrol
B2h: Sustainability
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A sustainable resource is one that we can go on
and on using, without using it up
Sustainable fishing means fish and fishing boat
quotas (limits) and bigger net size so young fish
can escape
Sustainable wood harvesting means coppicingcutting down part of the woodland and allowing
the rest to re-grow as apposed to clear-felling
(chopping down all the trees) which is much more
harmful to habitats
Local government authorities have planning rules
that people must follow and governments have
international meetings that commit countries to
being sustainable