Ecosystems Flashcards
What is an ecosystem?
A community of living organisms and abiotic components in a specific habitat, which interact. They are dynamic.
What is a habitat?
The area in which organisms live.
What is a population?
A group of organisms of the same species living in a particular area.
What is a community?
The populations of different species that live in the same area at the same time.
What does it mean that ecosystems are dynamic?
Any small change in either abiotic or biotic factors will affect the other.
Population sizes change as the community of organisms interact with each other and their physical environment.
What is the niche of a species?
The role that the species plays within its ecosystem.
It is impossible for two species to occupy exactly the same niche within an ecosystem.
What could be included in the description of a species’ niche?
What it feeds on, its habitat, its life cycle, what is excretes, how it reproduces….
How do matter and energy move through ecosystems?
Matter is constantly recycled within an ecosystem.
Energy flows through the ecosystem.
What are biotic factors?
Living factors that determine conditions for the distribution and abundance of organisms.
e.g: predation, disease, food supply…
What are abiotic factors?
Non-living factors that determine conditions for the distribution and abundance of organisms.
What are climactic abiotic factors? (4)
Light intensity
Temperature
Water availability
Oxygen availability
What are edaphic factors?
Abiotic factors to do with the soil, such as particle size, and nutrient content.
What are topographic factors?
Abiotic factors to do with the shape of the land.
e.g: altitude, slope aspect.
What is a trophic level?
Organisms that share the same function in the food chain.
What is biomass?
The total mass of living material at a certain trophic level, usually measured after drying out an organism to give “dry mass”.
Why is biomass often measured in kgm^-2?
To give the biomass of a trophic level for an area of land.
Which trophic level has the most biomass and why?
Producers.
There are a very large number of individuals, energy is poorly transferred to higher trophic levels.
How can you calculate the energy of a biomass?
Burn the organism in a calorimeter. (uses temperature change of water to calculate the released energy)
Why are the units for measuring energy at a trophic level kJm^-2yr^-1?
Shows the energy of a trophic level across an area of land.
Per year, to allow for changes in photosynthetic production and consumer feeding patterns throughout the year.
What is meant by the efficiency of energy transfer?
What percentage of an organism’s biomass is incorporated into an organism which eats them.
How is the efficiency of energy transfer calculated?
energy available after transfer divided by the energy available before transfer. (times 100)
How does energy change as you move up the trophic levels?
Energy available is always decreasing, as energy is lost at every trophic level.
What is net primary productivity? (NPP)
The energy in plants available to consumers.
NPP=GPP-energy used by producers in respiration
What is gross primary productivity? (GPP)
The energy from sunlight incorporated into producers.
How is energy lost at the primary producer level? (4)
Most light is not incident on the surface of leaves.
Most light is not absorbed by photosynthetic pigments (may not be correct wavelength).
Photosynthetic reactions require a lot of energy.
Other abiotic factors can limit photosynthesis such as water availability.
How is energy lost at the consumer level?
Energy lost as heat due to respiration.
Energy lost as parts of plants/animals are not digested and excreted.
Consumers do not eat the whole of the plant/animal.
