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GCSE AQA Combined Science Biology Paper 2 Notes.
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GCSE AQA Combined Science Biology Paper 2 Notes. All taken from the CGP guide. For Higher.
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Communities Abiotic factors that affect a Biotic factors (living), that cancommunity affect a community
= a population of two or more species.
1. Light intensity = required for Food availability= more
Populations are often dependent on each
photosynthesis, that affects food means organisms can
other.
rate of plant growth, plants breed more successfully,
Organisms need a supply of materials from can be foods sources or increase in population.
their surroundings and other organisms to shelters for organisms. New predators = upsets
survive and reproduce. 2. Temperature = affects rate the balance of the
photosynthesis. predators catching enough
When they need resources they compete for it
3. Moisture levels = plants and prey to survive but no so
Can be competition within a species or animals need water to many that all food is killed.
between different species. survive. New pathogens =
Plants may compete light, space, 4. Soil pH and mineral content = population has no
water, mineral ions. affects rate of decay, so how resistance to them so can
Animals territory, food, water, mating fast mineral ions return to be wiped out rapidly.
partners. soil. Competition = if one
5. Wind intensity and direction = species is better adapted
Interdependence
affects rate transpiration, that to the environment than
= one species depends on others for food, affects temp of plant and rate the other, it will
shelter, reproduction (pollination, seed photosynthesis. outcompete it until
dispersal), etc. 6. CO2 levels = rate numbers of lesser adapted
photosynthesis, distribution of species are insufficient to
organisms. breed.
7. O2 levels for aquatic animals
Stable community =levels in water vary greatly,
= where all the species (biotic) fish need high conc to survive.
and environmental factors
Quantitative data on the Required practical field investigations
(abiotic) are in balance, so
abundance and distribution
population sizes remain fairly Quadrats
of organisms can be
constant.
obtained by 1. On map of the area create grid.
Examples 2. Use random number generator to identify
1.random sampling with
Tropical rainforests, oak quadrats. coordinates. This increases validity.
woodlands, coral reefs. 3. Use a quadrat and count number of organisms
2.sampling along a transect in those random areas.
line. 4. Calculate the mean number of what you are
Adaptations
sampling across the area.
Adaptations
Structural = shape or colour part 5. Find the area of the field and then how many
of an organism Behavioural = way organism quadrats fit in it.
behaves 6. Times the amount of times the quadrat fits in
Sharp teeth of a
by the mean number.
carnivore to tear meat Individuals may play
apart. dead to avoid Changing environment
Camouflage, to avoid predators.
Transect line is laid out across changing terrain.
prey from spotting them. Basking in sun to
Quadrats placed at regular intervals across line.
Thick layer of fat for absorb heat.
Used to show links between organisms and
insulation for species in Courting behaviour to
abiotic factors.
cold environments. attract a male.
Adaptations Extremophiles
Functional = involved in processes such as reproduction and = live in environments which have extreme conditions.
metabolism. High temps, pressures or salt concs.
Late implantation of embryos. Example, bacteria, lives in deep sea vents, high pressure.
Conservation of water through producing little sweat.
Polar bear, Antarctic krill.
, Levels of organisation
Stable community shows Carbon cycle
Feeding relationships can be represented by food population cycles between
predators and prey 1.CO2 removed from air in
chains.
photosynthesis by green plant and
1. Producer Population prey increase, algae, they use carbon to make
Green plant or algae, photosynthesise population predator carbs, protein, fat. They are eaten
and make glucose, glucose used to make increase. and carbon moves up food chain.
other biological molecules in the plant, Results in number of prey
decreasing after time as 2.CO2 returned to air when plants,
makes up biomass.
more would be consumed algae and animals respire.
2. Eaten by primary consumers
by high number Decomposers respire will they
Energy is transferred through organisms
predators. return mineral ions to the soil.
in ecosystem when one eaten by other.
3. Eaten by secondary consumers When not enough prey to 3.CO2 returns to the air when
Animals eaten are prey, consumers are feed predators, predators wood and fossil fuels are burnt
predators. population decreases, (combustion) as they contain
4. Eaten by tertiary consumers. prey increases again. carbon from photosynthesis.
Water cycle Decomposers = group
Decay cycle microorganisms that break down
1.sun’s energy causes water to evaporate dead organisms and waste.
Returns carbon to the
from sea and lakes, forming water vapour.
atmosphere as CO2 and mineral
2.water vapour also formed as result of ions to the soil.
Role of microorganisms in cycling
transpiration In plants.
materials through an ecosystem
3.vapour rises and condenses to form
= help return minerals and nutrients
clouds. Decomposers are
back to environment so that they can
microorganisms that feed on
4.water returned to land by precipitation be used by other organisms.
dead organisms and their waste.
(rain,hail,snow) and runs into lakes to
They digest this material and use Break down
Humandead matter and
population release
effect on
provide water for plants and animals.
the nutrients to grow and the materials
land back to environment.
5.this then runs into seas and cycle starts reproduce. They release CO2 to
again. the atmosphere as they respire. Reduce number of habitats by
Human activities that are reducing Taking up land by building,
biodiversity quarrying (to find precious
metal ores), farming and
Producing waste, destruction dumping waste.
of habitats to make space for
landfill.
Deforestation, destruction of
forest habitats that have high
biodiversity.
Global warming, disruption of
ecosystem and biodiversity
due to flooding, coral
bleaching and extreme
weather.
Peat bogs land and humans Deforestation
= material that forms when plant material has not fully = cutting down of large number of trees in the same area, in
decayed as there is not enough O2. Releases C02 in atmosph. order to use the land for something else.
1. accumulates in bogs that are acidic and waterlogged. Happens to
2. They are habitats for many species, migrating birds.
3. They are being drained to create space for farming. Provide land for cattle and rice fields, to provide
4. Its used as a compost or dried to use as a fuel. more food.
5. Being used up quicker than it is formed, formation Grow crops from which biofuel can be produced.
process is slow.
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