Ecology Flashcards
(55 cards)
1
Q
habitat
A
the environment in which a species normally lives
2
Q
population
A
a group of organisms of the same species who live in the same area at the same time
3
Q
community
A
a group of populations living and interacting with each other in the same area
4
Q
ecosystem
A
- a community and its abiotic environment
- a stable and settled unit of nature consisting of a community of organisms interacting with each other and with their surrounding environment
5
Q
ecology
A
the study of relationships between living organisms and their environment
6
Q
autotrophs
A
organism that synthesises its organic molecules from simple inorganic substances
7
Q
heterotrophs
A
an organism that obtains organic molecules from other organisms
8
Q
consumers
A
an organism that ingests organic matter
9
Q
detritivore
A
an organism that ingests non-living organic matter (decomposer)
10
Q
saprotroph
A
an organism that lives in or on non-living organic matter, secreting digestive enzymes into it and absorbing products of digestion
11
Q
food chain
A
a representation of relationships between organisms based on their diet (not including detritivores)
12
Q
food web
A
diagram that shows how food chains are links together to form complex feeding relationships
13
Q
advantages of food web
A
- shows complex interactions between species in a community/ecosystem
- shows more than one producer supporting the economy
- shows that a single consumer may have a number of different food sources (vice versa for producers)
14
Q
trophic level
A
defines the feeding relationship of the organism to other organisms in a food chain (in a food web an organism can have multiple trophic levels)
15
Q
most important energy source
A
the sun (light energy)
16
Q
explain the energy flow in a food chain
A
- photosynthesis converts light into energy
- not all solar energy will be absorbed by chlorophyll so they won’t all be trapped
- energy loss can occur due to respiration or in undigested food
- all energy will ultimately be lost as heat
17
Q
problem with energy transfer from one trophic level to another
A
- inefficient transfer (only 10-20% of the energy on one trophic level is assimilated by the next level)
- in extreme environments, the initial trapping of energy by producers are low so the food chains are much shorter
- organisms on higher trophic levels are more prone to extinction due to reliance on organisms on lower levels
- any decrease in the population of an organism can cause a chain reaction
18
Q
why are the shapes of pyramids of energy like they are?
A
- a pyramid of energy shows the flow of energy from one trophic level to another (unit: kJ/m2 yr)
- initial solar energy is not shown
- narrowing shape shows gradual loss of energy as you move up the food chain
- scale of diagram is written at the base of the pyramid (energy/area/time)
19
Q
energy flow in ecosystem
A
- at every trophic level, energy is lost as heat
- narrowing of energy pyramid shows that all energy is eventually radiated as heat
20
Q
matter cycles in ecosystems
A
- new matter is not created, nor is it lost the way energy is
- producers take organic molecules and convert them into organic compounds (helping them to be recycled and reused)
- consumers take the organic matter
- decompose recycle organic molecules found in dead organisms
- the process serves many functions including soul formation, reduction of high energy carbon compounds, and recycling nutrients stored in organic molecules
- mineral elements are absorbed by plants as ions
- the cycling process is called biogeochemical cycles
21
Q
species
A
a group of organisms that can interbreed and produce fertile offspring
22
Q
describe decomposition
A
- saprotrophic bacteria and fungi secrete extra-cellular digestive enzymes onto the dead organism
- the enzymes hydrolyse the biological molecules the dead organism is made up of
- the hydrolysed molecules are soluble and are absorbed by the fungi/bacteria
- organic molecules are oxidised, releasing CO2 back, and nitrogen in the form of nitrate/nitrite/ammonium
23
Q
Carbon cycle processes
A
Carbon can be found in 4 pools (biosphere, oceans, atmosphere, and sediments) and it moves between these pools through a variety of biological, geochemical, or industrial processes
- photosynthesis
- respiration
- feeding
- fossilisation
- combustion
24
Q
analyse changes in concentration of atmospheric CO2
A
- trends in atmospheric gases are studied as indicators of climate change
- CO2 is released unevenly around the world (partly due to vegetation distribution)
- base trend is increase in atmospheric CO2 levels
- bubbles of atmospheric gases trapped in ancient ice cores are analysed to determine CO2 levels
- temp can be determined from the ratio of O16 to O18
- concluded clear correlation between atmospheric CO2 and temp
25
relationship between rises in concentration of atmospheric CO2, methane, and nitrogen oxides with enhanced greenhouse effect
- gas molecules in atmosphere with 3+ atoms can capture outgoing infrared energy, scattering it and retaining it as heat
- average global temp will rise
- enhanced greenhouse effect is predicted to cause global climate changes
26
difference between greenhouse effect and enhanced GH effect
- GH effect is a natural phenomenon creating moderate temps on Earth to which life has adapted
- enhanced GH effect is the idea that human activity is increasing the levels of greenhouse gases, leading to increased global temps and climate change
27
precautionary principle
if the effect of a human-induced change would be very large/catastrophic, those responsible for the change must prove it won't be harmful before proceeding
28
burden of proof
those making claims must prove with evidence that their claim is true
29
general effects of climate change due to enhanced GH effect
- increased frequency and intensity of droughts
- flooding (due to higher temps causing expansion, increased rainfall, increased snow melts, rising sea level)
- permanent flooding of lands used for habitation/agriculture
- increased disease (warmer temps allow pathogens to flourish)
- more extreme weather
- more extreme temp variation all over the world
- loss of biodiversity as organisms cannot adapt
30
actions that may combat enhanced GH effects
- conservation of fossil fuels
- development of nuclear power/renewable power sources
- using biofuels to decay organic matter and photosynthesis products
- insulating homes better to reduce heating/cooling
- stop deforestation in tropical regions
31
consequences of global temp rise on arctic ecosystems
- microorganisms causing decay of accumulated detritus (which was released from its permafrost state) lead to huge releases of greenhouse gases
- more areas with soil rich in humus are formed, so more plants appear and replace ice, snow, and tundra; a wider range of biodiversity is apparent
- temporarily leads to extensive flooding of surrounding lowlands
- increased presence of pathogens due to expanded range of organisms
32
factors affecting sustainability of ecosystems
- nutrient availability
- detoxification of waste products
- energy availability
33
Carbon fixation
- autotrophs absorb and convert CO2 into carbon compounds
| - this reduces the CO2 conc in the atmosphere
34
Carbon dioxide in solutions
- CO2 is soluble in water
- its present as a dissolved gas or combined with water to form carbonic acid (H2CO3)
- carbonic acid can dissociate to form H+ and HCO3- (hydrogen carbonate)
- dissolved CO2 and HCO3- are absorbed by aquatic autotrophs
35
absorption of CO2 by autotrophs
- Carbon fixation
- reduces CO2 levels both in atmosphere and in the organisms
- sets up conc gradient between cells and in the air/water around
- this ensures flow of CO2 into the plant
- in land plants this occurs through the stomata
- in aquatic plants the entire surface of the leaves and stems is permeable to CO2 so diffusion occurs throughout
36
CO2 and cell respiration
- waste produce of aerobic cell respiration
| - occurs in non-photosynthetic cells in producers, animal cells, and saprotrophs
37
methanogenesis
- the production of methane from organic matter in anaerobic conditions
- produced by 3 groups of anaerobic prokaryotes
38
methanogenesis process
1. bacteria x converts organic matter into a mixture of organic acids, alcohol, hydrogen, and CO2
2 bacteria y uses organic acids and alcohol to produce acetate, hydrogen, and CO2
3. methanogenic archaea produces methane from acetate, hydrogen, and CO2
39
areas where methanogenesis may occur
anaerobic environments
- mud in lake beds and on shores
- swamps/mangrove forests/wetlands where soil/peat is waterlogged
- guts of termites and ruminant mammals
- landfill sites where organic matter is in buried wastes
40
ruminant mammals
herbivorous mammals that eat quickly and later regurgitate their food to chew it more slowly
41
archaeans
single-celled microorganisms that generally thrive under extreme conditions
42
oxidation of methane
- molecules of methane are naturally oxidised in the stratosphere
- they form CO2 and H2O
- monoatomic oxygen (O) and highly reactive hydroxyl radicals (OH•) are involved in methane oxidation
43
peat formation
- in most souls all organic matter is eventually digested by saprotrophs
- saprotrophs respire aerobically
- peat forms when organic matter isn't fully decomposed due to anaerobic conditions in waterlogged soil
- peat is a dark brown acidic material
44
fossilised organic matter
- partially decomposed organic matter is converted into oil/gas in porous rocks, or into coal (fossil fuels)
- carbon and some carbon compounds are chemically stable and can remain unchanged for millions of years
45
formation of coal
- formed when peat deposits are buried under other organic sediments
- peat is compressed and heated and gradually turns into coal
46
formation of oil/natural gas
- formed in mud at the bottom of seas and lakes
- usually under anaerobic conditions (resulting in incomplete decomposition)
- the partially decomposed matter becomes compressed and heated, resulting in chemical changes
47
formation of CO2
- combustion of biomass and fossilised organic matter
| - cell respiration
48
fossilisation in production of limestone
- animals such as reef-building corals and molluscs have parts made of calcium carbonate that can be fossilised in limestone
- their soft parts generally decompose quickly
- in acidic conditions the CaCO3 dissolves but in neutral/alkaline conditions it is deposited on the sea bed
- this results in limestone
49
formation of water vapour
- evaporation from oceans
| - transpiration in plants
50
removal of CO2 from atmosphere
- photosynthesis
| - dissolving in oceans
51
removal of water vapour from atmosphere
- rainfall
| - snow
52
how to assess the impact of a greenhouse gas
- ability of the gas to absorb long wave radiation
| - conc of the gas in the atmosphere
53
formation of methane
- emitted from wetlands and other waterlogged habitats and landfill (if organic wastes have been dumped there)
- released during extraction of fossil fuels and melting ice in polar regions
54
formation of nitrous oxide
- released naturally by bacteria
| - vehicle exhausts
55
phenomenon of greenhouse gases
- greenhouse gases reabsorb longer-wave radiation, retaining heat in the atmosphere
- 25-30% of short-wave rad (mostly UV light) is absorbed before reaching earth's surface
- 70-75% of solar rad reaches the earth's surface and most is converted to heat
- most of the rad re-emitted by Earth is reabsorbed before it passes out to space (between 70-85%)
- final effect: global warming
