Ecosystems and Ecology Flashcards
big topic
What is a species?
It is a group of organisms that share similar features and can reproduce with one another in nature to produce fertile offspring
What does natality mean?
Natality is the birth rate
What does mortality mean?
Mortality is the death rate
What is the difference between immigration and emigration?
Immigration is moving into a country whereas emigration is moving out of a country
What is a niche?
The role an organism plays in an ecosystem
Give examples of a role that an organism can have
- if its a predator or a prey
- where is lives
- what its job is, i.e. a pollinator
- if it is nocturnal or diurnal
What are abiotic factors and give 3 examples
Non-living factors. i.e. turbidity, pH, temperature
What are biotic factors and give 3 examples
Living factors. i.e. disease, competition, predation
Two species of bird in a rainforest. They both live in the same tree and eat the same fruit from the tree. How can they both survive?
They can both survive in two ways:
1. One is nocturnal and one is diurnal
2. One lives in the upper canopy of the tree and the other one lives in the lower canopy
Give four examples of interactions that may occur in an ecosystem
Any 4:
Predation
Reproduction
Competition (for space, mates, food)
Mutualism
Parasitism
What is intraspecific competition? with an example
Competition within the same species. i.e. two male deer competing for mates
What is interspecific competition? with an example
Competition amongst different species.
i.e. two different predators fighting over the same food like lions and cheetahs fighting over the same antelope
How to remember the difference between interspecific and intraspecific competition?
‘Inter’specifc: like ‘international’ = meaning between different countries, like interspecific competition is between different species
What is predation? + example
When one animal, a predator, eats another animal, prey. i.e. lions eating zebras/ venus fly trap consuming flies
What is herbivory?
An animal eating a green plant 🌱
What is parasitism? Can it lead to the host’s death? + example
The relationship between two species in which one species (the parasites) lives in or on another (the host), gaining its food from it. Parasites do not normally kill the host however, high parasite population can lead to the host’s death. i.e. vampire bats and intestinal worms
What is mutualism? + example
The relationship between two or more species in which all benefit and none suffer. for example clownfish and the anemone
What is carrying capacity
The maximum population for an ecosystem to sustain
Briefly describe what an S-curve looks like
S-curves start with a very low population size but this very quickly turns into rapid exponential growth before meeting Carrying capacity and then fluctuating above and below this line
(population against time)
Why does the population experience exponential growth in an S curve
Biotic potential (which are the ideal conditions for exponential growth) allow for the population size to have enough suitable factors to grow exponentially
What factor causes the population of a species to fluctuate above and below the carrying capacity? Explain why it fluctuates because of this
-Environmental resistance. Environmental resistance means that there are shortages of biotic potential, therefore there is less food, space and other ideal factors that cause the population to slowly decrease. As the population goes below the carrying capacity there is now enough biotic potential to sustain the population and therefore to fluctuate above the carrying capacity again. This cycle repeats until the numbers end up stabilising
What is environmental resistance
Shortages of biotic potential for example food, space, mates
Why is it hard to define carrying capacity for humans
Carrying capacity is hard to define for humans because humans can immigrate and export/import food and people et cetera, constantly changing the carrying capacity
What type of organisms are S-curves used for
Complex organisms, for example rabbits
Briefly describe what a J-curve looks like
A J-curve grows exponentially and often exceeds the carrying capacity on a long time before the collapse occurs
What is the collapse in a J curve called on why does this happen
The sudden collapse is called a dieback and it is when the bacteria use up all of the nutrients/food therefore there is a collapse in the population as there are not enough factors to sustain a species
What type of organisms are J curves used for
Simpler organisms for example bacteria
What are density-dependent factors? + 3 examples
density-dependent factors are just things that change based on how many living things there are in a particular place. Predation, competition, disease
What is a food chain?
The flow of energy from one organism to the next
What is a trophic level
The position that an organism occupies in a food chain
What are Autotrophs
Organisms that makes their own food
What is the compensation point
When levels of photosynthesis equal levels of respiration (no new biomass is produced)
What are chemoautotrophs?
Organisms that make their own food using chemicals
What are primary consumers
Organisms at the second trophic level that consumer producers
What are secondary consumers
Organisms that consume primary consumers
What are Tertiary consumers
Organisms that consume secondary consumers
What are decomposers. give example
Organisms that decompose organic matter into simpler molecules. Bacteria, fungi
What are detritivores. example
Organisms that feed on detritus. earthworms
What is detritus
Dead organic matter
Why might it be better to use a food web to show ecosystem interactions
Food webs show different trophic levels, unlike food chains. In reality, organisms may eat more than one animal and may be predated by more than one predator. Food webs show all the different trophic levels they are in
Name three advantages and three disadvantages of food webs
Advantage:
-shows the direction of energy transfers
-Visual representation so is easy to read and understand
-enables prediction of the impact of loss of one organism from the food web
Disadvantages:
-no actual numbers or biomass is represented
-not all feeding relationships are shown
-Humans only seem to eat carnivores at the top of the food web but humans are omnivores
Why do you think snowy owls only appear when lemming numbers have fallen
Lemming numbers fall in the coldest time, they do not decompose in the cold temperature. Owl chicks are born and they’re now frozen lemming bodies to feed them so the numbers of snowy owls increase
What do you pyramid of numbers show
Pyramids of numbers show the number of organisms at a trophic level if the chain at one time. The length of the bar gives a measure of the relative numbers
Give two advantages and two disadvantages of pyramid of numbers
Advantage:
-simple and easy method of visualising feeding relationships and population change over time or season
– all organisms are included, regardless of size
Disadvantages:
– does not allow for juvenile or immature forms (i.e. tadpoles)
-Numbers can be too great to represent accurately
What do pyramids of biomass show?
It shows the biomass at each trophic level
What is biomass
Biomass is the quantity of dry organic material in an organism/population/trophic level/ecosystem
What is the equation for biomass
Mass of each individual X number of individuals
What are the two types of biomass, and what is the difference between them
-Dry biomass: drying out the organism to remove the water
Fresh biomass: a freshly dead organism with the water still inside
Is dry biomass or fresh biomass more accurate and why
Dry biomass is more accurate because it gets rid of the water that adds to the mass of the organism
Name one advantage and four disadvantages of pyramids of biomass
Advantage:
-overcomes the problems of pyramids of numbers because all forms are accounted for
Disadvantage:
-uses samples from populations so it is impossible to measure the biomass exactly
-organisms must be killed to measure dry mass
-time of year of data collection affects results
-each organism may accumulate different biomass over time
What is pyramid of productivity
The flow of energy of biomass through each trophic level. It shows the flow of energy over time - NOT as a snapshot in time. This is so we can see fluctuations
If a pyramid of productivity is in a pyramid shape
It means that the ecosystem is healthy as it must follow the second law of thermodynamics. There is a loss of entropy and energy to the atmosphere as energy through respiration therefore this would follow the second law of thermodynamics
name four advantages and two disadvantages of pyramids of productivity
Advantages:
-the most accurate system as it shows energy transfers and allows for the rate of production
– pyramids are not inverted
-energy from solar radiation can be added
-allows for comparison of ecosystems based on relative energy flows
Disadvantages:
-it is difficult/complex to collect energy data as the rate of biomass production over time is required
-Problem of assigning species to a particular trophic level (i.e. if Omnivorous)
What is primary productivity?
Light energy converted to chemical energy using chlorophyll in plants
What is gross primary production?
The amount of carbon fixed during photosynthesis by all producers an ecosystem
What is net primary production?
The amount of biomass that is available to the next trophic level, after accounting for the heat energy, lost as respiration
What is secondary Productivity?
the rate at which consumers convert the chemical energy in their food into their biomass.
What is net secondary productivity
the food that an animal consumes minus the faecal matter and respiration. This is what is available to the next trophic level.
NSP = GSP - respiration
Why does energy only flow through once in a system, but matter is cycled repeatedly
energy:- comes in once for different processes to occur
matter:- matter constantly changes form to be cycled throughout the system
Why does energy degrade in a system but matter does not
energy:- higher quality energy degrades to lower-quality energy, as heat is lost from respiration to lower grade energy
matter:- matter, like water, is recycled through the system, so changes form, but down not degrade
What are biogeochemical cycles
The movement and transformation of compounds from living, earth, and chemical components
Where is the majority of our carbon stored?
in the oceans
Where is the secondary store of carbon
the soil
How to humans alter the carbon cycle?
- burning of fossil fuels -> greenhouse affect
- deforestation due to urbanisation
- using limestone to create concrete -> C02 is a by-product of cement manufacture (CaC03 -> CaO)
- afforestation = increase in carbon sinks
What is the process called from dead organisms to fossil fuels/ carbonate rocks
fossilations
Give an example of a carbonate rock
limestone
Use the carbon cycle to explain what is meant by global homeostasis
The regulation of conditions in an ecosystem. In the carbon cycle, carbon is recycled throughout the system to maintain the equilibrium of conditions
Suggest how the large-scale planning of trees affects the movement of carbon in the carbon cycle
Increased afforestation = more carbon can be taken in through trees and less carbon will remain in the atmosphere
what process is this describing?
“production of methane or alcohol from the incomplete decay of organic matter”
fermentation
what process is this describing?
“Production of carbon dioxide from organic matter at high temperatures”
combustion
what process is this describing?
“Fixation of carbon dioxide in plants using energy from sunlight”
Photosynthesis
what process is this describing?
“Sedimentary rocks formed by the laying down of shells of marine organisms or by chemical precipitation”
carbonate rock formation
what process is this describing?
“Release of carbon dioxide from living organisms to produce energy for metabolic processes”
respiration
Why is nitrogen important? (5)
- important for the production of proteins and DNA
- 78% of the atmosphere = nitrogen
- Your body is 3% nitrogen in weight
- Important in the agricultural sector, where it is used as an additive in chemical fertilisers to help plants grow
- thus is important to start the food chain
Name 2 transfers and 1 transformation in the nitrogen cycle
transfers:
-cow dung falling on the ground
-nitrates are taken up by the plant
transformations:
-the transformation of organic matter into ammonium
If there is so much nitrogen in our atmosphere, then why is there not enough in our soils for plants to grow?
In our atmosphere, nitrogen is largely found as N2, which plants are unable to take up. This is because nitrogen is an inert gas. Plants need nitrogen in the form of ammonium ions or nitrates to absorb it into the plant.
what is the nitrogen cycle
the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial and marine ecosystems
what is nitrification
the process where certain bacteria in the soil convert ammonia into nitrates, which plants use to grow.
1. ammonia into nitrites
2. nitrites into nitrates
what is denitrification
the biological process where certain bacteria in the soil or water change nitrates into nitrogen gas which goes into the air
how do humans influence the nitrogen cycle (4)
- fertiliser use: farmers use nitrogen-rich fertilisers to help crops grow - wash into rivers and lakes = eutrophication
- burning fossil fuels -> cars, factories and power plants release nitrogen oxides -> climate change
- livestock farming: large amounts of nitrogen is released into the environment from animal waste
- sewage and waste: improperly treated human waste releases nitrogen compounds into the env, impacting water quality
Sadly Farmers Burn Livestock (Mnemonic to remember)
what is eutrophication?
when a body of fresh water gets enriched with nutrients (nitrates and phosphates), leading to algal blooms and increased risks of death to the ecosystem
what is the process of eutrophication
- nutrient load-up: excessive nutrients are flushed into water bodies by rainwater
- plants flourish: these pollutants cause aquatic growth of algae, duckweed and other plants
- algae blooms: this prevents sunlight from reaching other plants. The plants die and oxygen in the water is depleted
- decomposition further depletes oxygen: dead plants are broken down by bacteria, using up large amounts of oxygen in the process. This reduced oxygen for other aquatic life
- death of the ecosystem: oxygen levels reach a point where no life is possible. Fish and other organisms die
what is the equation for the efficiency of assimilation
efficiency of assimilation = (gross productivity/ food eaten) x 100
what is the equation for efficiency of biomass productivity
efficiency of biomass productivity = (net productivity/ gross productivity) x 100
what is the rough efficiency of an energy transfer
10%
what is assimilation
the absorption and digestion of food or nutrients by an organism
what are ruminant herbivores
herbivores that have 4 stomach compartments, therefore they will have higher assimilation energy
do carnivores or herbivores have a high gross productivity? why?
carnivores. This is because they eat meat and other animals. Therefore, they get more protein and fat than herbivores and can retain more energy. Therefore they have a higher gross productivity
why do pandas have very little energy
they mainly eat bamboo shoots. They are harder to digest and break down. Therefore they have less energy because bamboo has low nutritional value
what is a subsidy
Adding something into a system to get what you need out of it
if you were a crop farmer, what would you do to try to maximise your profit
-A farmer aims to maximise the net primary productivity of the organisms they grow
– this means extra energy is put into the system other than that of the Sun
– human labour, animal labour, machines use fuel to power tractors, pump water for cattle, fertilisers and other chemicals, transporting the crop etc
– all farming practices require an energy subsidy for example oxen pulling plough, humans scattering seeds)
What is an energy to yield ratio
The amount of yield you get for the amount of energy you put in
Slash-and-burn Agriculture has a ratio of 1: 30. What does this mean?
For 1J of energy you put in you are getting 30 J of yield
What is a biome + example
A collection of ecosystems sharing similar climatic conditions. for example desert, tropical rainforest, arctic tundra, marine (oceans), chaparral
What are five factors that influence the position of biomes
– Latitude
– altitude
– productivity
– ocean currents and wind
- Precipitation to evaporation ratio
How does latitude affect the position of biomes
Lat is how north or south is. The sun rays is spread further to the poles therefore the Arctic is colder and this influences the life that is there
How does altitude affect the position of biomes
higher altitudes mean lower pressure means the air becomes thinner, influencing lives there. Altitude is the height above sea level
How do you ocean currents and wind effect the position of biomes
And wind bring warm water and weather
How does the precipitation to evaporation ratio affect the position of biomes
If the precipitation to evaporation ratio is approximately one, the precipitation is about the same as evaporation meaning soil tend to be rich and fertile
What does it mean if the precipitation to evaporation ratio is greater than one
This means there is more precipitation than can be evaporated. Therefore there is more water left in this biome and the biomes that are usually found here tend to be very humid climates for example wetlands or tropical rainforests
What does it mean if the precipitation to evaporation ratio is less than one
This means that water is evaporating at a quicker rate then it has been precipitated therefore desire will have less water availability and a dry landscape for example a desert
Some scientists have hypothesised that climate change is causing biomes to shift location. Explain how the climate may be changing and the effect it may have on local wildlife (4)
(1) As climate change progresses, temperature increases and altered precipitation patterns can shift biomes to new locations. For example, areas that become warmer may transition from temperate forests to grasslands. (2) Species may be forced to migrate to new habitats that match their preferred climate. Many animals and plants might move towards higher latitudes or elevations as they try to adapt to the changing conditions. (3) As biomes shift, species that cannot adapt quickly enough may face extinction. Ecosystem disruption, habitat loss, and food scarcity further stress local wildlife. (4) Climate-induced changes such as more frequent droughts, storms, and wildfires will put additional pressure on wildlife, affecting reproductive success and survival rates.
Describe how biomass data from a named biome could be collected.
(it is a 3 mark question by try to remember all the steps)
- name a biome (rainforest)
- sample the vegetation in the biome using a large quadrat
- use stratified or random sampling to ensure all ecosystems within the biome are accounted for
- Capture and measure the wet mass of all organisms in the quadrat
- dry the organisms and calculate the dry mass
- calculate the average biomass per quadrat and extrapolate this for the whole biome
- take readings in different seasons to account for variability
State how you could determine gross secondary productivity of a zebra.
measure the mass of food that the zebra eats and measure the mass of the faecal loss;
GSP is the difference between food consumed & faecal loss
GSP = food eaten - faecal loss;
what is a nutrient
a substance that promotes growth and health in living things
what would the nutrient cycle look like for a tropical rainforest (the biomass, litter and soil)
- small litter
- large biomass
- small soil (small store of due to leaching)
state 2 processes that reduce the amount of sunlight from reaching the earths surface as light travels through the atmosphere
- scattering
- absorption
describe 2 ways in which the pyramid structure of an ecosystem may be changed by a named human activity
Deforestation (affecting biomass pyramids):
In tropical rainforests, deforestation for agriculture or urban development reduces the biomass of primary producers (trees and plants). Since these plants form the base of the pyramid, their removal causes a ripple effect, reducing the energy and biomass available to herbivores and subsequently to carnivores. This collapse leads to a narrower base in the biomass pyramid, destabilizing the entire ecosystem.
Overfishing (affecting numbers pyramids):
In marine ecosystems, overfishing depletes populations of higher trophic level species (e.g., predatory fish like tuna). This can cause an imbalance where lower trophic level species (e.g., smaller fish or plankton) proliferate due to fewer predators, distorting the pyramid of numbers. Instead of a typical broad base and narrow apex, the pyramid may flip, showing fewer predators and an overabundance of prey, which can harm biodiversity.
What is zonation
Zonation refers to changes in community along an environmental gradient, due to factors such as changes in altitude, latitude, tidal level or distance from shore (coverage by water).
What is succession
Succession is the replacement of one community by another in an area over time due to changes in biotic and abiotic variables.
Give one example of zonation
Changes in altitude – from the bottom to the peak of a mountain
Is zonation gradual or distinct
Gradual
give one example of succession
Any one from:
- Hydrosere: Succession in a body of freshwater. In this process, small lakes may disappear and be replaced by the plant communities.
- sand dunes to a woodland
- a lichen surviving on a virgin rock evolving into a forest over 100s of years
describe the process of primary succession
- Bare rock -> rock is stripped of soil cover during a glaciation
- pioneer species are the first ones to arrive (lichens, liverworts). They grow in the cracks of the bare rock that come from weathering
- over time the lichens will decay and leave behind nutrients. Mosses and herbs will grow and then small shrubs and brambles
- in the intermediate stages, the soil depth and strength starts to increase, making way for small trees and large shrubs to grow
- Climax community -> this is when the conditions are right for the most advanced species to grow ( oak and ash trees), the soil depth and strength is at its highest and the composition of the system stops changing. The conditions are viable for animals to come and there is greater secondary productivity
what are the changes in productivity from pioneer to climax communities in succession
Early Succession:
Pioneer species often exhibit rapid growth and high primary productivity due to ample light and nutrients.
Initial stages have low secondary productivity because of the limited presence of herbivores and predators.
Later Succession:
As the ecosystem matures, primary productivity stabilizes and may decrease slightly as competition for light and nutrients increases.
With more complex food webs and higher species diversity, secondary productivity increases
what does plagioclimax mean
when you deflect or stop succession
name 6 human methods of producing plagioclimax communities + brief description of how they are used to produce a plagioclimax community
- grazing - prevents the establishment of taller plants
- trampling - use livestock to produce bare ground for the germination of seeds
- mowing - removes vegetation that would have been removed by grazing
- burning - used to remove vegetation that might not be eaten by grazing animals
- coppicing - trees are cut to ground level annually depending on wildlife species -> creates new habitats for organisms -> diversity!
- pollarding - when branches are cut above the height so deer or other livestock cant eat the re-growing branches
identify two limiting factors affecting vegetation near the top of a mountain
any two from:
- lack of water
- exposure to strong winds
- thin soils
- cold temperature
what is primary succession
When plants in habits and area that had no plants before
What is secondary succession
Succession occurs where a disturbance has removed the vegetation from our place but left the soil intact for example of wildfire
Why is secondary succession faster than primary succession
In secondary succession the soil is already there so you do not need to wait for it to form
Name five differences between primary succession and secondary succession
- primary succession starts with no life where as secondary succession follows the removal of existing vegetation
- primary succession has no soil present where a secondary succession has soil present
- Primary succession is a new for example of volcanic island where our secondary succession is an old area
- Lichens and moss come in primary succession whereas in second succession seeds and roots are already present
- in primary succession to buy a mass is low in secondary succession to buy a mass is higher
Explain how the process of succession might lead to changes in the secondary and primary productivity of trophic levels (4)
- pioneer community - there are minimal plants in the system therefore primary productivity is low.
- secondary productivity is also low as there are less produces available for organisms
– intermediate community – more complex plants slowly evolve leading to an increase in primary productivity because of so depth allowing for more organisms to come therefore there is an increase in secondary productivity
– climax community –gross primary productivity is an all-time high as more plants provide habitat for more organisms increasing the gross secondary productivity
Distinguish using examples between the processes of succession and zonation (4)
– zonation is a gradual change of abiotic factors that influence the biotic factors in that zone over a distance
– one example is the change in zones from the bottom to the peak of a mountain
– succession is when a species involves over time from a pioneer to a climax community
–one example or Sand dunes to a woodland
What is an r strategist + example
Organisms that live in unpredictable and unstable environments that the need to reproduce properly is important. r strategists are less likely to live to 100% of their lifespan they produce an exponential amount of offspring and provide no parental care the population is controlled by density independent factors for example climatic events or fires. tend to be a trophic level and reach maturity early. Oysters produce 500 million offspring yearly
what is a k strategist
Organisms that live in stable environments that produce a lower amount of offspring. They give a lot of care to their offspring and us tend to live to almost 100% of their lifespan. They give birth to fewer organisms but put in lots of energy to provide more parental care. The population is controlled by density dependent factors for example competition and predation. This means that the population is dependent on the number of organisms unlike r strategists where the number of organisms doesn’t affect the population. One example great apes who produce one infant every five or six years and provide extensive parental care.
What would the population size by time graph look like for r strategists
There would be an exponential increase showing the birth of offspring followed by a vertical decrease where a lot of the offspring have died. The cycle with them repeats whether there will be an exponential increase of more organisms followed by an extremely sharp decrease where they die off
What would the population size by time graph look like for k strategists
The population size is limited by carrying capacity and is density dependent. Therefore factors such as competition and predation will cause the population to slightly fluctuate above the maximum caring capacity line
What a survivorship curve for a r strategist and a k strategist look like
On the Y axis is number of survivors in log scale (zero, 10, hundred, thousand). On the X axis is percentage of max 100% lifespan. For a r strategist there would be a gradual decreasing curve from the top of the Y axis gradually curving down to the end of the X axis. For a k strategist the curve would start at the top of the Y axis and gradually curve downwards to the end of the X axis into a vertical line (the shape of this part of the graph should resemble half a rainbow)
Explain how k strategists and r strategists are linked to succession (6)
- define succession with an example
- Define r strategist with an example
- Define k strategist with an example
what is gross secondary productivity
the total energy or biomass assimilated by consumers and is calculated by subtracting the mass of faecal loss from the mass of food consumed.
what is nitrogen fixation
the process of converting N2 into biologically available nitrogen
what does ‘fixation’ mean
converting molecules from one unusable form to another form viable for organisms
Outline how nitrifying bacteria increase soil fertility
Ammonia is converted to nitrates by nitrifying bacteria in the soil. Plants absorb nitrates from the soil and use these to build up proteins. This increases the soil fertility as it changes the conditions for plants to survive and grow
Explain how solar energy drives the nitrogen cycle
Allow photosynthesis implants to absorb the nitrates in the soil for plant growth and protein production
Evaluate one method for measuring primary productivity in a named ecosystem. (7 marks)
write method and evaluation of method
Method:
light and dark bottle for an aquatic ecosystem;
measure dissolved oxygen at start and end of experiment;
compare measurements in a transparent (with light) and opaque (without
light) bottle containing sample of water from ecosystem;
net productivity is equivalent to change in dissolved oxygen in light bottle;
gross productivity is equivalent to change in dissolved oxygen in light bottle
plus the loss of dissolved oxygen in the dark bottle (due to respiration);
measurements taken for a set period of time, eg one week;
Evaluation:
simple, easy to conduct method;
ethical method – samples can be returned to ecosystem;
difficult to isolate primary producers from consumers in ecosystem sample;
only collecting productivity for submerged subset of ecosystem;
measurements dependent upon temperature;
quality of measurements depends on precision of instruments;
