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ecosystems Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

define ecosystem

A

all the interacting living organisms and the non-living conditions in an area

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2
Q

define community

A

all the populations of living organisms in a particular habitat

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3
Q

define habitat

A

the natural home or environment of an animal, plant or other organism

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4
Q

define population

A

a group of organisms of the same species that live in the same place at the same time

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5
Q

define species

A

the smallest and most specific taxonomic group. can breed to produce fertile offspring

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6
Q

define ecology

A

the study of relations of organisms to each other and their physical surroundings

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7
Q

what is meant by “ecosystems are dynamic”

A

dynamic ecosystems are constantly changing

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8
Q

define biotic factor

A

the living components of an ecosystem

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9
Q

define abitotic factor

A

non-living conditions of a habitat
e.g rainfall, temperature, light intensity

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10
Q

define edaphic factor

A

factors to do with soil

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11
Q

define food web

A

many interconnected possible routes of energy and biomass through an ecosystem

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12
Q

define food chain

A

a single possible route of energy and biomass through a food web

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13
Q

define trophic level

A

each stage in a food chain

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14
Q

what do the arrows represent in a food web

A

direction of energy flow

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15
Q

define heterotroph

A

another name for a consumer

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16
Q

define consumer

A

organisms that obtain their organic molecules and energy by feeding on other organisms

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17
Q

define primary consumer

A

animals that eat producers in a food chain

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18
Q

define secondary consumer

A

animals that eat primary consumers in a food chain

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19
Q

define tertiary consumer

A

animals that eat secondary in a food chain

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20
Q

define herbivore

A

animals that eat plants - primary consumers

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21
Q

define carnivore

A

animals that eat other animals - secondary consumer or higher

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22
Q

define omnivore

A

animals that eat both plants and other animals

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23
Q

define detritivore

A

animals that feed on detritus (dead and decaying material)

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24
Q

define decomposer

A

an organism that feeds on dead organic matter, turning the organic molecules into inorganic ions

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25
Q

role of detritivores in food webs

A

speed up decay by breaking down dead material into smaller pieces, increasing the surface area of decomposers to work on

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26
Q

role of decomposers in food webs

A

decomposers break down dead organisms releasing nutrients back into the ecosystem

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27
Q

define biomass

A

the mass of living material present in a particular place or in particular organisms

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28
Q

define dry mass

A

the mass of living material remaining once all the water has been removed

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29
Q

why is dry mass is a better indicvator of biomass than fresh mass

A

dry mass is a more reliable measure of mass as it exculdes fluctuating water concentrations

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30
Q

how to calculate the dry mass of each trophic levels in a food chain

A

organisms killed and placed in an oven until water has all evaporated - 2 identical mass readings

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31
Q

how to measure the energy content of organic matter

A

using calorimeter - burn matter and measure temperature rise of water

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32
Q

suitable units in a terrestrial ecosystem

A

gm^-2 grams per metre squared

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33
Q

suitable units in an aquatic ecosystem

A

gm^-3 grams per metre cubed

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34
Q

how does a pyramid of numbers represent data about an ecosystem

A

show number of each organism in a food chain - not always pyramid shaped
easy to count, hard to draw due to variation

35
Q

how does a pyramid of biomass represent data about an ecosystem

A

shows mass at each trophic level in a food chain - almost alwats pyramid shaped
easier to draw, might be skewed due to time of year or reproduction rate

36
Q

how does a pyramid of energy represent data about an ecosystem

A

shows energy available from each level - always pyramid
hard to calculate

37
Q

suitable units for the energy at each trophic level in a food chain

A

kJm^-2yr^-1 Kilojoules per metre squared per year

38
Q

how is energy transferred from one trophic level to the next

A

transferred between trophic levels as organisms feed on eachoteher.
only a small proportion of the food is converted into a new tissue and therefore only a small proportion of the energy is available for next level to eat

39
Q

define ecological effiency

A

the efficiency with which energy or biomass is transferred from one trophic level to the next

energy or biomass available after the transfer / energy or biomass available before the transfer x 100

40
Q

why is 1-3% of sunlight is converted into chemical energy in producers

A

not all energy used for photosynthesis - 90% reflected, some transmitted, some is unusable wavelength

other limiting factors eg water availability

proprtion of energy lost as it is used for photosynthetic reactions

41
Q

define gross production

A

total solar energy that plants convert to organic matter

42
Q

define net production

A

the energy converted into biomass and therefore available to the next trophic level

43
Q

define respiratory losses

A

energy used in respiration so not available to next trophic level

44
Q

define primary production

A

generation of biomass in a producer

45
Q

define secondary production

A

generation of biomass in a consumer

46
Q

why consumers convert only a small amount of the biomass

A

not all biomass eaten
energy transferred to environment - movement and respiration
some parts eaten but indigestible - lost as faeces
some energy lost from animal in excretory matierals

47
Q

why does biomass decreases at each trophic level in a food chain

A

each level receives less energy than the level before due to energy losses such as in respiration

48
Q

why are food chains with more than 4 trophic levels rare

A

not enough energy available as biomass to sustain another tier of organisms

49
Q

how have humans manipulated energy transder in farming to our advantafe

A

provide abiotic conditions needed ot thrive
remove competition from other species
remove threat of predators
minimise trophic levels so least amount of energy is lost

50
Q

importance of decomposers

A

decomposers break down the organic matter into small inorganic molecules that can then be used by producers

51
Q

importance of detritivores

A

speed up decay process by breaking down organic material into smaller pieces

52
Q

define nitrogen fixation

A

conversion of nitrogen gas to ammonium compounds

53
Q

define nitrification

A

conversion of ammonium compounds into nitrites and nitrates

54
Q

define denitrification

A

conversion of nitrates into nitrogen gas

55
Q

define ammonification

A

conversion of nitrogen compounds in dead organic matter or waste into ammonium compounds by decomposers

56
Q

microorganisms involved in the nitrogen cycle

A

nitrogen fixing: rhizobium
nitrifying: nitrosomonas (ammonia to nitrites)
nitrobacter (nitrires to nitrates)

dentrification: pseudomonas dentrificians (nitrates to nitrogen)

57
Q

why does co2 levels vary throughout time

A

rate of photosynthesis, so rate of use of co2 fluctuates with light intensity.
at night - co2 levels are higher as respiration continues but photosynthesis doesn’t.
co2 levels lower in summer - more light = more photosynthesis

58
Q

why have co2 levels increased over last 200 years

A

industry - increased burning of fossil fuels
deforestation - fewer large areas of trees - less photosynthesis removed

59
Q

how do scientists gather data about co2 levels thousands of years ago

A

looking at ice at poles that formed 1000s of years ago but has never melted. - air bubbles trapped in ice

60
Q

define succession

A

progressive replacement of one dominant type of species or community, until climax community is established

61
Q

define primary succession

A

occurs on land that has been newly formed, no soil or organic material to begin with.

62
Q

define secondary succession

A

occurs on land where soil is present but contains no plant or animal species

63
Q

define deflected succession

A

when the direction of succession is affected by farming or other human activities

64
Q

define pioneer species

A

the first organisms to colonise an area

65
Q

define sere

A

the steps in succession

66
Q

define climax community

A

final stage in succession, where community is in a stable state

67
Q

define plagioclimax

A

stage in succession where artificial or natural factors prevent natrual climax community from forming

68
Q

adaptations species have for being pioneer species

A

produce large number of seeds/spores to spread
seeds that germinate rapidly
able to photosynthesise
tolerance to extreme environments
ability to fix nitrogen from atmosphere - adds to mineral content of soil

69
Q

describe effect of pioneer species on envrionment

A

if they die, their organic matter makes the environment more able to support other species.

70
Q

describe how conditions of soil change as succession occurs.

A

weathering of bare rock produces particles that form the basis of soil.
pioneer species die and decompose = release organic product into soil

71
Q

why does succession occur

A

result of changes to the environment, causing plant and animal species to change

72
Q

define dominant species

A

most abundant species in an ecosystem

73
Q

describe change in niche number and number of species as succession progresses

A

niche number and biodiversity increases as succession continues.
niche - role organism plays.
as succession continues, more organisms available to eat/be eated
biodiversity can dip as climax community forms if dominant species outcompetes others

74
Q

why secondary succession is likey to occur more quickly than primary succession

A

soil is already present so time not spent eroding rock to form it

75
Q

why deflected succession might occure

A

grazing and trampling of vegetation
removing existing vegetation to plant other crops
burning to clear forests - often leads to increase of biodiversity - nutrtient-rich ash

76
Q

define lithosphere

A

plant succession that begins life on newly exposed rock surface

77
Q

define psammosere

A

succession that began life on newly exposed coastal sand

78
Q

define halosere

A

succession in a saline environment

79
Q

define hydrosere

A

succession which occures in an area of fresh water

80
Q

how can the abundance of plants be estimated

A

sampling with quadrats then multiplying up to size of whole area

81
Q

what is capture-mark-recapture and how to estimate pop. size with it

A

capture as many as possible and mark them
reslease and recapture as many as possible
proportion marked will be the same as for the entire population

82
Q

lincoln index to estimate the population size of a species

A

pop size = number marked x numver recaptured / number recaptured marked

83
Q

what are the assumptions made when using capture-mark-release-recapture

A

population is closed - no immigration or emmigration
no deaths between samples
marked organisms must mix completely with the rest of the population between sampling.

biology (8 decks)

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