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Biology > Populations in ecosystems > Flashcards

Populations in ecosystems Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

define ecosystem

A

community of species and the abiotic factors in that habitat and can range in size

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2
Q

define carrying capacity

A

the maximum pop. size a climax community/ecosytem can support and sustain

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3
Q

what are the 3 key things of ecosystems?

A
  1. dynamic
  2. have energy flow
  3. recycles elements
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4
Q

what 2 things can affect carrying capacity?

A
  1. effect of abiotic factors

2. biotic factors (interactions between organisms)

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5
Q

name the 5 abiotic factors which can effect carrying capacity?

A

temp, light, pH, H2O availability, humidity

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6
Q

how can temp affect carrying capacity?

A

increase: enzymes denature
decrease: reduce metabolic rate
= reduce carrying capacity

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7
Q

how can light affect carrying capacity?

A

increase = increase photo.

= carrying capacity of plants + those who consume them increases

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8
Q

how does pH affect carrying capacity?

A

pop. of species increase where there’s the optimum pH

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9
Q

how does a limited H2O availability affect carrying capacity?

A

pop. scarce

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10
Q

how does humidity affect carrying capacity?

A

affects transpiration rates (increase, decrease transpiration)
= depends on the adaptations to humidity

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11
Q

define interspecific competition?

A

competition between different species

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12
Q

define intraspecific competition?

A

competition between same species

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13
Q

how does predation affect carrying capacity?

A

decrease prey = increase comp between predators = decrease food availability

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14
Q

define community

A

populations of different species occupying the same area/habitat

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15
Q

define population

A

all organisms of the same species which occupy the same area/habitat

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16
Q

define habitat

A

where an organism lives

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17
Q

define microhabitat

A

smaller unit of an ordinary habitat

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18
Q

define ecological niche

A

where an organism lives and its role in the niche

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19
Q

increase repeats increases the _______ of the ____ which means its representative of the population so can make _____ conclusions.

A

reliability, mean, valid

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20
Q

when are quadrats used?

A

for slow moving or non-motile organisms

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21
Q

what does a point quadrat work out?

A

frequency

22
Q

what does a frame quadrat work out?

A

% cover (each square represents a %)

23
Q

name the 3 things you have to consider when using quadrats

A
  1. size of quadrat
  2. no. of samples
  3. position of quadrat
24
Q

describe random sampling in 6 steps

A
  1. 2 tape measures at right angles
  2. random no. generator
  3. place at the coordinate
  4. cound/collect
  5. record data
  6. calculate mean after repeating at least 20 times
25
Q

how many repeats should i do? (4)

A
  1. large no. = reliable
  2. carry out a stats test
  3. calculate a running mean
  4. need to be done in time available
26
Q

when should systematic sampling be used?

A

environmental gradient or change to the abundance/distribution of organisms

27
Q

name the 2 types of systematic sampling

A
  1. line

2. belt

28
Q

describe belt transect method in 3 steps

A
  1. lay out tape + place frame quadrat at right angle
  2. predetermined, equal intervals move quadrat
  3. record % cover
29
Q

what is the advantage of using a transect

A

measures abundance (% cover of frequency)

30
Q

name the 2 disadvantages of using a transect

A
  1. can take a long time for large sample

2. species overlooked if interval too large

31
Q

define abundance

A

no. of individual species in an area

32
Q

name the 2 ways abundance is measured

A

% cover and frequency

33
Q

what is % cover?

A

estimate of an area that a species covers

34
Q

what are the advantages and disadvantage of % cover?

A

+: useful if species abundant, difficult to count + data collected quickly
-: overlapping of plants

35
Q

what is frequency? + formula

A

likelihood of species in quadrat

no. of quadrats containing species / total no. of quadrats x 100

36
Q

name the advantages and disadvantages of calculating frequency

A

+: quick idea of the species present/distribution

-: not as much data + not as reliable

37
Q

when is MRR used?

A

for estimating the pop. size of motile organisms

38
Q

describe the method of MRR in 5 steps

A
  1. capture organism
  2. mark (avoid harming them + increase predation)
  3. release + allow enough time to reintegrate
  4. collect 2nd sample, count/record how many marked/unmarked
  5. use formula (lincoln Index)
39
Q

what is the formula for MRR (lincoln)?

A

no. of organism in sample 1 x no. of organisms in sample 2 / no. of recaught organisms

40
Q

name the 5 assumptions of MRR?

A
  1. sufficient time to reintegrate
  2. no immigration/migration
  3. few/no deaths/births
  4. mark/label doesn’t rub off
  5. marking doesn’t increase predation
41
Q

define succession

A

change in community over time due to change in abiotic factors and/or species present

42
Q

define pioneer species + 2 examples

A

1st species to colonise an area i.e. lichen, algae

43
Q

name the 5 features of pioneer species

A
  1. wind dispersed seeds
  2. rapid germination (no dormancy period)
  3. ability to photo.
  4. can fix nitrogen
  5. tolerant to extreme conditions
44
Q

define climax community

A

table community of species, no further succession

45
Q

4 features of climax community

A
  1. increased biomass
  2. complex food webs
  3. increase variety of food/habitats
  4. abiotic conditions less hostile
46
Q

define primary succession

A

no soil, bare rock

47
Q

define secondary succession

A

succession faster as soil already present + seeds still present

48
Q

define plagioclimax

A
  • human interference to prevent succession
  • done to conserve a habitat that would be outcompeted
    i. e. grazing, coppicing, pollarding
49
Q

describe primary succession in 7 steps

A
  1. pioneer species
  2. weathering of rock = soil
  3. pioneer species decompose (OM added)
  4. mosses/ferns colonise = less hostile
  5. organisms die/decompose + continued weathering
  6. small flowering plants, grasses, shrubs, trees
  7. climax community = equilibrium
50
Q

define conservation

A
  • management of the earth’s natural resources so that max. use can be made in future
  • intervention by humans to maintain biodiversity
51
Q

name the 3 reasons why we conserve habitats?

A
  • ethical (respect for organisms)
  • economic (potential to make different substances/medicines/biomimetics)
  • cultural (entertain us, adds interests, fulfill us)

Biology (25 decks)

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