unit 4 Flashcards
define species
- a group of organisms that can interbreed to produce fertile offspring.
members of the same species have:
- similar characteristics
- different gene pools to other organisms
- a common phylogeny
define habitat
the environment in which a species normally lives or the location of a living organism.
define population
a group of organisms of the same species who live in the same area at the same time
define community
a group of interdependent organisms inhabiting the same region and interacting with each other
define ecosystem
a community of organisms and the abiotic environment where they live.
define ecology
the study of relationships between living organisms and their environment.
what is an autotroph?
- an organism that synthesizes its organic molecules from simple inorganic substances
- plants and algae are mostly autotrophic but some are not
what is a heterotroph
- an organism that obtains organic molecules from other organisms
- consumers, detritivores and saprotrophs
what is a consumer and what are the different types?
- heterotrophs that obtain their organic nutrients by ingesting living organisms
- herbivore = feeds on producers (plants)
- carnivore = feeds on other consumers (animals)
- omnivore = feeds on a combination of both
what is a detrivore?
- heterotrophs that obtain organic nutrients from detritus (non-living organic matter) by internal digestion
- e.g earthworm
what is a saprotroph
- heterotrophs that obtain organic nutrients from dead organisms by external digestion
- because saprotrophs facilitate the breakdown of organic material, they are referred to as decomposers.
- e.g bacteria and fungi
what are biotic factors?
- living things (in an ecosystem)
- e.g. plants, animals, bacteria & fungi
what are abiotic factors
- non-living things (in an ecosystem)
- e.g. temp, wind, moisture, sunlight & soil pH
what are the 3 requirements for sustainability in an ecosystem?
- nutrient availability (nutrients can be recycled indefinitely)
- detoxification of waste products
- energy availability (energy cannot be recycled = sustainability depends on continued energy supply)
what is a decomposer?
- organisms that derive energy from non-living organic matter
- detrivores & saprotrophs
what is the nutrient cycle
- autotrophs convert nutrients from inorganic to organic molecules (e.g. carbon - glucose)
- heterotrophs ingest other organisms to gain organic forms of nutrients
- saprotrophs break down organic nutrients to gain energy - in the process, release nutrients back into inorganic molecules (e.g. fungi release nitrogen as ammonia into soil)
- this ensures the continuing availability of nutrients to autotrophs
what is a mesocosm?
a biological system that contain the biotic and abiotic features of an ecosystem, but are restricted in size and/or under controlled condidtions
what is a food chain?
shows the direction of energy flow from one species to another. The arrow indicates the direction of the energy flow
what is a trophic level?
the trophic level of an organism is its position in the food chain
e.g. producers, primary consumers, secondary consumers and tertiary consumers
what is a food web?
a diagram that shows all the feeding relationships in a community with arrows which show the direction of the energy flow
what is a producer?
an organism which produces its own food through photosynthesis
how do autotrophs obtain CO2
- CO2 diffuses down the concentration gradient from the atmosphere or water into autotrophs (via stomata)
- autotrophs convert CO2 into carbon compounds (e.g. carbs) by photosynthesis
how is CO2 produced?
- cellular respiration
- methane oxidation
- combustion of biomass and fossilized organic matter
how does cellular respiration produce CO2?
- during cell respiration, water & CO2 are created as byproducts
- CO2 diffuses out of organisms into water or the atmosphere
how does methane oxidation produce CO2?
- methane is produced as a byproduct from organic matter in anaerobic conditions by methanogenic archaeans
- methanogens are found in a variety of anoxic environments (e.g. wetlands & digestive tracts of animals)
- some of the methane produced diffuses into the atmosphere or accumulates in the ground.
- methane is oxidized to carbon dioxide and water in the atmosphere.
how is peat formed
- saprotrophs partially decompose dead organic matter. - dead organic matter is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils.
- large quantities of partially composed dead organic matter build up.
- the dead organic matter is compressed to form peat.
annual fluctuations of CO2
- during summer: the rate of photosynthesis /\ and therefore atmospheric CO2 concentration \/
- during winter: plants lose their leaves and the rate of photosynthesis \/, therefore atmospheric CO2 concentration /\
what are the greenhouse gasses?
- CO2
- water vapour
- methane
- nitrogen oxides
what does the impact of a gas depend on?
- its ability to absorb longwave radiation
- its concentration in the atmosphere
how does the greenhouse effect happen?
- the incoming radiation from the sun is SW ultraviolet and visible radiation.
- some of this radiation is absorbed by the earth’s atmosphere = the warmed Earth emits LW radiation (heat).
- LW radiation is absorbed by gg that retains the heat in the atmosphere - also re-emits it back towards the earth.
- this causes the greenhouse effect and results in an /\ in average temperatures
- a rise in gg results in an /\ of the greenhouse effect which /\ the earth temperature further and this can be disastrous for the planet.
what are the causes of the greenhouse effect?
- /\ in CO2 (cause by deforestation & combustion of fossilized organic matter)
- intensified animal farming
- increased production of nitrogen oxides
what are the effects of the greenhouse effect?
- global warming
- extinction of species
- rising sea level
