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biology > c1.5 - population size + ecosystems > Flashcards

c1.5 - population size + ecosystems Flashcards

1
Q

ecology

A

study of the relationships among organisms and their environment

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2
Q

ecosystem

A
  • community of organisms (biotic) + non-living (abiotic) components of an area and their interactions
  • vary from very large, e.g biome, to very small, e.g: microhabitat
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3
Q

biotic + abiotic factors, give examples

A

biotic - living features of an ecosystem, e.g: predators, disease, breeding
abiotic - non living features of an ecosystem, e.g: light, temp, oxygen

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4
Q

community

A

all of the populations of different species living together in a habitat

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5
Q

what is a habitat

A

region where an organism normally lives

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6
Q

population

A

all organisms of same species living with one another in a habitat at the same time

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7
Q

niche

A

describes how an organism fits into an ecosystem + it’s role in that environemt

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8
Q

what do population numbers depend on

A
  • birth rate
  • death rate
  • immigration
  • emigration
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9
Q

birth rate + death rate

A

birth rate - number of offspring born per thousand of population year
death rate - number of deaths per thousand of population per year

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10
Q

immigration

A

number of individuals entering a region per thousand of population per year

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11
Q

emigration

A

number of individuals leaving a region per thousand of population per year

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12
Q

when do population sizes increases

A

birth and immigrants > deaths and emigrants

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13
Q

when do population sizes decrease

A

deaths and emigrants > births and immigrants

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14
Q

phases of population growth

A

lag phase- period of slow pop growth
log phase - period of rapid exponential pop growth in which birth rate exceeds death rate
stationary phase - period of stability in which pop numbers generally remain constant

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15
Q

carrying capacity

A
  • max pop size that can be supported by an ecosystem over extended periods of time
  • varies depending on biotic + abiotic factors
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16
Q

competition

A
  • when diff organisms compete for the same resources (e.g: light, water, mates, territory) in an ecosystem
  • limits pop sizes
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17
Q

density dependent + density-independent factors, give examples

A

density dependent - factors whose effects on pop size differ w/ pop density, e.g: completion, predation, disease
density independent- factors that have an effect on the whole population regardless of population density, e.g: climate

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18
Q

abundance

A

number of individuals per species in a specific area at any given time

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19
Q

distribution

A

spread of living organisms in an ecosystem

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20
Q

sampling

A

selecting a group of individuals that will represent the whole target. population
allows us to measure distribution and abundance of organisms

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21
Q

methods of assessing abundance + distribution or organisms

A

quadrats - square frames placed at random in areas to be investigated
transects - line/belt that runs across area to be investigated

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22
Q

diff ways abundance can be quantified

A
  • percentage cover
  • percentage frequency
    x density
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23
Q

random sampling

A

sampling technique used to avoid bias,
e.g: creating a square grid + generation random coordinates

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24
Q

systematic sampling

A
  • sampling technique used to determine abundance + distribution of organism along an area at periodic intervals!
    e.g: along. belt transect
  • commonly used in ecosystems where some form of gradual change occurs
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25
Q

source of energy for ecosystems

A

light energy (other than ecosystems that rely on chemosynthesis)

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26
Q

trophic level

A

position organism holds in a food chain, food web, pyramid of numbers or pyramid. of biomass

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27
Q

biomass, how is it transferred, how is it measured

A
  • total weight of living matter in a certain area, transferred up trophic levels through consumption
    x measured in terms of mass of carbon, or dry mass of tissue
28
Q

formula for efficiency of biomass transfer

A

efficiency = biomass transferred
————————— x 100
biomass intake

29
Q

why is some energy never taken in at each trophic level

A
  • some parts of food not consumed
  • some parts of food indigestible
  • plants can’t use all light energy as some is wrong wavelength
30
Q

why is some energy lost at each trophic level

A

respiration, lost as heat

31
Q

pyramid of biomass

A

table of the dry mass of living material at each trophic level of a food chain
forms shape of a pyramid

32
Q

net + gross primary productivity

A

gpp - rate of chemical energy fixture during photosynthesis by all producers in an ecosystem, measured in kJ m ^-2 year ^-1
npp - amount of chemical energy available to heterotrophs in an ecosystem

33
Q

how is npp calculated

A

subtracting chemical energy generated in respiration (R) from gpp
npp = gpp - R

34
Q

primary succession

A

area previously devoid of live colonised by pioneer species

35
Q

pioneer species

A

species that can survive + colonies bare rock or sand,
e.g: lichens

36
Q

process of primary succession

A
  • pioneer species colonies area
  • die, decompose, and add nutrients to ground
  • over time, allows more complex organisms to survive
37
Q

seres

A

various intermediate stages in succession progressing towards a climax community

38
Q

secondary succession

A

type of succession in which a habitat is re-colonised after a disturbance

39
Q

climax community, how is it reached

A
  • final stage of succession, where ecosystem is balanced and stable (shows very little change over time)
  • reached when soil is rich enough to support large trees or shrubs + the environment is no longer changing
  • only a few dominant plant + animals species present depending on climate
40
Q

how does succession affect species diversity + stability of a community

A

succession increases species diversity + stability of the community

41
Q

examples of organisms that play an important role in decay

A

detrivores - feed on dead organic matter
saprotrophs - feed by extracellular digestion

42
Q

extracellular digestion by saprotrophs

A

release enzymes which catalyse the breakdown of dead plant + animal material into simpler organic matter

43
Q

carbon cycle

A

cycle through which carbon (in form of CO2) moves between living organisms + the environment, involving respiration, photosynthesis + combustion

44
Q

stages of carbon cycle

A
  1. photosynthesising plants remove co2 from atmosphere
  2. eating passes carbon compounds along food chain
  3. respiration in plants + animals returns co2 to atmosphere
  4. organisms dies + decompose, saprotrophs break down dead material + release co2 via respiration
  5. combustion of materials (e.g: wood, fossil fuels) releases co2
45
Q

global warming

A

gradual rise in average temp of earth due to increasing atmospheric levels of co2 + methane gas

46
Q

greenhouse effect

A

increase of global temps caused by trapping of solar heat by gases in atmosphere

47
Q

how might global warming affect the natural world

A
  • temp, rainfall, light level etc. all affect survival
    habitats may be destroyed by deforestation or flooding
  • species may need to change habitat, or face extinction
48
Q

nitrogen cycle

A

cycles through which nitrogen moves between living organisms + the environment, involving ammonification, nitrification, nitrogen fixation, + denitrification

49
Q

how do plant roots take up nitrogen

A

via active transport + facilitated diffusion as ammonium (NH4+) and nitrate ions (NO3-)

50
Q

four types of bacteria involved in nitrogen cycle

A
  • nitrogen fixing bacteria
  • nitrifying bacteria
  • denitrifying bacteria
  • decomposera
51
Q

ammomification

A

production of ammonium compounds when decomposers feed on organic nitrogen-containing molecules

52
Q

nitrification

A

conversion of atmospheric nitrogen gas into ammonia by nitrogen- fixing bacteria in soil of root nodules of legumes

53
Q

examples of nitrifying bacteria

A

azotobacter - lives freely in soils
- rhizobium. lives inside root nodules of leguminous plants

54
Q

nitrogen fixation

A

conversion of ammonium ions by nitrifying bacteria, takes place in two stages:
- ammonium ions oxidised to nitrogen ions
- nitrite ions oxidised to nitrate ions

55
Q

two types of nitrifying bacteria + functions

A

nitrosomonas - oxidises ammonium compounds into nitrites
nitrobacter -oxidises nitrites into nitrates

56
Q

dentrificaion

A

conversion of nitrate ions to nitrogen gas by denitrifying bacteria

57
Q

denitrifying bacteria

A

anaerobic microorganisms, found in waterlogged soils, responsible for reduction of nitrate ions to nitrogen gas

58
Q

economic importance of nitrogen cycle

A

maximises plant growth + crop yield, increasing food production

59
Q

how can farmers increase nittprate content of soil

A
  • ploughing + drainage to aerate soil
  • application of fertilisers
  • growing legumes
60
Q

fertilisers

A

natural/artificial materials that are added to soils to provide essential nutrients + improve plant grwoth

61
Q

examples of natural fertilisers

A
  • manure
  • compost
  • treated sewage
62
Q

example of artificial fertiliser

A

ammonium nitarte

63
Q

eutrophication

A

process by which pollution by nitrogen containing fertilisers results in algal blooms + subsequent o2 level reduction in bodies of water

64
Q

how fertilisers can cause eutrophication

A
  1. fertiliser run-off into rivers + lakes
  2. nutrients build up in water
  3. algal bloom blocks sunlight
  4. aquatic plants can’t photosynthesise- less o2 produced
  5. die + decompose
  6. decomposers further deplete o2 levels
  7. animals can no longer respire aerobically so die
65
Q

how does digging drainage ditches affect habitats

A
  • habitat loss
  • reduction in biodiversity
  • may lead to eutrophication

biology (24 decks)

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