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Biology HL > Topic 4 - Ecology > Flashcards

Topic 4 - Ecology Flashcards

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1
Q

species

A
  • group of organisms that can interbreed to produce fertile offspring
  • members of a species have a common gene pool
  • basic unit for classification of organisms
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2
Q

similarities between organisms in a species

A
  • similar observable physiological/morphological characteristics
  • genetically distinct from other species
  • common phylogeny
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3
Q

interspecific hybrid

A
  • offspring of interspecies mating and breeding

- hybrids are sterile, so no new species are formed

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4
Q

differing evolution pathways of species

A
  • if populations become separated, they may grow in a different environment
  • thus evolving in a different way due to adaptations
  • this could lead to speciation over time
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5
Q

speciation

A

when a new species is formed from a pre-existing one

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6
Q

autotroph

A
  • AKA producers
  • organisms capable of making their own organic molecules as a source of food
  • they synthesize organic molecules from simple inorganic substances
  • this process involves photosynthesis (drawing light energy from the sun)
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7
Q

heterotrophs

A
  • AKA consumers
  • cannot make their own food from inorganic matter
  • therefore must obtain organic molecules from other organisms
  • the only component they can synthesize from exposure to sunlight is Vit D
  • they get their energy from autotrophs or other heterotrophs
  • they can ingest organic matter that’s living or recently killed
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8
Q

detritivores

A

organisms that eat non-living organic matter (e.g. dead leaves, carcasses, faeces)

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9
Q

saprotrophs

A
  • organisms that live on or in non-living organic matter
  • they secrete digestive enzymes and absorb the products of digestion
  • some are decomposers as they break down waste material
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10
Q

community

A

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

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11
Q

interacting (ecology term)

A
  • one population feeding on another or being eaten
  • one species providing a vital substance for another
  • one species protecting another from a predator
  • one species relying on another for its habitat (e.g. parasites living in animals)
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12
Q

abiotic

A

non-living components of the environment (e.g. temp, pH, water, air, rocks)

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13
Q

biotic

A

living aspects of the environment

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14
Q

nutrient cycling

A
  • organisms must find what they need within the materials available in the environment
  • but organisms absorb those valuable materials, thus becoming unavailable to other organisms
  • so ecosystems need to recycle the carbon, nitrogen, and other elements/compounds
  • this can be done via feeding and decomposition
  • informally referred to as the “circle of life”
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15
Q

role of decomposers in nutrient cycling

A
  • decomposers break down the bodies of dead organisms
  • their digestive enzymes convert the organic matter into a more usable form for themselves and for other organisms
  • so decomposers recycle nutrients so that they become available to other organisms
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16
Q

biological significance of nitrogen

A
  • needed in nucleotides and amino acids
  • so without it, proteins and DNA cannot exist
  • thus, life would be impossible
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17
Q

nitrogen fixation

A
  • the process of trapping and transforming nitrogen in the atmosphere into useful forms (e.g. nitrates)
  • done by nitrogen-fixing bacteria
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18
Q

nitrogen cycle

A
  • nitrogen-fixing bacteria transforms nitrogen
  • some plants host these bacteria in root nodules
  • these usable nitrates are then absorbed by plant roots
  • the plants pass on those nitrates when consumed
  • the nitrogen is returned to the soil in a variety of ways (e.g. feces, urine, decomposition)
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19
Q

importance of sunlight in ecosystems

A
  • some ecosystems (e.g. deep ocean water) exist in total darkness
  • but most of Earth’s ecosystems depend on sunlight to provide energy
  • plants (producers) rely on sunlight to provide light energy in order to utilize photosynthesis
  • without sunlight, producers could not survive, and therefore entire ecosystems would collapse
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20
Q

role of photosynthesis in ecosystems

A
  • photosynthetic organisms take CO2 and convert it to energy-rich sugar
  • the addition of complex minerals allows the synthesis of more complex organic molecules (e.g. lipids, cellulose)
  • basically, light energy is being converted into chemical energy
  • organic molecules are rich in energy thanks to chemical bonds within the molecule
  • consumers can’t eat sunlight, but the light energy is converted into a consumable medium thanks to photosynthesis
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21
Q

flow of energy through a food chain

A

the process of passing energy from one organism to another via feeding

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22
Q

food chain

A

sequence showing the feeding relationships and energy flow between species

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23
Q

trophic level

A

level used to indicate how many organisms the energy has flowed through

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24
Q

sources of energy loss from one trophic level to the next

A

HEAT

  • heat is generated via cellular respiration
  • since not all energy is converted to ‘useful’ energy (ATP)
  • while it keeps mammals warm, it isn’t a reusable biological resource
  • it’s gradually lost to the environment
  • when it leaves the ecosystem it is not reusable
  • but this isn’t really a problem as the Sun is always providing more energy to the producers

INEFFICIENCY

  • only chemical energy is passed to the next trophic level
  • and only 10-20% of the chemical energy is actually passed on
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25
Q

reasons for inefficiency when passing energy up trophic levels

A
  • not all of the organism is ingested as a food source, some parts are rejected and will decay
  • not all food swallowed can be used in the body
  • some organisms die without being eaten by another organism
  • considerable heat loss due to cellular respiration
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26
Q

pyramid of energy

A

shows how much and how fast energy flows from one trophic level to the next in a community

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27
Q

pyramid of energy unit

A

kJ m^-2 yr^-1

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28
Q

trophic level limit

A
  • some food chains have 6 trophic levels but most have 4

- the no of levels is limited by the energy available in the ecosystem

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29
Q

biomass

A
  • estimate of the mass of all the organisms in that level

- expressed in units of mass but also takes area & volume into account

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30
Q

biomass unit

A

mass area^-1 time^-1

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31
Q

biological significance of carbon

A
  • so important that organic means ‘carbon is present’

- life on Earth is also referred to as carbon-based life

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32
Q

biosphere

A

all the places where life is found

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33
Q

lithosphere

A

all the places where rocks are found

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34
Q

role of autotrophs in carbon cycle

A
  • autotrophs convert atmospheric CO2 into organic energy sources
  • from glucose, many useful and important compounds (e.g. cell membranes, proteins) can be built
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35
Q

presence of carbon in aquatic ecosystems

A
  • aquatic ecosystems contain dissolved CO2
  • as CO2 from the atmosphere can be absorbed by water
  • and a product of cellular respiration is CO2
  • dissolving CO2 in water will create an acid
  • which is why carbonated water tastes acidic
36
Q

carbon dioxide cycle

A
  • CO2 is absorbed by photosynthetic autotrophs and converted into organic molecules
  • when the producers are consumed, the consumers will use those organic molecules to respire
  • this produces CO2, resulting in its release to the atmosphere
37
Q

methane in the carbon cycle

A
  • other carbon compounds can be produced by microbes (e.g. archaeans)
  • methanogens (type of archaea) respire anaerobically
  • when they metabolize food, they produce CH4 as a byproduct
38
Q

where can methane be found?

A

methanogens are common in:

  • wetlands, where marsh gas may glow mysteriously at night
  • animal digestive tracts (including humans)
39
Q

implications of the oxidation of methane

A
  • methane is the main ingredient in natural gas (a fossil fuel)
  • upon oxidation, H2O and CO2 are produced
40
Q

peat

A
  • partially decomposed plant material
  • a type of waterlogged soil
  • only certain types of vegetation can grow on its surface
  • at least 30% of its dry mass is dead organic material
  • anaerobic conditions (preventing the growth of microorganisms that would normally help decompose the organic material)
41
Q

hisostol

A
  • the soil that forms peat

- very acidic

42
Q

preparing peat to use as a fossil fuel

A
  • cut peat is dried out to reduce its high humidity
  • it’s cut into slabs/granules/blocks and moved to where its needed
  • if left in the correct conditions, partially decomposed peat can be transformed into coal
43
Q

effectiveness of peat as a fossil fuel

A
  • like all fossil fuels, it takes a long time to reform
  • therefore it’s not a renewable energy source
  • when fuel prices are high, peat can be a competitive energy source
  • so some countries try draining their wetlands
44
Q

environmental concerns with wetland draining

A
  • habitat for unique species

- pollen trapped deep in bog can give us information about the climate thousands of years ago

45
Q

formation of coal

A
  • if left in the correct conditions, partially decomposed peat can be transformed into coal over time
  • over millions of years, sediments accumulate over the peat, and their weight + pressure compresses the peat
  • sedimentation occurs until the carbon-rich compounds are both in high temps (due to being far below Earth’s surface) and under great pressure
  • the pressure and heat cause chemical transformations associated with lithification
46
Q

lithification

A

process in which molecules are compacted and rearranged

47
Q

effectiveness of coal as a fuel

A
  • coal has very long hydrocarbon chains
  • each C-H bond contains a lot of energy
  • so because the chains are so long, coal contains a lot of energy
  • this energy can be released by burning
48
Q

formation of petroleum products

A
  • carcasses don’t fully decompose at the bottom of the ocean
  • so they form layers of sediment with silt
  • in anoxic conditions they form sludge (as some parts of the organism decay while others don’t)
  • the component resistant to decay in algae and zooplankton is the lipid component
  • accumulated lipids trapped in sediments at the bottom of the ocean form kerogen
  • kerogen is rich in hydrocarbons
  • it’s transformed by pressure and heat as sediments accumulate above it and causes rearrangement of molecules
  • over millions of years, kerogen in porous sedimentary rock becomes crude oil or natural gas (if in gaseous state)
  • as these petroleum products are less dense than the rock, they tend to rise through cracks towards the surface
49
Q

anoxic conditions

A

conditions lacking oxygen

50
Q

conditions for extraction of petroleum products

A
  • they should be trapped and pooled under a non-porous rock
  • preferably one that has been bent by tectonic movement into a dome
  • this allows large quantities of gas and oil to collect in a natural reservoir
51
Q

biomass as an energy source

A
  • fresh, wet animal dung mixed with other refuse from a farm are put in a container
  • methane-producing organisms will decompose and ferment the material to produce CH4 gas
  • CH4 produces energy when undergoing a combustion reaction
  • unlike fossil fuels, biogas made in this manner won’t take millions of years to form
52
Q

biofuel production

A
  • plant material is fed to microorganisms that ferment them to produce ethanol
  • ethanol is added to gasoline
  • most cars need 75% gasoline but vehicles adapted for biofuel can use 100% ethanol as fuel
  • alternatively biodiesel can be made from a different method
  • using vegetable oil and fat
53
Q

environmental impacts of biofuels

A
  • biofuels reduce dependence on fossil fuels
  • however, burning biofuels still releases CO2
  • the difference is that the released CO2 comes from plants that absorbed the CO2
54
Q

formation of limestone in aquatic conditions

A
  • marine organisms absorb carbon to build carbonate shells
  • the carbon can be in the form of HCO- or CO2
  • coral polyps absorb HCO- and Ca+ from the seawater to build reefs
  • when combined, this forms CaCO3 (calcium carbonate)
  • other organisms also have CaCO3 shells that accumulate at the bottom of the ocean after their death
  • when those shells accumulate in sediments, they undergo lithification to form limestone
55
Q

carbon sequestration

A

the process of taking carbon out of the environment and ‘locking’ it in a substance for an extended period of time

56
Q

biosequestration

A

when carbon sequestration occurs naturally

57
Q

uses of limestone

A
  • building material

- ingredient of modern cement

58
Q

biosequestration in the formation & use of limestone

A
  • foraminifera are microorganisms that build protective CaCO3 shells
  • an accumulation of foraminifera shells can trap carbon in limestone for millions of years
  • when cement is made by humans for construction, limestone is used
  • so the carbon is released as CO2, cancelling the biosequestration
59
Q

greenhouse effect

A

planet’s ability to use its atmosphere to retain heat and keep warm even with no sunlight hitting the surface

60
Q

how the greenhouse effect works

A
  • when sunlight hits an object, a part of its light energy transforms into heat
  • heat energy (AKA infrared radiation) has longer wavelengths than energy in the form of light
  • when sunlight passes through the atmosphere, the planet’s surface radiates heat to the atmosphere
  • most of sunlight remains unconverted and go back to space
  • but for the remaining, the atmosphere is not as permeable to heat energy as it is to light energy
  • the atmosphere prevents warm air from rising through convection to dissipate heat
  • thus the temperature in the atmosphere is warmer than outside it
61
Q

cause of greenhouse effect

A
  • greenhouse effect is dependent on the atmosphere’s ability to retain heat like the glass on a greenhouse
  • greenhouse gases (GHGs) can be thought of as the glass in a greenhouse
62
Q

how greenhouse gases work

A
  • GHGs can absorb and radiate IR heat
  • they keep the atmosphere near the surface warm by absorbing heat from the warmed surface and re-radiating it in all directions
  • this includes back down to the surface
  • some heat is lost to space but most are redirected to the surface
  • the rest radiate within the atmosphere, preventing it from getting extremely cold at night
  • some gases also filter some of the more harmful radiation of the sun (e.g. UV)
63
Q

factors affecting the influence of a greenhouse gas

A
  • ability of a gas to absorb long-wave radiation

- concentration of that gas in the atmosphere

64
Q

why is CO2 a more effective greenhouse gas than CH4?

A
  • methane has greater ability to absorb radiation
  • but in the atmosphere, CH4 is short-lived (12 years)
  • this is because it can be broken down into other molecules
  • but CO2 is not very reactive so it can stay much longer (50-200 years)
  • so CO2 is much more abundant
65
Q

albedo

A
  • ability of a surface to reflect light
  • the higher the albedo, the better the reflective ability
  • light surfaces have high albedo while dark surfaces have low albedo
66
Q

climate

A

patterns of temperature and precipitation over long periods of time

67
Q

ice age

A
  • period of significant change of climate

- produced sheets of ice hundreds of meters thick

68
Q

factors contributing to global temperature change

A
  • volcanic activity
  • particles suspended in the air
  • quantity of radiation from the sun
  • position of the continents
  • oscillations in ocean currents
69
Q

proxy data

A

measurements used in place of data that cannot be directly measured

70
Q

application of proxy data in researching climates of the past

A
  • some foraminifera microfossils can reveal temperature changes via slight changes in the chemical composition of their shells
  • layers in thick ice sheets can extracted as ice cores (cylinder-shaped samples of ice) to study the substances trapped between the layers
  • a lot of info can be gleaned from them
  • for example, the frequency of different isotopes can indicate the temperature of their time
  • oxygen is commonly found as O-16 but during glaciations, O-18 is more common in oceans while O-16 is more common in glaciers
71
Q

CO2 conc trends over time

A

ever since the Industrial Revolution, human activities have caused CO2 levels to increase significantly (more than 35% compared to pre-industrial revolution)

72
Q

effect of human activity on greenhouse gas concentrations

A
  • without interference, the concentration of greenhouse gases in the atmosphere are low
  • this prevents excessive heat retention
  • but ever since the industrial revolution, concentrations have risen past natural levels
73
Q

human activities that contribute to carbon emissions

A
  • greatest contributor to human carbon emissions is fossil fuel-based transport
  • deforestation
  • heating homes by burning fossil fuels
  • maintaining a diet high in meat (the meat industry is heavily reliant on fossil fuels)
  • etc
74
Q

human activities that produce oxides of nitrogen (NOx)

A
  • burning fossil fuels
  • using catalytic converters in exhaust systems
  • using organic and commercial fertilizers
  • industrial processes (e.g. the production of nitric acid)
75
Q

factors coral polyps are sensitive to

A
  • temperature
  • pH (acidity)
  • water depth
76
Q

how do rising CO2 concentrations affect polyps?

A
  • increased CO2 concentration = increased dissolved CO2 in oceans = pH of seawater lowered
  • ocean acidification leads to the death of polyps and algae
  • when they die, the coral reefs turn white
77
Q

bleaching

A
  • when a coral reef turns from multicolored to white

- due to the death of polyps/algae

78
Q

impact of polyp deaths on the ecosystem

A
  • when bleaching occurs, the coral reef is unable to support the ecosystem
  • thus the organisms that live in reefs for food and shelter have to move elsewhere
79
Q

radiative forcing

A

difference between the energy arriving at the surface and the energy lost in space

80
Q

Challenge from critic: “Climate change due to human activity is a theory, not a fact” – response?

A
  • clear evidence of world temperatures rising since the Industrial Revolution
  • predictions of extreme weather events, record temperatures, and receding glaciers are coming true
  • IPCC finding: “largest contribution to total radiative forcing was caused by the increase in the concentration of atmospheric CO2 since 1750”
81
Q

Challenge from critic: “There is disagreement in the scientific community about human-induced climate change; many scientists don’t think we are accountable” – response?

A
  • the vast majority of publications from climatologists confirm climate change
  • the dissenting scientists quoted by critics are often not climatologists
  • scientists are mostly in disagreement over the degree of accountability we have regarding climate change
82
Q

Challenge from critic: “Your model predicted a higher temperature increase than the change in reality” – response?

A
  • climatology is complex
  • human activities produce particles that may remain suspended in air
  • some of these aerosols can diffuse sunlight
  • this causes a reduction in the amount of short-wave radiation reaching the surface
  • less solar radiation = fewer rays to be converted into IR waves = lower temperatures
  • this phenomenon cancels out some of the predicted warming
83
Q

Challenge from critic: “There have been huge fluctuations in climate in the past and there may be a natural explanation for this” – response?

A
  • it’s true that climate has fluctuated in the past
  • but these changes occurred over millions of years
  • the changes now are happening on a scale of decades
  • the speed and magnitude of the increases in temperature and CO2 concentration are unprecedented
  • the sun output can’t explain global warming, as the recent hottest years on record occurred during low-output phases
84
Q

Challenge from critic: “If we’re held accountable for CO2 concentrations, we should reduce CO2 emissions, which would result in a severe negative economic effect” – response?

A
  • the alternative will have a delayed, but greater, economic cost
  • as the introduction of higher concentrations of greenhouse gases would exacerbate the patterns of climate change
  • and the cost of fixing these new problems would be astronomical
85
Q

How does climate change help identify issues with science?

A
  • the existence of critics is a good thing, because errors and misinterpretations of data may occur when people read publications, thus encouraging scientists to be better communicators
  • IPCC reports are filled with statements that denote uncertainty (e.g. likely, probably) – this is because scientists don’t fully understand their field of study and while they gain further insights, they can still be wrong
  • climate change deniers are frequently accused of ‘cherry picking’ (a form of confirmation bias in which one ignores evidence that doesn’t support their arguments). on the flip side, scientists may be subject to the same.
  • scientists may acquire their funding from companies that are climate change deniers, or vice versa. they may be influenced to look for evidence that aligns with the interests of their sponsors. thus it is important to double-check where the data interpretations are coming from

Biology HL (12 decks)

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