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Biology IB HL > Ecology > Flashcards

Ecology Flashcards

1
Q

habitat

A

the environment in which a species normally lives

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2
Q

population

A

a group of organisms of the same species who live in the same area at the same time

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3
Q

community

A

a group of populations living and interacting with each other in the same area

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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
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5
Q

ecology

A

the study of relationships between living organisms and their environment

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6
Q

autotrophs

A

organism that synthesises its organic molecules from simple inorganic substances

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7
Q

heterotrophs

A

an organism that obtains organic molecules from other organisms

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8
Q

consumers

A

an organism that ingests organic matter

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9
Q

detritivore

A

an organism that ingests non-living organic matter (decomposer)

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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

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11
Q

food chain

A

a representation of relationships between organisms based on their diet (not including detritivores)

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12
Q

food web

A

diagram that shows how food chains are links together to form complex feeding relationships

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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)
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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)

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15
Q

most important energy source

A

the sun (light energy)

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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
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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
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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)
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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

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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
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21
Q

species

A

a group of organisms that can interbreed and produce fertile offspring

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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
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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
Q

relationship between rises in concentration of atmospheric CO2, methane, and nitrogen oxides with enhanced greenhouse effect

A
  • 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
Q

difference between greenhouse effect and enhanced GH effect

A
  • 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
Q

precautionary principle

A

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
Q

burden of proof

A

those making claims must prove with evidence that their claim is true

29
Q

general effects of climate change due to enhanced GH effect

A
  • 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
Q

actions that may combat enhanced GH effects

A
  • 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
Q

consequences of global temp rise on arctic ecosystems

A
  • 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
Q

factors affecting sustainability of ecosystems

A
  • nutrient availability
  • detoxification of waste products
  • energy availability
33
Q

Carbon fixation

A
  • autotrophs absorb and convert CO2 into carbon compounds

- this reduces the CO2 conc in the atmosphere

34
Q

Carbon dioxide in solutions

A
  • 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
Q

absorption of CO2 by autotrophs

A
  • 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
Q

CO2 and cell respiration

A
  • waste produce of aerobic cell respiration

- occurs in non-photosynthetic cells in producers, animal cells, and saprotrophs

37
Q

methanogenesis

A
  • the production of methane from organic matter in anaerobic conditions
  • produced by 3 groups of anaerobic prokaryotes
38
Q

methanogenesis process

A
  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
  2. methanogenic archaea produces methane from acetate, hydrogen, and CO2
39
Q

areas where methanogenesis may occur

A

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
Q

ruminant mammals

A

herbivorous mammals that eat quickly and later regurgitate their food to chew it more slowly

41
Q

archaeans

A

single-celled microorganisms that generally thrive under extreme conditions

42
Q

oxidation of methane

A
  • 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
Q

peat formation

A
  • 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
Q

fossilised organic matter

A
  • 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
Q

formation of coal

A
  • formed when peat deposits are buried under other organic sediments
  • peat is compressed and heated and gradually turns into coal
46
Q

formation of oil/natural gas

A
  • 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
Q

formation of CO2

A
  • combustion of biomass and fossilised organic matter

- cell respiration

48
Q

fossilisation in production of limestone

A
  • 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
Q

formation of water vapour

A
  • evaporation from oceans

- transpiration in plants

50
Q

removal of CO2 from atmosphere

A
  • photosynthesis

- dissolving in oceans

51
Q

removal of water vapour from atmosphere

A
  • rainfall

- snow

52
Q

how to assess the impact of a greenhouse gas

A
  • ability of the gas to absorb long wave radiation

- conc of the gas in the atmosphere

53
Q

formation of methane

A
  • 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
Q

formation of nitrous oxide

A
  • released naturally by bacteria

- vehicle exhausts

55
Q

phenomenon of greenhouse gases

A
  • 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

Biology IB HL (5 decks)

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