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Ecosystems Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Ecosystem

A

All the interactions between the living and non-living components in a defined area

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2
Q

Biome

A

Large ecosystem

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3
Q

Open ecosystem

A

When living things can move between ecosystems

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4
Q

Closed ecosystems

A

When living things cannot easily move between ecosystems e.g. islands

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5
Q

Niche

A

Role of a particular species

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6
Q

Biotic

A

Involves other living organisms

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7
Q

Biotic factors affecting ecosystems

A 
Predators
Food supply (prey)
Disease
Cooperation between species
Competition between species
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8
Q

Abiotic factors affecting ecosystems

A 
pH
Conc of pollutants
Temp (climatic)
Moisture/ rainfall/ relative humidity
O2 level
Soil type (edaphic)
Light intensities
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9
Q

How does low light intensity affect the ecosystem

A

Plants develop photosynthetic pigments that require less light
Grow larger leaves
Reproductive systems that only work in optimum light intensities

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10
Q

How does temp affect the ecosystem

A

Temp has the biggest effect on enzymes in the organisms that live in the ecosystem
May trigger migration/ hibernation
Dormancy/ leaf fall/ flowering in plants

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11
Q

How are ecosystems organised

A

In trophic levels

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12
Q

Producers in an ecosystem

A

Lowest trophic level

Involves autotrophs, chemotrophs and photoautotrophs

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13
Q

Autotrophs

A

Convert energy from environment into complex organic matter, then are used as respiratory substrates or for growth

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14
Q

Chemo/photoautotrophs

A

Use light/ chemicals to convert small inorganic molecules into complex organic ones

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15
Q

Consumers

A

Higher/est trophic levels
Feed on complex organic matter made by autotrophs and other organisms and use the products of digestion as respiratory substrates or for growth
1’<2’<3’

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16
Q

Decomposers

A

Feed on waste or dead organisms to gain energy by digesting and respiring organic matter
Recycling - returns inorganic ions to the air/soil

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17
Q

Why are ecosystems dynamic

A

Always changing due to many interlaced interactions that any small change causes several others–> alters flow of biomass

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18
Q

Types of changes in ecosystems

A

Cyclical - repeated change e.g. seasons, day/night
Directional - in one direction e.g. global warming, erosion
Unpredictable/ erratic - no rhythm or constant direction e.g. volcanic eruption

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19
Q

Components of an ecosystem

A

Habitat- where an organism lives

Population- where all the members of a species living in some place at a given time

Community- all the populations of diff species who live in some place at a given time, who can interact w/ each other

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20
Q

Why are there fewer consumers at higher levels

A

Energy (biomass) is lost at each trophic level so unavailable to organism at next trophic level, therefore there’s less energy available to sustain living tissue

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21
Q

How is biomass lost

A

Cellular respiration - conversion to inorganic molecules such as CO2 and H2O
Excretory materials
Indigestible matter
Not everything is fit for consumption e.g. bones
Transferred at metabolic heat (movement)

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22
Q

Loss of biomass in endotherms vs ectotherms

A

Ectotherms use less energy in maintaining body heat so there is more biomass available

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23
Q

Saprotrophs

A

Secrete extracellular enzymes onto dead/waste materials

Digest the materials into small molecules which are then absorbed and stored/respired

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24
Q

Why is the producer efficiency v. low

A

Approx 90% of light is reflected, unusable wavelength and transmitted through leaf
Limiting factors
Energy used for photosynthetic reactions

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25
Q

Succession

A

Progressive change in the structure and species composition in a community
Affects vegetation first but then brings about corresponding changes in bacteria, fungi, insects, birds and mammals

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26
Q

Climax community

A

Final, stable community that exists after the process of succession has occurred
Usually woodland communities

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27
Q

Deflected succession

A

Happens when succession is stopped/interfered w/ e.g. grazing so a plagioclimax develops as the species are stuck in that one stage of succession

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28
Q

Pioneer species

A

Species that begin the process of succession, often colonising an area as the first living thing there

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29
Q

Primary succession

A

If a community is developed from bare ground e.g. volcanic eruptions
Pioneer communities start succession —> conditions change (build up or organic material /nutrients) and other species succeed them
Larger plants continuously succeed small plants until a climax community is formed

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30
Q

Secondary succession

A

Does not start from bare ground

Takes place on a previously colonised but damaged/disturbed habitat

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31
Q

Why are sand dunes helpful in terms of succession

A

Shows us the stages of succession in order of occurrence whereas usually we only see the current stage

32
Q

How does succession affect species diversity

A

Increases it however dominant species may outcompete the smaller species killing whole species off

33
Q

What is weathering and how does it contribute to succession?

A

Breakdown or decomposition of rock in situ
Decomposition of rock increases soil depth/ changes soil composition
Favouring new species

34
Q

Calculating net primary production

A

Gross primary production = npp - products of respiration

35
Q

Calculating efficiency of energy transfer

A

Net production/ food intake x 100

36
Q

Plagioclimax

A

Sub-climax community when succession has been deflected

37
Q

Ways to deflect succession

A 
Mainly agriculture and human activity e.g. Grazing
Burning
Application of fertilisers
Application to herbicide
Exposure to excessive amounts of wind
38
Q

How does succession affect biomass

A

Increases it due to more organisms in the ecosystem

39
Q

Why should sub-climax communities be conserved

A

Higher species diversity than climax communities - still contain some sub-climax species and climax species
Results in conserving a much wider range of plants and animals that don’t live in the climax community

40
Q

Pioneer species on sand dunes

A

Species that can tolerate salty water, lack of fresh water and stable sand e.g. sea rocket

41
Q

Pioneer species on bare rock

A

Algae and lichens as they don’t need to be anchored into the soil

42
Q

Increasing primary productivity

A 
Some crops are planted early
Irrigating crops
Drought resistant crops
Using greenhouses
Crop rotation
Fertilisers (provides inorganic ions)
Pesticides/ pest resistant crops
43
Q

How does planting some crops early increase primary productivity?

A

Provides a longer growing season to harvest more light

44
Q

How does irrigating crops increase primary productivity?

A

Water is readily available for the light dependent stage of photosynthesis even when rainfall is below average

45
Q

How does growing crops in a greenhouse increases primary productivity

A

Provides a warmer temp —> increases the rate of photosynthesis

46
Q

How does crop rotation increase primary productivity

A

Stops reduction in soil levels of inorganic ions e.g. K^+ or NO3^-

47
Q

How does use of pesticides increase primary productivity?

A

Prevents loss of biomass and lowering yield of plant

48
Q

Why do plants need NH4+, NO3-, K+ & PO4 3-?

A

NH4+: Maintains pH
NO3-: Part of the nitrogen cycle
K+: Improves growth of leaves
PO4 3-: Improves growth of roots

49
Q

Increasing secondary productivity

A 
Harvesting animals before adulthood
Selective breeding
Animals treated w/ antibiotics
Zero grazing
Keeping environmental temp constant - prevents energy loss through homeostasis
50
Q

How does harvesting animals before adulthood increase secondary productivity

A

Minimises loss of energy as younger animals invest a larger proportion of energy into their growth

51
Q

How does selective breeding increase secondary productivity

A

Produces improved animal breeds w/ faster growth, increased egg production and increased milk production

52
Q

Zero grazing

A

Bringing food directly to animals

Maximises energy allocated to developing muscle by reducing need to move

53
Q

Processes in the carbon cycle

A 
Photosynthesis
Respiration (animals and plants)
Anaerobic respiration (dead organic matter and excreta)
Fossilisation
Combustion
Diffusion and carbonic acid formation
Diffusion
Decomposition
Feeding
Sedimentation
54
Q

Processes adding to atmospheric CO2

A

Respiration
Combustion
Diffusion frm the sea to the air

55
Q

Processes removing atmospheric CO2

A

Photosynthesis

Diffusion and carbonic acid formation in the ocean

56
Q

Sedimentation

A

CO2 is used by plankton to produce calcium carbonate shells. When these die, their shells sink to the ocean floor and are buried by sediment

57
Q

Fossilisation

A

Organic matter is buried and copressed over millions of years forming gas, coal and oil

58
Q

Human interferences that affect the carbon cycle

A

Combustion
Population size (respiration and waste)
Deforestation
Farming

59
Q

Effects of human interferences w/ the carbon cycle

A

Global warming/enhanced greenhouse effect
Ocean acidification from carbonic acid
Warmer sea - less CO2 absorbed
Removing photosynthesisers
Releasing more CO2 through combustion of trees

60
Q

Processes in the nitrogen cycle

A 
Nitrification
Assimilation
Denitrification
Nitrogen fixation by organic and non-living processes
Ammonification
61
Q

What is nitrogen fixing

A

Conversion of atmospheric nitrogen (N2) into nitrogen containing compounds
Carried out by denitrifying bacteria (Azobacter) and mutualistic bacteria (Rhizobium) in plant root nodules. Nitrogenase reduces N2 to NH3 to form amino acids
Atmospheric fixation
Haber process to make chemical fertilisers

62
Q

Atmospheric fixation

A

Converting nitrogen gas into nitrates by lightning. The energy from lightning breaks the N2 into atoms which combine w/ oxygen and dissolve in rain

63
Q

Ammonification

A

Converting nitrogen containing compounds (e.g. urea from urine) to NH3
Carried out by decomposers

64
Q

Nitrification

A

Conversion of ammonium ions to nitrites (by Nitrosomonas) and then into nitrates (by Nitrobacter) by nitrifying bacteria (chemoautotrophs)

65
Q

Assimilation

A

Nitrates in the soil are absorbed from the soil by plants and algae. Animals then eat plants and assimilate nitrogen compounds too

66
Q

Denitrification

A

Conversion of soil nitrates to atmospheric nitrogen. Carried out by denitrifying bacteria in anaerobic conditions (e.g. waterlogged soil) who use the nitrates as the final e- acceptor in respiration instead of O2

67
Q

Human activities affecting the nitrogen cycle

A

Use of fertiliser - nitrification, algae use up all the oxygen

68
Q

Processes removing atmospheric nitrogen

A

Nitrogen fixation by bacteria
Atmospheric fixation
Haber process

69
Q

Processes adding to atmospheric nitrogen

A

Denitrification

70
Q

Similarities in nitrogen and carbon cycles

A

Involves plants and animals
Involves anaerobic respiration (decomposers)
Both cycles involve atmospheric chemicals

71
Q

Differences in nitrogen and carbon cycles

A

Involves sea in cc
No fixation of CO2
Only uses organic processes in cc
N is fixed by bacteria vs on plants

72
Q

what are transects used for and what are their types?

A

Look for changes in vegetation across a habitat
Line- at reg. intervals, note of which species are touching the tape
Belt- at reg. intervals, place a quadrat next to the line (interrupted belt transect) or move the quadrat along the line (continuous), used to sample succession

73
Q

Estimating pop. size

A

Mean number of a species in a quadrat/ faction of the total habitat area covered by a single quadrat

74
Q

Deciding how many samples to take

A

In a pilot study take random samples looking at species distribution
Plot quadrat number against cumulative frequency
When curve levels off use that number of quadrats

75
Q

Units to measure primary productivity on land and on water

A

land: gm-2 yr-1
water: gm-3 yr-1

76
Q

Decomposes in the nitrogen cycle

A

Pass urea to next stage

Biology (13 decks)

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