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biology year 2 > Population in Ecosystems > Flashcards

Population in Ecosystems Flashcards

1
Q
A
  • intraspecific competition
  • compete with fertile males to mate
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2
Q

describe how the mark-release-recapture method could be used to determine the population of A.aegypti at the start of the investigation?

A
  • capture, mark and release
  • leave time for mosquitoes to disperse before second sampling
  • population size = no. caught in 1st sample x no. caught in 2nd sample / number marked in second sample
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3
Q

the release of radiation-sterilised A.aegypti has not been very successful in controlling the transmission of dengue.

suggest why?

A

radiation affects attractiveness of A.aegypti

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4
Q

suggest why the scientists released more transgenic males every week?

A
  • maintain competition
  • as more transgenic males die
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5
Q

the release of transgenic males proved successful in reducing the number of A.aegypti.

describe how the results in the figure support this conclusion?

A

number lower after 12 weeks

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6
Q

define habitat?

A

place where an organism lives

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7
Q

define population?

A

all the organisms of one species in a habitat

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8
Q

define community?

A

populations of diff species in a habitat

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9
Q

define ecosystem?

A

a community, plus all the non-living condtions in the area in which it lives.

can be small/large

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10
Q

define abiotic conditions?

A

non-living features of the ecosystem

e.g. temp, availability of water

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11
Q

define biotic conditions?

A

living features of ecosystem

e.g. presence of food / predators

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12
Q

define niche?

A

role of a species within its habitat

e.g. what it eats, where and when it feeds

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13
Q

define adaptation?

A

a feature that members of a species have that increases their chance of survival and reproduction

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14
Q

the niche a species occupies within its habitat includes what?

A
  • biotic interactions - organism eats, what its eaten by
  • abiotic interactions - oxygen breathes in, CO2 breathes out
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15
Q

every species has its own unique…

A

niche

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16
Q

if 2 species try to occupy the same niche, what happens?

A
  • will compete
  • one species more successful than other
  • until one species left
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17
Q

define natural selection?

A

organisms with better adaptations more likely to survive, reproduce and pass on favourable allele

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18
Q

adaptations to abiotic conditions?

A
  • otters have webbed paws - can walk and swim - can live and hunt on land and water
  • seals have thick layer blubber - keeps them warm in coldest seas - can live in places where food plentiful
  • hedgehogs hibernate - lowers metabolism rate - conserve energy during cold months
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19
Q

adaptations to biotic conditions?

A
  • sea otters use rocks smash open shellfish and clam - gives access to another source of food
  • male frogs prod mating calls - attract mate of same species - successful mating more likely
  • bacteria prod antibiotics - kill other species of bacteria in same area - less competition
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20
Q

define population size?

A

total number of organisms of one species in habitat

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21
Q

define carrying capacity?

A

maximum stable population size of a species that an ecosystem can support

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22
Q

list some abiotic factors?

A
  • light
  • water
  • space
  • temp
  • chemical composition
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23
Q

what is interspecific competition?

A

when organisms of different species compete with each other for same resources

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24
Q

what can interspecific comp lead to ?

A
  • resources available to both species reduced
  • pop limited by lower amount of food
  • less energy for growth and reproduction
  • populations smaller
25
Q

if 2 species are competing but one is better adapted to its surroundings than other, what happens?

A

less well adapted OUTCOMPETED

26
Q

how does the grey squirrel have a better chance of survival?

A
  • larger
  • store more fat
  • eats wider range of food
27
Q

what is intraspecific competition?

A

when organisms of same species compete with each other for same resources

28
Q

what can intraspecific comp lead to?

A
  • pop inc when resources plentiful
  • more organisms competing for same amount of space and food
  • resources = limiting
  • pop declines
  • smaller pop = less comp
  • better for growth and reprod
29
Q

what is predation?

A

where organism kills and eats another organism

30
Q

the population sizes of predators and prey are interlinked.

how?

A

as population of one changes, causes other population to change

31
Q

describe the predator-prey relationship?

A
  • prey pop inc
  • more food for pred, pred pop inc
  • more prey eaten, prey pop dec
  • less food for pred
  • pop dec
32
Q

what are non-motile organisms?

A

organisms that dont move about e.g. plants

33
Q

what are quadrats?

A

square frame divided into a grid

34
Q

how are quadrats used?

A

placed on ground at random diff points in area

35
Q

define species frequency?

A

how often species found / number of individuals of each species reacorded in each quadrat

36
Q

how can percentage cover be found?

A

counting how much quadrat covered by species

37
Q

what is percentage cover a quick way of?

A

investigating pop

38
Q

to cover larger distances, what can you do?

A

quadrats places at intervals along line (interrupted belt transects)

39
Q

mark-release-recapture method?

A
  • capture sample of species
  • mark in harmless way
  • release back into habitat
  • wait week, take 2nd sample
  • count how many of 2nd sample marked

TOTAL POP SIZE = NUMBER CAUGHT IN 1ST SAMPLE X NUMBER CAUGHT IN 2ND SAMPLE / NUMBER MARKED IN 2ND SAMPLE

40
Q

what are the assumptions you have to make in the mark-release-recapture method?

A
  • sample had enough time and opportunity to mix back in with pop
  • marking not affected individuals’ chance of survival
  • no change in pop size due to births, deaths and migration
41
Q

investigating the effect of soil pH on marram grass in coastal ecosystem?

A
  • place tape measure in straight line from shore heading inland

  • take 1m^2 quadrat divided into 100 squares
  • starting from shore, place quadrat next to tape measure
  • count squares containing marram grass and record result in table as percentage cover
  • at each sample point, measure pH and record
  • repeat every 10m along line
42
Q

how can you measure pH?

A
  • use digital probe

OR

  • take sample
  • add barium sulfate, distilled water and pH indicator
  • shake
  • compare colour against pH chart
43
Q

why does pH inc near shore?

A
  • sand/soil contain shell fragments
  • made of calcium carbonate
  • alkaline
44
Q

why does pH dec as you move inland?

A

rotting veg adds organic matter to soil = acidic

45
Q

safety issues?

A
  • local tide times
  • suitable clothing and footwear
  • wash hands before eating
46
Q

ethical issues?

A
  • people trample on marram grass
  • erosion
47
Q

define succession?

A

process by which an ecosystem changes over time

48
Q

primary succession?

A
  • happens on newly formed / exposed land
  • no soil / organic material
49
Q

secondary succession?

A
  • happens on cleared land
  • e.g. deforested land
  • soil remains
50
Q

define pioneer species?

A

first species to colonise an area

51
Q

process of primary succession?

A
  • pioneer species colonise rocks e.g. lichens grow on & break down rocks –> rel minerals
  • lichens die, and decompose = thin soil
  • thickens as more organic material formed
  • other species e.g. moss can grow
  • larger plants need more water - move in as soil deepens
  • soil deepen as larger plants die and decompose
  • larger plants grow and out-compete smaller plants = dominant species
  • biodiversity inc
  • soil deep and rich enough in nutrients to support large trees
  • climax community formed
52
Q

process of secondary succession?

A
  • happens in same way as primary
  • already soil layer - starts later
  • pioneer species = larger plants e.g. shrubs
53
Q

what is the final stage of succession called?

A

climax community

54
Q

define climatic climax?

A

climax community for a particular climate

55
Q

define plagioclimax?

A

when succession stopped artificially

56
Q

what are the ways to manage succession to conserve the moorland ecosystem?

A
  • animals allowed graze on land
  • similar to mowing - animals eat growing points of shrubs and trees –> stops establishing themselves
  • keeps veg low
  • managed fires lit
  • secondary succession occurs after fire
  • pioneer species conserved
57
Q

define conservation?

A

protection and management of species and habitats in a sustainable way

58
Q

define sustainable?

A

enough resources are taken to meet needs of people today, without reducing ability of people in future to meet their own needs

biology year 2 (29 decks)

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