ecology Flashcards
what is a habitat
the place where an organism lives
population vs community
pop - all the organisms of one species living in a habitat
com - all the populations of different species living in a habitat
what do you call living/non living factors?
non living factors of the environment - abiotic
living factors of the environment - biotic
what abiotic factors can affect organisms in an ecosystem
- light intensity - can stunt plant growth, reducing food
- temperature - seasonal changes
- water level
- soil pH and mineral content
- wind intensity and direction
- co2 level (for plants)
- oxygen level (in water - for aquatic life)
what biotic factors can affect organisms in an ecosystem
- availability of food
- arrival of a new predator
- competition - number can become to low to breed if outcompeted
- new pathogens
what is an ecosystem
interaction of a community of the abiotic factors with biotic factors of an environment
describe stability in an ecosystem
interdependence: all species in a community depend on each other for food, shelter, pollination and seed dispersal
can be a stable community: organisms are in balance with each other & with abiotic factors. any changes may cause large knock on effects
what are the three ways of adaption?
Structural, behavioural, functional
what does structural adaptation mean and give the examples from an organism in a hot desert and an organism in a cold desert
changes to body structure eg shape or colour
camel - hump stores fat to allow heat loss, leathery mouth, long lash
arctic fox - thick fur, furry soles, and small ears all reduce heat loss. white coat for camouflage
what is behavioural adaption and give example
changes to behaviour eg migration
kangaroo rat - nocturnal to avoid heat and predators of daytime
what does functional adaptation mean and give example
changes to processes inside body
camel - concentrated urine & dry faeces to reduce water loss from
how is a cactus adapted
small leaves to reduce water loss, long horizontal roots to maximise rainfall collection, store water in leaves and stem
what is an extremophile and give example
organisms adapted to live in extreme conditions
bacteria in deep sea vent - can live in high temp, pressure, and salt concentration
importance of producers
they sythesise complex molecules, known as biomass, which pass down the food chain to other organisms
order of food chain
Producer
Primary consumer
Secondary consumer
Tertiary consumer
what pattern are predatory-prey cycles, and when might they be different
- rise and fall in cycles
- out of sync - takes a while for each population to respond to a change
only true in a stable community
what do the different sampling techniques measure
random sampling: uses quadrat to compare numbers of organisms (plants/slow animals) in different areas
sampling along a transect: uses transect to see how number of species change as we move across a habitat
how to estimate total population of daisies in a field
random sampling
- place two 20m tape measures at right angle
- use random number generator to select a random coordinate
- place quadrat at coordinate and count number of wanted organism in quadrat
- repeat large number of times to get accurate representation
- (total area/area sampled) x number of organisms in sample
how to investigate how a factor effects the distribution of a dasies across a field
sampling along a transect
- place transect across area effected outward
- at start of transect, use quadrat to count number of daisies, and measure factor using meter or an app
- move quadrat by 1m intervals and repeat to get accurate representation
- compare recordings to see effects
why might a factor, eg light intensity, not effect distribution of a species
other factors, eg different mineral content in soil
three factors that affect distribution of a species, and how they change to affect the distribution
Temperature
Availability of water
Composition of atmospheric gases
geographic variation
seasonal variation (migration)
human activity (gases we release in air and water)
what are the four steps of the water cycle/recycle?
- evaporation/transpiration (from plant)
- condensation
- Precipitation of fresh water
- water either: instant evaporation, forms aquifers, streams back to sea
- animals drink water, release as urine of exhalation
Order of carbon cycle
- CO2 removed from atmosphere by plants and algae. carbon used for carbs, fats, and proteins for cells
- some CO2 returned to atmosphere where plants respire
- CO2 is eaten and passed down chain of consumers. carbon used for carbs, fats, and proteins for cells.
- CO2 returned to atmosphere when animals respire aerobically
- carbon in excrement and dead remains of plants and animals, broken down by decomposers
- CO2 returned to atmosphere when decomposers respire
- when decomposition cannot occur, eg in unfavoured conditions, carbon in excrement and dead remains slowly converts to fossil fuels
- CO2 returned to atmosphere during combustion of fossil fuels
what is compost?
dead plant material that has decomposed to be used as natural fertiliser, as it is rich in minerals
What conditions create a fast rate of decay and why
warm temperature - optimal for enzymes, not hot
Moist environment - many chemical reactions in decay require water
good oxygen supply - decomposers respire aerobically
more decomposers eg bacteria
why might a compost heap that has already began to decay work faster than one that hasnt?
decomposers respire aerobically this releases energy, which creates warmer conditions, optimal for enzymes
how can farmers increase oxygen supply for compost
- holes in compost bin
- mix compost regularly with fork allows oxygen to enter and increases SA
what is anaerobic decay and how can it produce fuel
carried out by decomposers in absence of oxygen
it produces biogas, which can provide fuel using biogas generators
how to make milk decay investigation more accurate
deciding when solution has turned yellow is subjective.
share data with other groups and calculate mean
why does solution turn yellow when investigating decay of milk
the enzyme lipase breaks down fat molecules in milk. this releases fatty acids, causing milk to become acidic.
cresol red turns yellow in acid
how to investigate effect of temperature on decay of milk
- use pipette to place 5cm^3 lipase solution in a test tube and label “lipase”
- add five drops of indicator Cresol red, 5cm^3 milk, and 7cm^3 sodium carbonate into test tube. solution should be purple (alkaline). label “milk”
- place thermometer into “milk”
- place both tubes into 20 degrees beaker of water, until thermometer reads 20
- transfer 1cm^3 lipase solution to “milk”, stir, and start timer
- stop timer when indicator turns yellow (acid) and record result
- repeat at range of temps, ensuring milk tube is clean
- plot graph
What is biodiversity?
The variety of different species of organisms on earth or within an ecosystem
importance of biodiversity
Keeps ecosystem stable: species depend on each other and the environment for shelter and food
a high biodiversity means ecosystem is less dependent on one species
reasons for deforestation
- land space to grow crops for making biofuels
- land space for agriculture - rice crops, cattle
- land space for housing
what is population increase leading to
- more resources used
- more waste, more pollution
how does human activity pollute water
- sewage sometimes released into nearby waterways. though treated in uk, untreated sewage can still be accidentally released into rivers. urine & faeces causes dissolved oxygen levels to fall, killing aquatic organisms
- fertiliser can run into rivers, causing dissolved oxygen levels to fall, killing aquatic organisms
- factories can release toxic chemicals into rivers, killing aquatic organisms
how does human activity pollute the air
- burning coal in power stations releases smoke and acidic gases that cause acid rain, killing plants and animals
how does human activity pollute the land
- millions of tonnes of waste dumped in landfills, destroying habitats
- toxic chemicals leach out of landfill and pollute soil
- sometimes toxic chemicals dumped directly onto land
how does global warming work/greenhouse effect?
Increased greenhouse gases pollute the atmosphere. This absorbs more energy from the Sun and traps it
what do humans use land for
buildings
farms
quarries
landfill
what is a peat bog
large amounts of dead plant materials that decay very slowly due to lack of oxygen, meaning they contain a lot of trapped carbon
how do peat bogs reduce biodiversity and cause climate change
humans use peat:
- to produce cheap compost
- burned to release energy eg generate electricity
- peat bogs destroyed, damaging habitat, reducing biodiversity
- when extracted, peat becomes exposed to more oxygen, meaning it begins to decay, releasing co2
- burning peat for energy releases co2
why do we still use peat
peat-free compost alternatives are more expensive, and would increase food prices
how are humans causing climate change
- burning fossil fuels releases co2
- bacteria in paddy rice fields releases methane
- farming cows release methane when they pass wind
these gases cause greenhouse effect, trapping heat
why are scientific papers valid but media reports invalid
- scientific papers are peer reviewed by other scientists to detect false claims and ensure validity
- media reports are not peer reviewed, so can be oversimplified, inaccurate, or biased
how does global warming affect animals and plants
- loss of habitats eg glaciers
- change in species distribution, eg birds extend range northward to cooler conditions
- changes in migration patterns
- changes in seasonal activity eg plants flower earlier
how can we maintain biodiverstoy
- breeding programmes for endangered
- Habitat protection and regeneration
farmers
- leave field margins (strips of unfarmed land) around crops for wildflowers and animals, as crop fields have very low biodiversity
- plant hedgerows between fields to encourage biodiversity
mitigating global warming
- government steps to reduce deforestation, eg national parks
- government steps to reduce co2 emissions, eg renewables
Reducing deforestation
Reducing waste
- recycling to prevent landfill and preserve habitat
Dietary categories of each trophic level
One: producer
Two: herbivore
Three: carnivore
Four: carnivore
what is an apex predator
carnivores with no predators
how does decomposition work
Decomposers secrete enzymes that digest and break down dead plants and animals and waste products into small, soluble food molecules. these diffuse back into the decomposer
what is biomass and how is it calculated
the mass of all organisms on a certain trophic level
species collected, killed, dried, and weighed
how to plot biomass
pyramid formation
trophic 1, producer, at bottom
why does biomass decrease with each trophic level
- some converted to waste products and released eg urea
- not all material ingested is absorbed, some egested as faeces
- used by organism for respiration to release energy, biomass also used to produce waste products of respiration
why do most pyramids of biomass only have very little trophic levels
only 10% of biomass passes onto next level, meaning number of organisms at trophic level will decrease
formula for efficiency of biomass transfer
gain in biomass/biomass available
x100
biological threats of food security
- increasing birth rate, higher demand for food
- changing tastes, demand for larger variety eg foreign foods
- new pests and pathogens reduce crops
- environmental change, eg unpredictable weather causes famine
- resources eg fertilisers, pesticides, increasingly expensive
- conflicts can disrupt farming and imports
issue of overfishing
fish stocks fall, meaning there are not enough mature fish left to breed
Two ways to maintain fish stocks
fishing quotas – limits number of fish that can be caught so remaining fish can breed
net Size - reduce number of unwanted fish being killed. younger fish can escape and breed.
what is the aim of modern farming methods
improve efficiency of biomass transfer
issues of free range livestock
- movement requires respiration, biomass used
- energy required to keep warm, biomass used
less biomass available for animals to grow and produce food
advantages of factory farm
- Limits the movement which reduces energy transfer
- Energy not wasted maintaining temperature
- we can control their diets, eg high protein created more meat
more energy from biomass can be used for growth, more food produced
two disadvantages of factory farming
- Disease spread easily
- stress and fights more common
- Ethical objections
uses of biotechnology in food
increase nutritional value eg golden rice
use of microorganisms
what is golden rice
rice with improved nutritional value to reduce blindness
- natural rice does not contain molecules needed to make vitamin A, which is needed for effective vision
- rice genetically modified to contain these molecules
what is mycoprotein
produced by the microorganims fusarium, a fungus.
in aerobic conditions, the fungus converts the glucose syrup that it grows on into mycoprotein, which is harvested and purified to be made into products
mycoprotein advantages
- suitable for vegetarians
- large amounts can be grown in a small space - efficient
