Brown's Biology AQA GCSE Science-BIOLOGY 1 Revision Notes
Biology Unit B1.4 Interdependence and adaptation
BIOLOGY UNIT 1
for GCSE Science or GCSE Biology
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AQA GCSE Science BIOLOGY 1 Unit B1.4 Interdependence and adaptation
Appreciate that organisms are well adapted to survive in their normal environment.
Know that population
size depends on a variety of factors
including competition, predation, disease and human influences.
Know that changes in the
environment may affect the
distribution and behaviour of organisms.
Using your knowledge
and understanding be able to:
suggest how organisms are adapted to the
conditions in which they live,
observe the adaptations, eg body shape, of a range
of organisms from different habitats,
develop an understanding of the ways in which
adaptations enable organisms to survive,
suggest the factors for which organisms are
competing in a given habitat,
Factors will be limited to
light, water, space and nutrients in plants; food, mates and territory in
evaluate data concerned with the effect of
environmental changes on the distribution and
behaviour of living organisms.
AQA GCSE Science BIOLOGY Unit B1.4.1 Adaptations
a) Know and understand that to survive and reproduce,
organisms require a supply of materials from their surroundings and from the
other living organisms there.
b) Know and understand that plants often compete with
each other for light and space, and for water and nutrients from the soil.
c) Know and understand that animals often compete with
each other for food, water, mates and territory. In the wild territorial
disputes between species or members of a species are common - an example of
competition. Those animals who are best adapted will nudge out of other
species from a particular habitat.
In most UK woodlands, the grey
squirrel from North America, has displaced the native red squirrel,
principally because it out-competes for food. The grey squirrel can feed
more at ground level and can digest acorns and red squirrels can't).
d) Know and understand that organisms, including
microorganisms have features (adaptations) that enable them to survive in
the conditions in which they normally live.
e) Know and understand that some organisms live in
environments that are very extreme.
Know that so-called extremophiles may be tolerant to high levels
of salt, high temperatures or high pressures.
Flamingos filter-feed on brine
shrimp and blue-green algae and their pink or reddish color comes from
carotenoid proteins in their diet of animal and plant plankton which can
survive in the very salty lakes the flamingos fly to for feeding.
There are certain
microorganisms, eg bacteria colonies, that live by hot volcanic vents of
water on land (eg geysers) or on the seabed (where the vents are called
There are creatures that happily
live on the deep ocean beds where the pressure from the water above is
f) Know and understand animals and plants may be adapted for survival in
the conditions where they normally live, eg deserts,
Know and understand that
animals and plants may be adapted to cope with
specific features of their environment, these specialised features include thorns,
poisons and warning colours to deter predators eg
Roses have thorns, hedgehogs
have needle like spikes/spines over the upper side of their body and can
curl up to give all round protection, cacti have sharp spines to deter
animals (herbivores) eating them, turtles, armadillos and tortoises have
hard protective shells
Plants like ivy contain poisons,
insects like bees and wasps have stings, some desert shrubs secrete toxic
compounds into the soil to prevent other plants growing nearby
Some insects and other animals
have very bright colours to look 'fearful' to potential predators.
AQA GCSE Science BIOLOGY Unit B1.4.2 Environmental change
a) Know and understand that changes in the environment
affect the distribution of living organisms.
Exam question examples might
include, but not limited to, the changing distribution of some bird species
and the disappearance of pollinating insects, including bees.
b) Know and understand that animals and plants are
subjected to environmental changes.
Realise that such changes may be caused by living or
living: Change in
competitor (a new or rise/fall in native ones), spread of an infectious
disease from parasites and pathogens, levels of prey available to hunt,
One species population might be
affected by a 'living' factor. If it is the prey for some other animal, then
in turn the predator is affected, so population changes are frequent in the
animal world and can rise or fall significantly with the availability of
The decline in the bee
population in many countries is attributed to them carrying
pathogens/parasites and their food supply contaminated with pesticides - but
nobody is quite sure, what is sure, is that bees immune system can't cope.
The spread of Dutch elm disease,
and other diseases, are devastating tree populations.
non-living: Change in the average
temperature or rainfall,
The average temperature in some
northern European countries has risen, so populations of some bird species
from southern areas eg the Mediterranean countries, are beginning to
increase in northern Europe.
Acid rain, from the industrial
revolution onwards, has affected forests and ecosystems in lake by
decreasing the pH of water.
The English Channel separating
England and France has become slightly warmer (only by 0.5oC in
100 years), so species of animals from warmer waters are moving north-east
into warmer water ie the geographical distribution of marine life is
c) Know and understand that living organisms can be used
as indicators of environmental changes such as pollution.
Despite the presence of
pollutants, some species of plants/animals can live in polluted air or
water, but other organisms need clean air or clean water to survive and
The absence or presence of
these indicator species e.g. from monitored population counts,
can say much about whether a particular atmospheric or aquatic
environment is relatively polluted or unpolluted.
These indicator species can
be quite sensitive to their environment and we can put their sensitivity
to their surroundings to good use in environmental monitoring and
hopefully control things to improve matters.
indicators may live ...
... on surface exposed to
air e.g. lichen on rocks/stone walls, blackspot fungus on roses,
... live in water e.g.
mayfly larvae, stonefly larvae, freshwater shrimps, bloodworms,
Lichens can be used as
indicators, particularly of the concentration of sulfur dioxide in the
The cleaner the air in
the environment, the more varied species, and the greater numbers of
an individual species of lichen colonies are seen on rocks and stone
walls. You would observe the 'cleaner air' effect if you surveyed
walls all the way from a polluted town or city centre to some rural
location away from roads well beyond the town or city boundary, and
no doubt note the greater the numbers and variety of lichen growing
on the walls the further you where from the town/city centre.
species can be used as quite a sensitive air pollution indicator
i.e. low populations of a limited number of lichen species indicates
polluted air, usually from sulphur dioxide (SO2).
Particular lichens are
sensitive to poisonous sulfur dioxide (even in very low
concentrations of SO2) from fossil fuel burning -
road vehicle exhausts, power station chimneys etc.
Blackspot fungus readily
grows on roses in relatively clean unpolluted air, but does not grow
as readily in polluted air - the fungus is killed by the polluting
sulfur dioxide. One advantage an urban gardener has over a country
Invertebrate animals can be used as
water pollution indicators
and are used as indicators of the concentration of dissolved oxygen in
Lakes that are stagnant
from overgrowth of algae (eutrophication) become devoid of oxygen at
lower levels because the decay bacteria use up the oxygen. This
decreases invertebrate populations and animals that feed on them,
like fish, also decline - so whole food-chains and complex
ecosystems are disrupted.
If rivers become
polluted from raw sewage spills or silage spills, the concentration of
pathogens rise (extra food for them e.g. nitrate nutrients) and these microorganisms use up the
oxygen, so all species needing oxygen decline - which is nearly
Certain bacteria will
thrive in these conditions and consume oxygen in the process.
species actually thrive in low oxygen polluted water e.g. a high
population of blood worms and sludge worms indicates very polluted
animals like the mayfly larvae and stonefly nymphs are particularly
sensitive to pollution, so their population size is a very good
indicator of the purity of the water. The less pollution in the lake
or river water, the less the growth of algae/bacteria etc. and the more
oxygen dissolve in the water (less used up), therefore the more mayflies
and stoneflies hatched out for the trout! and more trout for the
fisherman! BUT only in clean unpolluted water!
d) Environmental changes can be
measured using non-living indicators (usually sensors) to monitor factors such as oxygen levels
in water, temperature and
You should understand the use of
equipment to measure oxygen levels, temperature and rainfall, all of which
are important indicators of environment change on land or in water and
the bigger picture of global climate change.
Special meter probes can
be dipped into water to measure oxygen levels, a bit like pH meter
probes that measure pH (which is also an important indicator of
relative acidity-alkalinity). A decline in aquatic oxygen levels as
measured by an oxygen probe gives an
immediate warning of pollution.
Temperature can be
measured directly and very accurately with a mercury thermometer
(being replaces on health and safety grounds),
or, electronically using a thermocouple system. Average temperatures
for the year, or seasonal averages, are important indicators of
climate change. Both air and sea temperatures are monitored.
instruments can automatically and continuously monitor air pollution
levels of carbon monoxide, sulphur dioxide and ozone levels in the
The data can be
continuously fed, stored and analysed in computer systems for
detailed analysis of air pollution patterns on a long-term basis, so
a decline or an improvement in environmental conditions can be seen
and its progress monitored.
You can do the same with
pH, oxygen level and temperature probes continually monitoring water
systems like rivers.
Rainfall is easily
monitored with a rain gauge, manually with a calibrated glass
container (a bit like a measuring cylinder), or automatically by
weighing the water collected with a sensitive balance. Like
temperature, rainfall is an important aspect of regional climate
All of these
monitoring systems can be fully automated these days and so
'automatic weather stations' can be set up in remote locations
and data sent by radio to a weather centre or laboratory.
Satellites are being
used to monitor several environmental factors eg decline of
forests by burning and replace with cattle or crops, the area of
ice/snow cover in arctic regions eg changes in the Greenland and
Antarctic ice sheets. Even individual remote glaciers can be
monitored - decline of some with temperature rise is concerning
climate scientists studying global warming.
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