Ecology and the Environment Flashcards
population
all individuals of one species at one place at one time. E.g. all magpies in my garden at one time
community
all populations at one place at one time. E.g. every living organism (animals, plants) in my garden at one time
habitat
the places where a specific organism lives (whales - the ocean)
ecosystem
as all the biotic factors and all the abiotic factors that interact within an area at one time (eg a garden pond)
species
one type of creature (eg hoeosapions)
4.2 - practical investigate the population size of an organism in 2 different areas using quadrats
- use 2 tape measures to lay out a survey area (eg 10m x 10m)
- use a random number generator to create a set of coordinates to place the quadrat
- count the number of chosen species within the quadrat
- repeat steps 2-3 10x
- estimate the number of species in entire area with the formula:
find mean species per quadrat x total area of survey area
repeat entire process in a different area
whats a quadrat
Quadrats are square frames made of wood or wire
They can be a variety of sizes eg. 0.25m2 or 1m2
They are placed on the ground and the organisms within them are recorded
what can quadrats measure
The number of an individual species: the total number of individuals of a single species (eg. buttercups) is recorded
Species richness: the total number of different species (but not the number of individuals of each species) is recorded
Percentage cover: the approximate percentage of the quadrat area in which an individual species is found is recorded (this method is used when it is difficult to count individuals of the plant species being recorded eg. grass or moss
biotic factors
living
Competition
Predator-prey relationships
Interactions with other organisms within the food chain or food web
abiotic factors
non-living
Light intensity
Mineral availability
Water availability
pH
Temperature
what does biodiversity mean
the range and variety of different species of organisms on Earth, or within an ecosystem
It considers not only the species richness but the variation within each species, its distribution and population size
E.g. a high biodiversity would be found in an environment with lots of different species which show a lot of variation and are living in, all evenly distributed across the study area
4.4B practical - investigate the distribution of organisms in their habitats and measure biodiversity using quadrats
- Use 2 tape measures to lay out your first survey area (e.g. 10m X 10m)
- Use a random number generator to create a set of coordinates to place your first quadrat
- Count the number of different species and the number of each species found within that quadrat
- Repeat this process until you have collected the data for 10 quadrats
- Repeat these steps for the second survey area
the area with the greatest number of different species and the number of each species
species evenness
total number of organisms of each species in a place
for example if there was 2 oak trees, 2 spruce trees and 2 birch trees in one place and
4 oak trees, 1 spruce tree and 1 birch tree in another place
the first place would have the good evenness
species richness
the number of different species present in a place
eg. oak, spruce, birch, jungle = 4
how does light intensity affect communities
abiotic
light is needed to photosynthesis. more light leads to an increase in photosynthesis rate and an increase in plant growth
how does temperature affect communities
abiotic
affects photosynthesis rate in plants and therefore growth in plants
how does moisture levels affect communities
abiotic
plants and animals require water to survive
how does soil pH and mineral content affect communities
abiotic
less mineral ions will negatively affect plants as they won’t be able to osmosis as well
changing pH affects plants as they are adapted for certain conditions
how does CO2 levels affect communities
abiotic
CO2 is required for photosynthesis so CO2 conc affects photosynthesis rate
how does O2 levels affect aquatic animals
abiotic
affects aquatic animals as they can only survive in water with high O2 conc
availability of food
biotic
more food means organisms have a higher chance of survival and reproducing. this means the population will increase
new predators
biotic
in balanced ecosystems predators catch enough prey to survive but not enough to wipe out the population. if a new predator is introduced then it could unbalance the ecosystem
new pathogens
biotic
if a new pathogen enters an ecosystem the populations living their will no longer have immunity which will put the populations in decline
competition
biotic
if 2 species compete for the same resources and one is better equipped to to take advantage of the food, the better equipped one will get the resources meaning the other species will decline
producer
they produce their own energy
eg plants photosynthesing
primary consumer
the organisms which eat the producer
eg sheep who eat the grass
tertiary consumer
feed on the secondary consumer
secondary consumer
feed on the primary consumer
what is a trophic level
a different stage of a food chain
eg one trophic level might be the primary consumers
decomposer
organisms (bacteria and fungi) which secrete digestive enzymes to decay dead organic matter to obtain their food, these help recycle nutrients
what does a food chain show
a simple way to show the feeding interactions between organisms in a community
the arrows show the direction that the energy is travelling in
what does a food web show
shows a more complex version and accurate version of the feeding interactions between the organisms in a community
can also show interdependence (how the change in one population can affect others)
what does a pyramid of number show
A pyramid of numbers shows how many organisms at each level of a food chain.
You cannot change the trophic level of the organisms - they must stay in the same order as in the food chain with producers on the bottom, followed by primary consumers, then secondary consumers, then tertiary consumers
this is why the pyramid of number is slightly flawed
the pyramids always has the first thing on the food chain at the bottom and then the second and etc
what does a pyramid of biomass show
shows the total mass of the organisms in each trophic level (i.e. the mass of an individual x the number of individuals).
These are a more accurate way of looking at the relative amounts of organisms
these are always more like a normal pyramid
This is because the mass of organisms has to decrease as you go up a food chain – if we take our first food chain as an example, it’s impossible to have 10kg of grass-feeding 50kg of voles feeding 100kg of barn owls
what does a pyramid of energy transfer show
Pyramids of energy illustrate the amount of energy contained within the biomass of individuals within different trophic levels
The area of each box represents the quantity of energy present
These pyramids always have a wide base (due to the large amount of energy contained within the biomass of producers)
As you move up the pyramid to higher trophic levels the quantity of energy decreases as not all energy is transferred to the biomass of the next trophic level (roughly only 10 % of the energy is passed on)
how does the transfer of energy and substances work in a food chain
Energy flows from the sun to the first trophic level (producers) in the form of light
Producers convert light energy into chemical energy
This occurs during photosynthesis, when producers convert carbon dioxide and water into glucose and oxygen
Producers use this glucose (during respiration) to produce their own biomass
When primary consumers consume (eat) producers, they break down the biomass of the producer (digestion) and use the chemical energy to increase or sustain their own biomass
When secondary consumers consume (eat) primary consumers, they break down the biomass of the primary consumer (digestion) and use the chemical energy to increase or sustain their own biomass, and so on
In this way, as chemical energy is transferred from one trophic level to the next, biomass is also transferred
what is biomass
Biomass is a store of chemical energy
how much energy is lost between each trophic level
ruffly 90% is lost between each trophic level
why do food chains rarely contain more than 6 trophic levels
the total amount of energy available eventually becomes too small to support another trophic level as 90% is lost between each level
how is energy lost at each trophic level
Organisms rarely eat every part of the organism they are consuming – some of the biological material of plants and animals may be inedible
Not all the ingested material is digested and absorbed, some is egested as faeces
Energy is used for movement
Energy is used to generate heat
Energy is used for metabolic processes
Some absorbed material is lost as waste:
Carbon dioxide and water are waste products of respiration
Water and urea are the waste products in the urine, which is produced when proteins are broken down
what is the role of the nitrogen fixing bacteria
takes N2 gas and change it into nitrates in the soil
what is the role of decomposers
When the animals and plants die, they decay and all the proteins inside them are broken down into ammonium compounds and put back into the soil
what is the role of nitrifying bacteria
convert the ammonium compounds (from the decomposers) to nitrites and then to nitrates
what is the role of denitrifying bacteria
take the nitrates out of the soil and convert them back into N2 gas
why can’t animals and plants absorb nitrogen out of the air
N2 gas is very stable and the bonds holding the nitrogen atoms together would need massive amounts of energy to break (the two nitrogen atoms in a nitrogen molecule are held together by a triple covalent bond)
why do we need nitrogen
Nitrogen as an element is required to make proteins
what is nitrogen fixing
nitrogen taken out of the air and converted into something easier to absorb such as nitrates
what nitrogen fixes
lightning
nitrogen fixing bacteria
how does lighting nitrogen fix
splitting the bond between the two atoms and turning them into nitrous oxides like N2O and NO2 that dissolve in rainwater and ‘leach’ into the soil
how does the fixed nitrogen get removed from the soil
denitrification (bad denitrifying bacteria)
plants actively transport N ions into their roots
how does nitrogen get put into the soil
nitrogen fixing (lighting or nitrogen fixing bacteria)
nitrification (nitrifying bacteria)
how do animals get nitrogen
eat the plants (or other animals) which contain amino acids and proteins
how do plants get nitrogen
plants actively transport N ions into their roots
how do animals get rid of the nitrogen
waste (urine and faeces) which puts the nitrogen back into the soil as ammonium compounds
how does denitrifying bacteria work
they are found in poorly aerated soil which mean they respire anaerobically which puts the nitrogen straight out of the soil and into the air again
how to prevent denitrifying bacteria
by ploughing and turning over soil (aerating)
how is carbon put into the soil
decaying waste
fossilisation of dead plants and animals occurs in specific conditions
how is carbon taken out of the soil
carbon in dead and decaying matter is broken down by decomposers
carbon stored in fossil fuels is extracted
how is carbon put into the atmosphere
carbon is released when fossil fuels are burned in factories or cars or planes (combustion)
carbon is released during respiration of plants, animals and decomposers
plants are eaten by animals which then respire as well
how is carbon taken out of the atmosphere
photosynthesis from plants
biological consequences of pollution of air by sulfer dioxide
acid rain can damage plants and animals and also make rivers + lakes acidic damaging aquatic organisms.
can also cause leaching of toxic minerals into lakes
what are the greenhouse gases
Water vapour
Carbon dioxide
Methane
Nitrous oxides
CFCs - Chlorofluorocarbons
biological consequences of pollution of air by carbon monoxide
CO binds irreversibly to hemoglobin in red blood cells forming (carboxyhaemoglobin), preventing them from carrying oxygen to vital organs like the heart and brain
how does an increase in greenhouse gases result in an enhanced greenhouse effect
The Sun emits rays that enter the Earth’s atmosphere
The heat bounces back from the Earth’s surface
Some heat is reflected back out into space
Some heat is absorbed by greenhouse gases and is trapped within the Earth’s atmosphere – this is normal
However, as the levels of greenhouse gases in the atmosphere rise due to human activities the atmosphere gets thicker and traps more heat causing the earth to heat up more than usual making it the enhanced greenhouse effect
how have human activities contributed to greenhouse gases
Carbon dioxide is produced during the combustion of fossil fuel
Methane is produced by cattle as they digest grass and released by rice paddy fields
Deforestation: Clearing forests reduces the Earth’s capacity to absorb CO₂ through photosynthesis
consequences of global warming
Ocean temperatures increasing, causing melting of polar ice caps / rising sea levels / flooding / coral bleaching
Increasing temperatures causing extreme weather like super storms, flooding, droughts
Changes in or loss of habitats due to these extreme weather events
Decreases in biodiversity as food chains are disrupted and extinction rates increase
Increases in migration of species to new places, including increased spread of pests and disease
what are the biological consequences of pollution of water by sewage
toxic chemicals can’t be broken down and so build up and bioaccumulation and may even build up to toxic levels (biomagnifacation)
untreated sewage - sewage provides a good source of food for decomposers which therefore breed and with more they use up oxygen in the water when respiring aerobically. This lack of oxygen in the water causes death of other aquatic organisms as they don’t have enough oxygen. The death of these organisms causes more food for decomposers and the process repeats. (eutrphacation)
what are the biological consequences of eutrophication caused by leached minerals from fertiliser
fertilisers - cause increase in growth in aquatic plants meaning less light reaches the bottom of the water so plants die when provides more food for the decomposers which therefore breed and with more they use up oxygen in the water when respiring aerobically. This lack of oxygen in the water causes death of other aquatic organisms as they don’t have enough oxygen. The death of these organisms causes more food for decomposers and the process repeats. (eutrphacation)
effects of deforestation
leaching - if there is deforestation then there are less trees to uptake water so the water runs off into lakes and rivers. This means the mineral ions are removed from the soil and some of these nutrients (especially nitrates), can lead to further problems such as eutrophication
soil erosion - The water running off from deforested areas may carry away some of the topsoil, causing erosion. Because of deforestation there are no plants present in the soil and therefore there are no roots holding the soil in place. The topsoil contains the most fertile, mineral ion rich materials: when it is lost due to erosion the minerals are also lost, making the land very difficult to use for crop growth and reducing the chance of plants re-growing.
evapotranspiration - water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants. Transpiration is the evaporation and diffusion of water through the stomata of leaves. This evaporated water moves into the atmosphere and eventually (through the water cycle) makes rain in rain clouds. These rain clouds when then rain onto the plants, and the cycle will continue. When deforestation occurs, this cycle is broken.
carbon cycle - trees photosynthesis and so when you cut them down they can’t meaning that less carbon dioxide gets converted back into oxygen breaking the cycle. The cut down trees are usually burnt aswell which adds more carbon back into the atmosphere
imbalance of atmospheric gases - more CO2 in atmosphere and less O2 as trees don’t photosynthesis as they are cut down
