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genetics, evolution and ecosystems > ecosystems > Flashcards

ecosystems Flashcards

organisms go brr but together

1
Q

what is an ecosystem?

A

a natural unit which consists of defined areas and all the communities within it interacting with eachother and the non living components of their environment

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2
Q

what is a community?

A

collection of different populations which occur together

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3
Q

what is a population?

A

group of individuals of the same species which occupy a particular habitat

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4
Q

what are the biotic factors that affect an ecosystem?

A
  • competition
  • prey
  • predator
  • mutualism (symbiosis)
  • mates
  • parasitism
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5
Q

what are the abiotic factors that affect an ecosystem?

A
  • light
  • temperature
  • water
  • oxygen
  • edaphic (soil) factors
  • pH
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6
Q

how does light affect an ecosystem?

A

required for the light dependent stage of photosynthesis

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7
Q

how does temperature affect an ecosystem?

A

optimum temperature required for enzyme based metabolic reactions

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8
Q

how does water availability affect an ecosystem?

A

required to maintain turgidity in plants and used in LDR

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9
Q

how does oxygen affect an ecosystem?

A

produced in photosynthesis and used in respiration to produce ATP

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10
Q

how do edaphic factors affect an ecosystem?

A

different particle sizes contain different water levels

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11
Q

why do abiotic factors affect plants more than animals?

A

animals can
- move to find shelter/water
- migrate to warmer or colder temperatures
- regulate their temperature so less affected by change
- survive from different food sources

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12
Q

what is photoautotrophic?

A

plants using sunlight as a source of energy

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13
Q

how is light a source of energy for almost all communities?

A
  • light energy absorbed by photoautotrophs is converted into chemicals via photosynthesis
  • used to make organic compounds from inorganic sources eg. glucose to CO2
  • heterotrophs ingest these compounds to be broken down by respiration and produce ATP
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14
Q

what are the 4 trophic levels?

A
  • producer
  • primary consumer
  • secondary consumer
  • tertiary consumer
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15
Q

how is energy lost between trophic levels?

A
  • used in respiration
  • lost as heat energy
  • energy in excretion
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16
Q

what is biomass?

A

mass of living organisms present in a particular place

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17
Q

biomass calculasiton

A

biomass present x number of organisms in trophic levels

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18
Q

what are the problems with biomass?

A
  • only relevant for a “snapshot” time and doesn’t account for seasonal change
  • biomass of primary consumer may exceed phytoplankton whose productivity can be low due to environmental conditions (results in a non-pyramid shape)
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19
Q

what are the problems with measuring dry biomass?

A
  • has to be killed, heated to 80 degrees and all water evaporated
  • to counteract this, small samples can be used but it isnt reflective
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20
Q

what are the problems with fresh mass?

A

includes water content which is variable within organisms which makes the data unreliable

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21
Q

what do pyramids of energy represent?

A

the flow of energy through each trophic level over a specified period of time and provide a measure of productivity

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22
Q

what is the unit of measurement of pyramids of energy?

A

kJ/m^2/yr which means it takes into account seasonal fluctuations

23
Q

why is the pyramid of energy never inverted?

A

energy is always lost on transfer

24
Q

what is the limitation of pyramids of energy?

A

they don’t show the fate of the energy loss

25
what is productivity?
the rate of generation of biomass in an ecosystem kg/m^2/day
26
what is primary production?
production of chemical energy in organic compounds by producers
27
what are the two types of primary production?
- Gross Primary Production: amount of chemical energy as biomass that a producer creates in a given time - Net Primary Production: amount of chemical energy not consumed by respiration (NPP=GPP-resp)
28
how can human activity manipulate the transfer of biomass?
- agriculture requires specific conditions for optimal growth and removes competition as well as the threat of predators - in animal farming there are only 3 trophic levels and crop farming theres only 2 so minimal energy lost
29
what is decomposition?
process in which a compound is broken down into smaller molecules
30
why is decay essential to ecosystems?
necessary to recycle nutrients such as carbon and nitrogen compounds
31
what type of organisms are involved in decay?
- detritivores eg. earthworms, beetles, slugs - decomposers eg. microscopic bacteria and fungi
32
how do detritivores feed?
ingest and digest organic matter (internal digestion) which increases the surface area for decomposers to act upon
33
how do decomposers feed?
saprophytic digestion (organic to inorganic nutrients) by secreting enzymes
34
what are azotobacter?
nitrogen fixing bacteria found in soil that converts nitrogen gas into ammonia which plants can use
35
what are rhizobium?
nitrogen fixing bacteria found in root nodules of legumes that convert nitrogen gas (N2) into ammonia (NH3)
36
what are nitrosomonas?
found in soil or fresh water, are useful in bioremediation and convert ammonium ions to nitrites(NO2-)
37
what are nitrobacter?
found in soil and converts nitrites to nitrates (NO3-)
38
what do denitrifying bacteria do?
convert nitrates into nitrogen gas
39
what is ammonification?
process by which decomposers convert nitrogen-containing molecules from dead organisms and turn it into ammonia
40
how is carbon stored?
- atmosphere as carbon dioxide - sedimentary rocks - fossil fuels - soil - dissolved in ocean
41
how do organisms take carbon out of the atmosphere?
- photosynthesis uses carbon in carbon fixation - terrestrial plants use CO2 from the air - aquatic organisms use dissolved in the ocean
42
what is succession?
change in an ecosystem from simple to complex over time
43
what is primary succession?
succession on newly formed/exposed land eg. volcanic eruptions cause dried magma to form new land, or exposed rock when sea levels drop
44
what is secondary succession?
- plants and animals recolonize a habitat after a major disturbance that significantly alters an area but does not render it completely lifeless - occurs faster than primary succession
45
what is a pioneer species?
first species to colonise new land
46
what are some examples of pioneer species?
- lichen - marram grass - algae
47
what are the adaptations of pioneer species?
- ability to produce many spores or seeds which are carried by wind - seeds that germinate rapidly rapidly - produce their own energy (photosynthesis) - tolerate extreme environments - ability fix nitrogen anywhere
48
what is the process of primary succession?
- seeds/spores reach new land and grow - they die and decompose to form a layer of basic soil - seeds of smaller plants eg grass grow on the new soil - as they die the soil deepens - larger plants can now grow as more water can stored in deeper soils - large trees can now survive - the final species to colonise the new land become the dominant species of the now complex ecosystem - final community is called the climax community
49
what is deflected succesion?
human activities often prevent or interrupt the process of succession
50
how do humans prevent a climax community from forming?
- mowing grass prevent trees and shrubs growing - livestock eat shoots so nothing new can grow
51
what are the methods of deliberate prevention of succession?
- managed burning to get rid of shrubs and trees - grazing animals
52
how are dead organisms utilised in the nitrogen cycle?
- decomposers break down nitrogen-containing compounds in waste material to form ammonia - when released into water in the soil, ammonia forms ammonium ions which can then be converted into nitrate
53
what is meant by the term nitrogen fixation?
the conversion of nitrogen from the atmosphere into ammonia
54

genetics, evolution and ecosystems (6 decks)

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