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genetics, evolution and ecosystems > ecosystems > Flashcards

ecosystems Flashcards

organisms go brr but together

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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
Q

what is productivity?

A

the rate of generation of biomass in an ecosystem kg/m^2/day

26
Q

what is primary production?

A

production of chemical energy in organic compounds by producers

27
Q

what are the two types of primary production?

A
  • 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
Q

how can human activity manipulate the transfer of biomass?

A
  • 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
Q

what is decomposition?

A

process in which a compound is broken down into smaller molecules

30
Q

why is decay essential to ecosystems?

A

necessary to recycle nutrients such as carbon and nitrogen compounds

31
Q

what type of organisms are involved in decay?

A
  • detritivores eg. earthworms, beetles, slugs
  • decomposers eg. microscopic bacteria and fungi
32
Q

how do detritivores feed?

A

ingest and digest organic matter (internal digestion) which increases the surface area for decomposers to act upon

33
Q

how do decomposers feed?

A

saprophytic digestion (organic to inorganic nutrients) by secreting enzymes

34
Q

what are azotobacter?

A

nitrogen fixing bacteria found in soil that converts nitrogen gas into ammonia which plants can use

35
Q

what are rhizobium?

A

nitrogen fixing bacteria found in root nodules of legumes that convert nitrogen gas (N2) into ammonia (NH3)

36
Q

what are nitrosomonas?

A

found in soil or fresh water, are useful in bioremediation and convert ammonium ions to nitrites(NO2-)

37
Q

what are nitrobacter?

A

found in soil and converts nitrites to nitrates (NO3-)

38
Q

what do denitrifying bacteria do?

A

convert nitrates into nitrogen gas

39
Q

what is ammonification?

A

process by which decomposers convert nitrogen-containing molecules from dead organisms and turn it into ammonia

40
Q

how is carbon stored?

A
  • atmosphere as carbon dioxide
  • sedimentary rocks
  • fossil fuels
  • soil
  • dissolved in ocean
41
Q

how do organisms take carbon out of the atmosphere?

A
  • photosynthesis uses carbon in carbon fixation
  • terrestrial plants use CO2 from the air
  • aquatic organisms use dissolved in the ocean
42
Q

what is succession?

A

change in an ecosystem from simple to complex over time

43
Q

what is primary succession?

A

succession on newly formed/exposed land eg. volcanic eruptions cause dried magma to form new land, or exposed rock when sea levels drop

44
Q

what is secondary succession?

A
  • 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
Q

what is a pioneer species?

A

first species to colonise new land

46
Q

what are some examples of pioneer species?

A
  • lichen
  • marram grass
  • algae
47
Q

what are the adaptations of pioneer species?

A
  • 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
Q

what is the process of primary succession?

A
  • 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
Q

what is deflected succesion?

A

human activities often prevent or interrupt the process of succession

50
Q

how do humans prevent a climax community from forming?

A
  • mowing grass prevent trees and shrubs growing
  • livestock eat shoots so nothing new can grow
51
Q

what are the methods of deliberate prevention of succession?

A
  • managed burning to get rid of shrubs and trees
  • grazing animals
52
Q

how are dead organisms utilised in the nitrogen cycle?

A
  • 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
Q

what is meant by the term nitrogen fixation?

A

the conversion of nitrogen from the atmosphere into ammonia

54
Q
A

genetics, evolution and ecosystems (6 decks)

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