SB9 Ecosystems Flashcards
Define ecosystem
The collection of organisms in an area along with all of its environmental factors
–> including both biotic and abiotic factors
Define community
Groups of different species living together and interacting
Define population
Group of organisms of the same species, living at the same place at the same time
Define habitat
Place where an organism lives
Define interdependence
Organisms in an area need each other for resources, such as food. If you remove on species, it can affect the whole community
Define biotic factors
Includes all living factors such as plants and animals
Define abiotic factors
Includes all non living components, such as light intensity or soil moisture
Describe the levels of organisation within an ecosystem
- Producers
- Primary consumer
- Secondary consumer
- Teritary consumer
What is the role of a producer within a food chain?
Organisms that usually produce their own food, such as plants and algae, which photosynthesis
What is the role of a primary consumer in a food chain?
- herbivores
- eat the producers
What is the role of the secondary consumers?
- carnivores
- consume the primary consumers
What is the role of the teritary consumer?
- carnivores
- top of the food chain
- eat secondary consumers
How does temperature affect a community of plants?
Affects rate of photosynthesis
How does light intensity affect a community of plants?
As light intensity increases, plant photosynthesis increases, which increases its growth
How do moisture levels affect a community?
Plants and animals need water to survive
How do we calculate the total number of organisms in a sample?
total number of organisms in a sample x (total area pf study/ total area of quadrats)
What two methods can we use for sampling?
- Belt transacts
- Quadrats
Why must quadrats be laid randomly?
To avoid sampling bias
What are quadrats?
Square frames which are used in sampling
Describe how we can estimate the number of 3-leaf clovers in a 10m by 10m field using quadrats
- Divide the field into 100 even squares and use a random number generator to randomly select a single square
- Take a 1m x 1m quadrat and place it on the square
- Count the number of clovers in that square
- Repeat this again 4 times and take an average of the five samples
- Multiply the average by 100 to estimate the number of clovers in a field
Define transacts
A line along which samples are usually taken
Describe how to carry out a belt transact
- Lay out a measuring tape across the sample area
- Place quadrats at regular intervals along the tape and record the abundance of your chosen component
What biotic factors can species abundance be influenced by?
- competition
- predator prey relationships
- interactions with other organisms within the food chain or the food web
What abiotic factors can species abundance be influenced by?
- Light intensity
- Mineral availability
- Water availability
- pH
- Temperature
- Salinity
What are the limitations of using quadrats? State the problems and their relative solutions
- easy to miss individual organisms
ans: use a pencil and carefully move other organisms out of the way - identifying species can be tricky
ans: use a species identification guide
What is the effect of competition on an ecosystem?
If one species is better adapted to the environment as compared to another, it will outcompete the weaker species in terms of food,resulting in lesser numbers of the weaker species which are insufficient to breed
What is a stable community?
One where all the species and environmental factors are in balance, so population size remains roughly constant
Define parisitism
Organism feeds off a host and causes harm to it
Define mutualism
Organisms that live together because they can both benefit off of each other
How are parasites dependant on their hosts?
Dependant on their hosts for resources such as food, shelter and a suitable place to reproduce
State an example of a parasitic relationship
Flees on a dog
State an example of a mutualistic relationship
Bees and flowers
bees get food, and flowers get pollination
Define biodiversity
Range and variety of different species in a given area
What are the advantages of high biodiversity?
- ensures the stability of ecosystems by reducing the dependance of one species on another for food, shelter and maintenance of physical environment
- populations will be more resilient to sudden environmental impacts and diseases
What do pyramids of biomass represent?
Relative biomass at each trophic level
What are trophic levels used to describe?
Feeding relationships between organisms
What does a food chain show?
Transfer of energy from one organism to the next
Define biomass
A measure of the total mass of living material in each trophic level
Why does the amount of consumers decrease as you travel up the food chain?
Since the biomass reduces each time, it is more common to find less consumers, because they require large amounts of food
What is an inconsistency as represented on a food chain?
Often times, consumers do not only have just one food source
Define indigenous species
A species that is native to a certain area
How do we calculate the efficiency of biomass transfers?
(biomass transferred to biomass/total energy supplied to organisms) x 100
Why is introducing a non indigenous species to an area a problem?
- it may compete with its indigenous counterpart for food, water or space
- would introduce a new competitor into the food chain
- they may bring diseases that the local population isn’t immune against
Why are fish farms used?
A way of raising a large amount of fish in a small space for human consumption
What are the effects of fish farms on biodiversity?
- predators may be attracted to the fish and may become caught up in nets whilst trying to access the fish
- diseases can spread easily, to both the fishes in the farm, as well as any species living outside the farm
- build up of excretion means that the toxic chemicals released stay in contact with the fish
Describe eutrophication
- Fertilisers are added, causing the rapid growth of algae
- The algal bloom blocks sunlight so water plants at the bottom begin to die
- As water plants and algae begin to die in larger numbers, this causes the growth and increase in bacteria
- Therefore leading to a lack of oxygen
- Causing the suffocation of species
Define eutrophication
The process by which a water body becomes excessively enriched with nutrients, leading to the growth of plant life
Define indicator species
Organisms that are particularly sensitive to certain changes in the environment, so much so that their presence indicates a certain environmental change
What are indicator species used to detect?
- water pollution
- air pollution
What does the presence of lichen indicate?
polluted air
What does the presence of blackspot fungus indicate?
Low levels of air pollution
What two indicator species are present in clean water?
freshwater shrimps and stonefly
What two indicator species are present in polluted water?
bloodworms and sludgeworms
What are the potential disadvantages of using an indicator species?
- can’t provide a numerical value of the amount of pollution
- presence or absence of substances can be affected by other factors as well
What are the advantages of using an indicator species?
- cheap
- natural
What are the benefits of maintaining biodiversity?
- easier to recover from natural disasters
- plants and animals are used for food and medicine
- climate change
- provides jobs
How are humans maintaining biodiversity?
- breeding programs
- protected or conservation areas
- seed banks
- reduction of deforestation and carbon dioxide production
- recycling
Define food security
Having enough food to feed a population
How does the increasing human population affect food security?
- more food needed so everyone can eat
- not enough land to produce it
How does the increasing proportion of meat in the human diet affect food security?
Less food produced per land area as animal farming needs more land and other resources as compared to plants
How does the introduction of new pests and pathogens of crops and farm animals affect food security?
Infections will reduce the amount of food produced
How does the increased use of chemicals to maximise the amount of food produced affect food security?
Pollution, eutrophication etc increase the damage to the wildlife and the environment
How does the increased use of farmland for biofuels affect food security?
Less farmland available for growing crops
What does sustainable farming preach?
Making enough food to sustain the current population without using resources faster than they can be renewed
