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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
source of energy for ecosystems
light energy (other than ecosystems that rely on chemosynthesis)
26
trophic level
position organism holds in a food chain, food web, pyramid of numbers or pyramid. of biomass
27
biomass, how is it transferred, how is it measured
- 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
formula for efficiency of biomass transfer
efficiency = biomass transferred ————————— x 100 biomass intake
29
why is some energy never taken in at each trophic level
- some parts of food not consumed - some parts of food indigestible - plants can’t use all light energy as some is wrong wavelength
30
why is some energy lost at each trophic level
respiration, lost as heat
31
pyramid of biomass
table of the dry mass of living material at each trophic level of a food chain forms shape of a pyramid
32
net + gross primary productivity
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
how is npp calculated
subtracting chemical energy generated in respiration (R) from gpp npp = gpp - R
34
primary succession
area previously devoid of live colonised by pioneer species
35
pioneer species
species that can survive + colonies bare rock or sand, e.g: lichens
36
process of primary succession
- pioneer species colonies area - die, decompose, and add nutrients to ground - over time, allows more complex organisms to survive
37
seres
various intermediate stages in succession progressing towards a climax community
38
secondary succession
type of succession in which a habitat is re-colonised after a disturbance
39
climax community, how is it reached
- 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
how does succession affect species diversity + stability of a community
succession increases species diversity + stability of the community
41
examples of organisms that play an important role in decay
detrivores - feed on dead organic matter saprotrophs - feed by extracellular digestion
42
extracellular digestion by saprotrophs
release enzymes which catalyse the breakdown of dead plant + animal material into simpler organic matter
43
carbon cycle
cycle through which carbon (in form of CO2) moves between living organisms + the environment, involving respiration, photosynthesis + combustion
44
stages of carbon cycle
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
global warming
gradual rise in average temp of earth due to increasing atmospheric levels of co2 + methane gas
46
greenhouse effect
increase of global temps caused by trapping of solar heat by gases in atmosphere
47
how might global warming affect the natural world
- 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
nitrogen cycle
cycles through which nitrogen moves between living organisms + the environment, involving ammonification, nitrification, nitrogen fixation, + denitrification
49
how do plant roots take up nitrogen
via active transport + facilitated diffusion as ammonium (NH4+) and nitrate ions (NO3-)
50
four types of bacteria involved in nitrogen cycle
- nitrogen fixing bacteria - nitrifying bacteria - denitrifying bacteria - decomposera
51
ammomification
production of ammonium compounds when decomposers feed on organic nitrogen-containing molecules
52
nitrification
conversion of atmospheric nitrogen gas into ammonia by nitrogen- fixing bacteria in soil of root nodules of legumes
53
examples of nitrifying bacteria
azotobacter - lives freely in soils - rhizobium. lives inside root nodules of leguminous plants
54
nitrogen fixation
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
two types of nitrifying bacteria + functions
nitrosomonas - oxidises ammonium compounds into nitrites nitrobacter -oxidises nitrites into nitrates
56
dentrificaion
conversion of nitrate ions to nitrogen gas by denitrifying bacteria
57
denitrifying bacteria
anaerobic microorganisms, found in waterlogged soils, responsible for reduction of nitrate ions to nitrogen gas
58
economic importance of nitrogen cycle
maximises plant growth + crop yield, increasing food production
59
how can farmers increase nittprate content of soil
- ploughing + drainage to aerate soil - application of fertilisers - growing legumes
60
fertilisers
natural/artificial materials that are added to soils to provide essential nutrients + improve plant grwoth
61
examples of natural fertilisers
- manure - compost - treated sewage
62
example of artificial fertiliser
ammonium nitarte
63
eutrophication
process by which pollution by nitrogen containing fertilisers results in algal blooms + subsequent o2 level reduction in bodies of water
64
how fertilisers can cause eutrophication
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
how does digging drainage ditches affect habitats
- habitat loss - reduction in biodiversity - may lead to eutrophication

biology (24 decks)

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