ecology Flashcards
define an ecosystem
the interaction of a community of living (biotic) organisms with the non-living (abiotic) parts of their environment
what do organisms need to survive and reproduce
a supply of materials from their surroundings and from the other living organisms there
what do plants in a community or habitat often compete for
they often compete with each other for light and space, and for water and mineral ions from the soil
what do animals in a community or habitat often compete for
they often compete with each other for food, mates and territory
define a stable community
one where all the species and environmental factors are in balance so that population sizes remain fairly constant
define interdependence
within a community each species depends on other species for food, shelter, pollination, seed dispersal, etc. if one species is removed it can affect the whole community
list the abiotic factors which can affect a community
- light intensity
- temperature
- moisture levels
- soil pH and mineral content
- wind intensity and direction
- carbon dioxide levels for plants
- oxygen levels for aquatic animals
define habitat
the place where an organism lives
define a population
the total number of organisms of the same species living in the same geographical area
define a community
the populations of all the different species that live in the same habitat
how does increasing temperature affect a community and what factor is it
temperature = abiotic factor
it could cause the distribution of species to change - animals may migrate to cooler areas and plants may die due to high rates of transpiration
how does lack of light intensity affect a community and what factor is it
light intensity = abiotic factor
it’s needed for photosynthesis, so lack thereof could lead to decreased plant populations, leading to decreased food for animals
how does soil pH and mineral content affect a community and what factor is it
soil pH and mineral content = abiotic factor
plants cannot grow on soils too acidic or too alkaline, and they also need certain mineral ions in the soil
how do moisture levels affect a community and what factor is it
moisture level = abiotic factor
all organisms require water to survive
how does wind intensity affect a community and what factor is it
wind intensity = abiotic factor
can affect transpiration in plants
how do decreasing carbon dioxide levels affect a community and what factor is it
carbon dioxide levels = abiotic factor
it’s needed for photosynthesis, so lack thereof could lead to decreased plant populations, leading to decreased food for animals
how do oxygen levels affect a community of aquatic animals and what factor is it
oxygen levels = abiotic factor
oxygen is required for aerobic respiration. the level of oxygen in the air remains fairly constant, but dissolved oxygen levels are liable to fall on hot days, which can be dangerous for aquatic animals e.g., fish
list the biotic factors which can affect a community
- availability of food
- new predators arriving
- new pathogens
- one species outcompeting another so the numbers are no longer sufficient to breed
how does availability of food affect a community of aquatic animals and what factor is it
availability of food = biotic factor
all animals eat other living organisms - all sources of food are a biotic factor. if the availability of food decreases, then the number of organisms in the community will also fall
how does the arrival of new predators affect a community of aquatic animals and what factor is it
new predators arriving = biotic factor
this can cause the population or prey species to fall. it could also affect existing predators if they are competing for the same prey
how do new pathogens affect a community of aquatic animals and what factor is it
new pathogens = biotic factor
if a new disease emerges and spreads, it can wipe out a population of species
how does one species outcompeting another affect a community of aquatic animals and what factor is it
if a species is outcompeted, the numbers can decrease to the degree that the numbers are no longer sufficient for breeding and the species becomes extinct
define an adaptation
any feature that enables an organism to be a better competitor and be more likely to survive and reproduce within their environment
what can adaptations be + give examples
structural - i.e. physical features, e.g., camouflage
functional - how the body operates, e.g., sweating
behavioural - how the organism acts, e.g., hibernation
common adaptations for animals in cold climates
- thick fur coats
- layers of blubber under the skin
- fat, round body shapes with short legs (smaller SA:V ratio)
- small ears
common adaptations for animals in hot climates
- large thin ears
- little body fat
- thin fur
- long limbs to increase SA:V ratio
- long eyelashes
define extremophiles
organisms that live in very extreme environments, such as at high temperatures, pressures, or salt concentrations
state an example of an extremophile
bacteria living in deep sea vents
what are photosynthetic organisms
the producers of biomass for life on earth
what do all food chains begin with
producers - usually a green plant or alga
why are producers important in food chains
they synthesise complex molecules using the sun’s energy in photosynthesis to make glucose, which is called biomass. plants effectively generate biomass so that consumers along the food chain can eat it and live
what do food chains represent
feeding relationships within a community
what do ecologists use transects and quadrats for
to determine the distribution and abundance of species in an ecosystem
order of producers to tertiary consumers
producers -> primary consumers -> secondary consumers -> tertiary consumers
define a predator
a consumer that kills and eats other animals
define prey
an animal that is eaten by other animals
what happens in a stable community in terms of prey and predators
the numbers of predators and prey rise and fall in cycles
define biodiversity
the variety of all the different species of organisms on earth, or within an ecosystem
how does a great biodiversity ensure the stability of ecosystems
it reduces the dependence of one species on another for things like food, shelter and the maintenance of the physical environment - hence makes ecosystems more stable
what does the future of the human species rely on
us maintaining a good level of biodiversity
why is biodiversity reducing
due to many human activities; only recently have measures been taken to try to stop this reduction
what do humans depend on biodiversity for
sustained food growth, clean air, water, medicine, shelter
what happens if populations increase or decrease in an ecosystem
nature tends to restore the balance over time to maintain biodiversity
what do different materials cycle through
the abiotic and biotic components of an ecosystem
why are all materials in the living world recycled
to provide the building blocks for future organisms
what is the function of the carbon cycle
it returns carbon from organisms to the atmosphere as carbon dioxide, which is to be used by plants in photosynthesis
what is the function of the water cycle
it provides fresh water for plants and animals on land before draining into the seas - water is continuously evaporated and precipitated
what is the only way that carbon can enter the carbon cycle
photosynthesis
how does carbon dioxide return back to the atmosphere in the carbon cycle
by aerobic respiration
what two key processes does the carbon cycle involve
- photosynthesis; brings carbon into the cycle
- respiration; returns carbon back into the atmosphere
carbon cycle steps
- plants and algae take in carbon dioxide from atmosphere in photosynthesis
- carbon used to make carbs, fats and proteins which make up cells of plants and algae
- when they respire, some of carbon is released back to atmosphere as carbon dioxide
- plants and algae eaten by animals which can be eaten by other animals
- carbon that was in plants is now in animal cells
- animals respire so some carbon released back to atmosphere as carbon dioxide
- animals release waste products e.g., faeces, and all animals and plants die; releases carbon in waste products and in dead remains
- waste products and dead remains broken down by decomposing microorganisms e.g., bacteria and fungi
- when decomposers carry out respiration, carbon in the waste and dead remains returned to atmosphere as carbon dioxide
- they also release mineral ions into the soil
why are decomposers important
they cycle materials through an ecosystem
why do decomposers sometimes not function effectively and what effect does this have on the carbon cycle
under certain conditions e.g., a lack of oxygen. if this happens, carbon in dead remains slowly converted to fossil fuels. humans combust these fossil fuels, releasing a large amount of carbon dioxide back into the atmosphere.
water cycle steps
- energy from sun causes water to evaporate from surface of sea
- water vapour travels into air and cools down
- when it cools, water vapour condenses to form clouds
- water in clouds falls to ground as precipitation (rain, snow, hail, sleet)
- once it hits ground, some evaporates back into atmosphere as water vapour
- some passes through rocks and forms aquifers
- a lot of it forms river and streams, which eventually drains back into the sea
what do all forms of precipitation contain
fresh water - no salt
how do plants play a role in the water cycle
plants take up water in their roots; water moves up plant in xylem and passes out through stomata as water vapour (TRANSPIRATION)
how do animals play a role in the water cycle
animals take in water through food and drink. water released in urine, faeces and exhalation.
how does temperature affect the rate of decay of biological material
warmer temp = faster rate of decomposition as enzymes used by decomposers to break down plant materials are working faster as more kinetic energy. compost usually warm due to energy released by respiration from decomposers - compost must not get too hot or enzymes in decomposers could denature and decomposers could die.
how is compost made
gardeners put dead plant material (e.g., grass) onto compost heap. over time, bacteria and fungi decompose plant material and produce compost. they try to provide optimum conditions for rapid decay of waste biological material to produce the compost.
how is compost used
as a natural fertiliser for growing garden plants or crops - this works because compost is very rich in minerals needed by plants to grow
how does water affect the rate of decay of biological material
moister compost = faster rate of decomposition, as many chemical reactions involved in decay require water. gardeners must not allow compost heap to dry out.
how does availability of oxygen affect the rate of decay of biological material
oxygen needed for decomposers to aerobically respire to release energy needed for decay.compost bins have holes in walls to allow oxygen to enter
what is a gardening fork used for
- to mix compost regularly to allow more oxygen to pass into the centre
- to break up large clumps of compost which increases surface area for decomposers to act on
what is produced by anaerobic decay and how can this be used
methane - biogas generators can be used to produce methane gas as a fuel for homes
environmental changes that affect the distribution of species in an ecosystem
- temperature (geographic)
- availability of water (geographic)
- composition of atmospheric gases (human interaction)
changes may be seasonal, geographic or caused by human interaction
seasonal -> migration, e.g., bats migrating south to spend winter in mexico where conditions are warmer
what can changes in abiotic factors also effect
the distribution of species
how does composition of atmospheric gases affect lichens
lichens extremely sensitive to sulfur dioxide produced by burning fossil fuels - therefore large numbers found where air is unpolluted
how does composition of atmospheric gases affect levels of gases dissolved in water
if sewage is allowed into streams, oxygen levels drop. some aquatic organisms cannot live in low oxygen levels so populations fall.
how does increasing human population affect waste
rapid growth in human population and increase in standard of living means increasingly more resources are used and more waste is produced
under what condition is more pollution caused
if waste and chemical materials aren’t properly handled
state three ways pollution can occur in water
- sewage
- fertilisers
- toxic chemicals
how does sewage pollute water
- humans produce large amount of sewage containing urine and faeces
- some countries release into nearby waterways
- UK sewage treated before release - sometimes untreated sewage accidentally released into rivers or streams
how do fertilisers pollute water
- farmers add fertilisers to soil to ensure soil fertility year after year
- minerals in fertilisers (esp nitrates) easily washed from soil into local streams, rivers
- stimulates growth of algae and water plants; algae cover surface of pond
- too much competition for light so unable to photosynthesise; therefore less oxygen in pond
- plants die, decompose by bacteria and fungi which respire and use up even more oxygen
this is known as eutrophication
how do toxic chemicals (e.g., pesticides and herbicides) pollute water
- released into rivers from factories
- can kill animals in the river due to bioaccumulation effect
- largest carnivores die or fail to breed due to build up of toxic chemicals in their bodies
how do fertilisers and untreated sewage in water kill aquatic organisms
they cause dissolved oxygen levels to fall
- eventually fall so low that all aerobic aquatic animals die
what are bioindicators used for
monitoring pollution levels in waterways
state two ways pollution can occur in air
- smoke
- acidic gases
how does smoke pollute air
- burning fossil fuels releases smoke (unreacted hydrocarbon particulates)
- can suffocate certain animals
- can lead to lung damage and other respiratory complications
- can lead to global dimming; affects climate and hence affects distribution of many species
how do acidic gases pollute air
- human activities e.g., burning fossil fuels which often contain sulfur impurities
- sulfur reacts with oxygen during combustion to form sulfur dioxide; causes breathing problems in high concentrations
- leads to acid rain; destroys trees, soaks into soil and destroys roots, corrodes limestone buildings, can destroy whole ecosystems, alters pH of water - kills aquatic animals
what is smog and how is it caused
- a haze of small particles and acidic gases
- caused from sulfur dioxide and nitrogen oxides
state two ways pollution can occur on land
- landfill
- toxic chemicals
- side effect of farming
how does landfill pollute land
- destroys natural habitats for plants and animals
how do toxic chemicals pollute land
- can leach out of landfills and contaminate soil for miles around
- in some cases they’re dumped directly onto the land
- chemicals can kill living organisms
how does farming pollute land
- farmers use chemicals to protect crops
- these pesticides/herbicides are poisons
- when sprayed onto crops, they also get into soil
- from soil, washed out into streams and rivers
- can also enter food chains and bioaccumulate
- leads to dangerous levels of poisons building up in top predators
how does pollution reduce biodiversity
by killing plants and animals
how do humans reduce availability of land and what is the effect of this
by building, quarrying, farming and dumping waste, which reduces biodiversity as there are hence less habitats for plants and animals
what do peat bogs contain
large amounts of dead plant material that decays very slowly
why do peat bogs decay slowly
due to the anaerobic (without oxygen) and acidic conditions. also because of the waterlogging, as water cannot evaporate
how do peat bogs act as unique ecosystems
they act as a habitat for a wide range of organisms, meaning they have a rich biodiversity
what is a peat bog
a wetland in which peat has accumulated
what do peat bogs act as
a massive store of trapped carbon
uses of peat
- cheap compost for gardens
- good source of fuel
- sometimes burnt to generate energy i.e., electricity
disadvantages of destroying peat bogs
- they’re being destroyed faster than they form
- destruction of habitats which reduces the variety of different plant, animal and microorganism species that live there (biodiversity)
- high CO2 emissions
how do peat bogs contribute to climate change
- once it has been extracted for use in compost, it begins to decay
- this releases large amounts of CO2 into the atmosphere
- when it is burnt for fuels it releases CO2 as well
- CO2 is a greenhouse gas which contributes to climate change
what is the disadvantage of peat-free compost
its more expensive so would increase price of food as farmers pay more to grow crops using the peat-free compost
what has large-scale deforestation in tropical areas occurred to do
- provide land for cattle and rice fields
- grow crops for biofuels
disadvantages of deforestation
- disturbance of water cycle due to lack of evap from trees
- increased co2 levels due to lack of photosyn from trees
- burning trees releases co2 as it combusts
- microorganisms feeding on decaying vegetation releases co2 via respiration
- reduction in biodiversity, destruction of habitats and disruption of food chains - animals have less space to hunt + less prey to eat + less hiding space for prey
advantages of deforestation
- allows us to meet increasing demands for food as we have more room to grow food
- we can grow staple foods e.g., rice, or make cheap food in the developed world e.g., palm oil
- more space to rear cattle for beef market
- to grow crops used to make biofuel e.g., ethanol from sugarcane
where has the scientific consenus about global warming and climate change come from
it’s based on systematic reviews of thousands of peer reviewed publications - this helps to detect false claims and bias to ensure that research published in scientific journals is valid and accurate
why do reports in the popular media not contain accurate information about global warming
they’re not subject to peer review meaning it can sometimes be oversimplified, inaccurate or biased
what contributes to global warming
increasing levels of carbon dioxide and methane in the atmosphere
how does global warming affect the distribution of species
animals may migrate to cooler areas which affects migration patterns
how does global warming cause loss of habitats
- in polar regions for example, polar bears lose their ice habitats, reducing biodiversity
- rising sea levels destroys habitats especially in low-lying areas
how does global warming reduce overall biodiversity
- some organisms and species may not survive increased temperatures
- some organisms cannot migrate if other habitats don’t have the right food source
- many become extinct due to loss of habitat and changing conditions
how can global warming spread disease
mosquitoes as an example
- right now the temperature is too cold for species of mosquito to survive in the UK
- possible that with global warming, temperature becomes hot enough for them to migrate here
- diseases such as malaria may be brought with them
how can global warming affect plants
- plants flower earlier due to warmer conditions
- we may be able to grow crops in parts of the UK that need warmer temperatures if global warming increases
- in other parts of the world it may be too hot to grow the crops they need
programmes designed to maintain biodiversity
- breeding programmes for endangered species
- protection and regeneration of rare habitats
- reintroduction of field margins and hedgerows in agricultural areas where farmers employ monoculture
- reduction of deforestation and co2 emissions by some governments
- recycling resources rather than dumping waste in landfill
how do field margins and hedgerows on farms increase biodiversity
- lots of different species of plants and animals use these as habitats
- hence helps increase biodiversity on farms
how do governments play a role in maintaining biodiversity
- taking action to reduce co2 emissions
e.g., generating electricity by renewable methods which doesn’t contribute to global warming
how does recycling play a role in maintaining biodiversity
- waste would otherwise go to landfill
- landfill destroys habitats for plant and animal species’
- this means fewer habitats destroyed which has a positive effect on biodiversity
why have scientists and concerned citizens put programmes in place for biodiversity
to reduce the negative effects of humans on ecosystems and hence biodiversity
how are trophic levels used
they’re represented by numbers starting at level 1 (producers). further trophic levels are numbered subsequently according to how far the organism is along the food chain
what is on trophic level 1
producers - plants and algae that make their own food
what is on trophic level 2
primary consumers - herbivores that eat plants/algae
what is on trophic level 3
secondary consumers - carnivores that eat herbivores
what is on trophic level 4
tertiary consumers - carnivores that eat other carnivores
define apex predators
carnivores with no natural predators (top of the food chain)
what do decomposers do and how
they break down plant and animal matter by secreting enzymes into the environment. enzymes digest the dead materials and the small soluble food molecules then diffuse back into the decomposer (the microorganism)
what do pyramids of biomass represent
the relative amount of biomass in each level of a food chain - trophic level 1 is at the bottom of the pyramid
what causes losses of biomass between the different trophic levels
- not all ingested material is absorbed; some is egested as faeces
- some absorbed material is lost as waste, such as carbon dioxide and water in respiration, and water and urea in urine
what percentage of biomass is transferred to the trophic level above it
only approximately 10%
how much incident energy do producers transfer
they transfer about 1% of the incident energy from light for photosynthesis
how to calculate biomass of caterpillars in an area
- gather them
- kill them
- dry them out
- weigh them
this gives us the dry biomass
features of compost bins
- open at the bottom; lets decomposers enter
- some have air holes; allows oxygen in for decomposers to respire
- black in colour; absorbs heat to increase temp (faster rate of reaction)
- loosely fitting lid; allows oxygen in for decomposers to respire
what is the problem with measuring dry biomass
it will kill the organism as you’re dehydrating it
why is wet biomass less useful than dry biomass
moisture content varies between organisms so can give inaccurate results
define biomass
the (often dry) mass of material in living organisms
define food security
having enough food to feed a population
biological factors threatening food security
- increasing birth rate
- changing diets
- new pests and pathogens
- environmental changes
- cost of agricultural inputs
- conflict
how does increasing birth rate affect food security
as population grows, amount of food available will have to increase to feed the whole population
how do changing diets affect food security
- in developed countries, tastes are changing
- we now expect to eat a whole range of different foods throughout the year which cannot be grown in that country
- therefore scarce food resources are transported around the world which can threaten their food security
how do new pests and pathogens affect food security
- pests eat food crops e.g., caterpillars
- pathogens cause infectious diseases
- if spread to farms, this reduces the amount of food crops available to eat
how does environmental change affect food security
- changes rainfall patterns; some countries may not be able to grow enough crops to feed a population
- leads to widespread famine
how does cost of agricultural inputs affect food security
- GM crops withstand environmental change to increase yield; increases cost of seed so more expensive; makes it less affordable for consumers
- irrigation systems, fertilisers and pesticides all cost; thus reducing food security for some
how does conflict affect food security
- violence prevents planting
- no crops growing means stores are depleted
- little to harvest and violence means markets are closed
- food runs out
- labourers like farmers that are needed to grow crops leave the country out of fear of safety
- lack of migrant workers like farmers come to grow crops
- highly unlikely that food imports are possible
- country becomes over reliant on aid and donations which reduces food security
how can we feed all people on earth
by finding sustainable methods
how can the efficiency of food production be improved? how can this be done?
by restricting energy transfer from food animals to the environment which can be done by:
- limiting their movement; less energy used to move around
- controlling the temperature of their surroundings; less energy used to regulate their body temp themselves
- fed high protein foods to increase growth
ethical objections to some modern intensive farming methods
- poor animal welfare
- some people think it’s cruel
- livestock in confined spaces are more prone to disease
- unethical to make livestock live in unnatural and uncomfortable conditions
why are movement and temperature control restricted in intensive farming
both of these processes use the energy released from respiration. more energy is therefore available for growth as livestock don’t have to carry out these processes
advantages of modern farming techniques
- use less energy for movement so more energy used for growth
- antibiotics prevent diseases and bacterial in livestock kept in close proximity to each other
- monoculture maximises yield and profits for farmers
- fertilisers increase plant growth and therefore maximise food production
- removing hedgerows makes farms bigger and easier to maintain; more land available for crops
disadvantages of modern farming techniques
- keeping animals in close proximity is argued unethical as disease can spread easily
- use of antibiotics can lead to antibiotic resistance
- monocultures support a low level of biodiversity
- runoff from fertilisers leads to eutrophication and eventually the death of aquatic organisms
- removing hedgerows reduces biodiversity as they act as a habitat for a wide range of organisms
what is happening to fish stocks right now? why is this potentially dangerous?
they’re declining, mainly due to overfishing. it is important to maintain fish at a level where breeding continues or certain species may disappear altogether in some areas
consequences of overfishing
- some species disappearing or even going extinct
- ocean food chains being disrupted, affecting many other aquatic species
- fewer fish for human consumption; especially problematic for countries that rely on fish as a main food source
restrictions on fishing
- fishing quotas to conserve fish stocks at a sustainable level; limit number of fish you can catch
- larger holes in nets to allow small, young fish to escape and reach breeding age before they are caught and killed, which replenishes population of fish species
- larger holes in nets so unwanted fish species can escape provided they’re smaller than the target species
define biotechnology
the alteration and use of living organisms to produce products for human use
what do modern biotechnology techniques enable
large quantities of microorganisms to be cultured for food
modern biotechnology techniques
- genetic modification
- ability to culture large quantities of microorganisms for food
what are the hopes for modern biotechnology
that it may be able to help provide sufficient food for the increasing human population
what is fusarium and what is it used for
a fungus useful or producing mycoprotein, a protein-rich food suitable for vegetarians
how is fusarium grown
- grown on glucose syrup to allow respiration
- aerobic conditions
- the biomass is harvested and purified
fermenters are kept at optimum pH and temperature for fusarium to grow
how can we produce insulin with biotechnology
- gene for human insulin inserted into bacteria
- bacteria then produce human insulin which can be harvested and purified
- used medically to treat people with diabetes
how can GM crops be used to cater for increasing human population
- they can provide more food
- they can provide food with an improved nutritional value e.g., golden rice
