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A - Biology > Topic 7C - Populations in Ecosystems DVY * > Flashcards

Topic 7C - Populations in Ecosystems DVY * Flashcards

ecosystems variation in population size investigating populations succession conservation

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1
Q

What is a habitat?

A

the place where an organism lives

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2
Q

what is a population?

A

all the organisms of one species in a habitat

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3
Q

what is a community?

A

populations of different species in a habitat make up a community

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4
Q

what is an ecosystem?

A

a community, plus all the non-living (abiotic) conditions in the area in which it lives

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5
Q

what are abiotic conditions?

A

the non-living features of the ecosystem

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6
Q

what are biotic conditions?

A

the living features of the ecosystems

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7
Q

what is a niche?

A

the role of a species within its habitat, a niche can only be occupied by one species

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8
Q

what is an adaption?

A

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

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9
Q

what does the niche a species occupies within its habitat include?

A

its biotic interactions - e.g. the organisms it eats, and those it’s eaten by
its abiotic interactions - e.g. the oxygen an organisms breathes in, and the carbon dioxide it breathes out

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10
Q

what happens when 2 species try to occupy the same niche?

A

they will compete with each other. one species will be more successful than the other, until only 1 of the species is left

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11
Q

what is the common pipistrelle bat’s niche?

A

this bat lives throughout Britain on farmland, open woodland, hedgerows and urban areas. it feeds by flying and catching insects using echolocation at a frequency of around 45 kHz

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12
Q

what is the soprano pipistrelle bat’s niche?

A

this bat lives in Britain in woodland areas, close to lakes or rivers. it feeds by flying and catching insects using echolocation, at a frequency of 55 kHz

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13
Q

what are the different adaptations?

A

physiological - processes inside their body
behavioural - the way an organism acts
anatomical - structural features of their body

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14
Q

how must organisms be adapted to their ecosystems?

A

every species is adapted to use an ecosystem in a way no other species can (niche)
organisms are adapted to both the abiotic and biotic conditions in their ecosystem

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15
Q

what are some examples of adaptation to abiotic conditions?

A

otters have webbed paws
seals have a thick layer of blubber
hedgehogs hibernate

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16
Q

how are otter’s webbed paws adaptions to abiotic conditions?

A

this means they can both walk on land and swim effectively. this increases their chance of survival because they can live and hunt both on land and in water

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17
Q

how are seal’s thick layers of blubber adaptions to abiotic conditions?

A

this helps to keep them warm in the coldest seas. this increases their chance of survival because they can live in places where food is plentiful

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18
Q

how is a hedgehog hibernating an adaption to abiotic conditions?

A

they lower their rate of metabolism over winter. this increases their chance of survival because they can conserve energy during the coldest months

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19
Q

what are some examples of adaptation to biotic conditions?

A

sea otters use rocks to smash open shellfish and clams
male frogs produce mating calls to attract females
some bacteria produce antibiotics

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20
Q

how is sea otter’s use of rocks to smash open clams an adaption to biotic conditions?

A

this increases their chance of survival because it gives them access to another source of food

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21
Q

how are male frog’s mating calls adaptions to biotic conditions?

A

this makes sure they attract a mate of the same species. this increases their chance of reproduction by making successful mating more likely

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22
Q

how is bacteria making antibiotics an adaption to biotic conditions?

A

these kill other species of bacteria in the same area. this increases their chance of survival because there’s less competition for resources

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23
Q

what is population size?

A

the total number of organisms of 1 species in a habitat

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24
Q

what is the carrying capacity?

A

the maximum stable population size of a species that an ecosystem can support. it varies as a result of both abiotic and biotic factors

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25
Q

what are examples of abiotic factors?

A

amount of light, water or space available
temperature of surroundings
chemical composition of surroundings

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26
Q

what happens when abiotic conditions are ideal?

A

organisms can grow fast and reproduce successfully

e.g. ideal temperature means less energy is used maintaining body temperature

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27
Q

what is interspecific competition?

A

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

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28
Q

what can happen as a result of interspecific competition?

A

the resources available to both populations are reduced. this means both populations will be limited by a lower amount of this resource. they’ll have less energy for growth and reproduction, so both population sizes lower

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29
Q

what happens if one species is better adapted than another?

A

the less well adapted species is likely to be out-competed - it won’t be able to exist alongside the better adapted species

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30
Q

what is intraspecific competition?

A

when organisms of the same species compete with each other for the same resource

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31
Q

what cycle happens as a result of intraspecific competition?

A

the population increases when resources are plentiful, so more organisms are competing for same resources
resources become limiting, population begins to decline
smaller population = less competition for resources, which is better for growth and reproduction, population grows again

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32
Q

what is predation?

A

where an organism kills and eats another organism. the population sizes of predators and prey are interlinked

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33
Q

what biotic factors cause population size to vary?

A

interspecific competition
intraspecific competition
predation

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34
Q

how are the population sizes of predators and prey are interlinked?

A

prey population increases, there’s more food for predators, so the predator population grows
more prey is eaten so prey population falls
less food for predators, so population decreases
etc.

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35
Q

how do you take samples?

A

choose an area to sample
samples should be random to avoid bias
use appropriate technique to take samples
repeat the process
parameters can then be estimated from the data collected

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36
Q

why must you repeat a sampling process?

A

taking as many samples as possible, this will reduce the likelihood that your results are down to chance

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37
Q

what are non-mobile organisms?

A

ones that don’t move about - like plants.

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38
Q

what should be used to investigate non-mobile organisms?

A

quadrats and transects can be used, slow-moving organisms can also be investigated in this way

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39
Q

what is a quadrat?

A

a square frame, usually divided into a grid of 100 smaller squares by strings across the frame

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40
Q

how are quadrats used?

A

they are placed on the ground at different points within the area you’re investigating. the species frequency, percentage cover or the number of individuals of each species is recorded in each quadrat

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41
Q

how can you measure percentage cover of a species?

A

by counting how much of the quadrat is covered by the species - you can count a square if it’s more than half-covered. percentage cover is a quick way to investigate populations and you don’t have to count all the individuals organisms

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42
Q

what can you use transects for?

A

to find out how plants are distributed across an area

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43
Q

what are belt transects?

A

quadrats are placed next to each other along the transect to work out species frequency and percentage cover along the transect.

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44
Q

what is an interrupted belt transect?

A

to cover a larger distance, quadrats can be placed at intervals along the line

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45
Q

how is mark-release-recapture carried out?

A

capture a sample of a species using an appropriate technique, and count them
mark them in a harmless way
release them back into their habitat
wait a week, then take a 2nd sample from the same population
count how many of the 2nd sample are marked

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46
Q

what is the equation used to estimate population size using mark-release-recapture?

A 
# caught in 1st sample x # caught in 2nd sample
-------------------------------------
# marked in 2nd sample
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47
Q

what assumptions are made in the mark-release-recapture investigation?

A

the marked sample has had enough time and opportunity to mix back in with the population
the marking hasn’t affected the individuals’ chance of survival, and the marking itself is still visible
there are no changes in population size due to births, deaths and migration during the period of the study

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48
Q

how to investigate the effect of soil pH on marram grass in a coastal ecosystem?

A

place a tape measure in a straight line from the shore, heading inland
take 1m^2 quadrat divided into 100 squares
place quadrat next to tape measure
count the squares containing marram grass and record the results as percentage cover
at each sample point, you should measure pH and record results in the table
repeat observations every 10m along the transect

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49
Q

how do you measure pH?

A

use a digital pH probe to take pH readings of sand or soil in the field.
or take a sample for testing - sieve it to remove debris, add barium sulfate, distilled water and pH indicator. shake thoroughly and then leave to settle. check colour against a pH chart

50
Q

what do the results of investigation into the effect of soil pH on marram grass in a coastal ecosystem show?

A

pH decreases as you move inland
as pH decreases from 8.5 to 7.5, percentage cover increases
after pH 7.5 percentage cover decreases

51
Q

why does pH decrease as you move inland?

A

soil contains lots of shell fragments near the shore, which are made of calcium carbonate - an alkaline compound.
inland, rooting vegetation adds organic matter to the soil, which is more acidic

52
Q

what does the change in percentage cover change?

A

you can’t say pH caused the trends in marram grass cover - there could be other factors affecting it, like soil moisture content, salinity, and competition

53
Q

what safety precautions are there in the investigation into the effect of soil pH on marram grass in a coastal ecosystem?

A

use tide timetables, so you know local tide times - low tide is best
wear suitable clothing and footwear for weather and terrain
wash your hands before eating after handling soil

54
Q

what ethical issues are there in the investigation into the effect of soil pH on marram grass in a coastal ecosystem?

A

all fieldwork affects the environment where it’s carried out

e.g. lots of people walking around cause soil erosion and marram grass can be killed by trampling.

55
Q

how can ethical issues be avoided in the investigation into the effect of soil pH on marram grass in a coastal ecosystem?

A

investigations should be planned to have the smallest impact possible
e.g. restrict where people walk to area being studied and try to avoid treading on the plants themselves

56
Q

what is succession?

A

the process by which an ecosystem changes over time. the biotic conditions change as the abiotic condition change

57
Q

what are the 2 types of succession?

A

primary succession

secondary succession

58
Q

where does primary succession happen?

A

this happens on land that’s been newly formed or exposed, there’s no soil or organic material to start with e.g. just bare rock

59
Q

where is an example of where primary succession can happen?

A

where a volcano has erupted to form a new rock surface, or where sea level has dropped exposing a new area of land.
bare rock

60
Q

where does secondary succession happen?

A

this happens on land that’s been cleared of all the plants, but where the soil remains

61
Q

where is an example of where secondary succession can happen?

A

after a forest fire or where a forest has been cut down by humans

62
Q

when does primary succession start?

A

when species colonise a new land surface. seeds and spores are blown in by the wind and begin to grow.

63
Q

what is a pioneer species?

A

the first species to colonise the area

64
Q

what are the abiotic factors like in primary succession?

A

they are hostile. only pioneer species grow because they’re specially adapted to cope with the harsh conditions

65
Q

what do the pioneer species do in primary succession?

A

they change the abiotic conditions - they die and microorganisms decompose the dead organic material (humus) this forms a basic soil

66
Q

what happens in primary succession once the pioneer species has changed the abiotic conditions?

A

conditions are less hostile, which means new organisms with different adaptations can move in and grow. these then die and decompose, adding more organic material, making the soil deeper and richer in minerals. larger plants like shrubs can start to grow in the deeper soil, which retains even more water

67
Q

what can happen when new species grow in primary succession?

A

new species may change the environment so that it becomes less suitable for the previous species

68
Q

how is secondary succession different to primary?

A

it happens in the same way, but because there’s already a soil layer succession starts at a later stage - the pioneer species in secondary succession are larger plants

69
Q

what happens at each stage of succession?

A

different plants and animals that are better adapted for the improved conditions move in, out-compete the plants and animals that are already there, and become the dominant species in the ecosystem

70
Q

how does succession cause biodiversity to increase?

A

the ecosystem becomes more complex. new species move in alongside existing species, so the variety of living organisms increases

71
Q

what is the final stage of succession?

A

the climax community - the ecosystem is supporting the largest and most complex community of plants and animals it can. it won’t change much more, it’s in a steady state

72
Q

what is an example of primary succession?

A

lichens grow on and break down rocks, releasing minerals
lichens die and are decomposed helping to form a thin soil, which thickens as more organic material is formed, mosses can grow
grasses ad flowering plants can move in, soil continues to deepen, as plants decompose
shrubs, ferns and small trees begin to grow, outcompeting others, becoming dominant species. diversity increases
soil deep and rich enough in nutrients to support large trees. climax community formed

73
Q

what is a climatic climax?

A

the climax community for a particular climate

74
Q

what is the climatic climax in a temperate climate?

A

there’s plenty of available water, milder temperatures and not much change between the seasons. the climatic climate will contain large trees because they can grow in these conditions once deep soils have developed

75
Q

what is the climatic climax in a polar climate?

A

there’s not much available water, temperatures are low and there’s massive changes between the seasons. large trees won’t ever be able to grow in these conditions, so the climatic climax contains only herbs or shrubs, but it’s still the climax community

76
Q

what is a plagioclimax?

A

the climax community when succession is stopped artificially by human activities

77
Q

what is an example of human activities preventing succession?

A

a regularly mown grassy field won’t develop shrubs and trees. the growing points of the woody plants are cut off by the lawnmower, so larger plants can’t establish themselves

78
Q

what is conservation?

A

the protection and management of species and habitats (ecosystems) in a suitable way

79
Q

how can land be preserved through halting succession?

A

e.g. large areas of moorland in Scotland that provide habitats for many species of plants and animals. if the moorland was left to natural processes, succession would lead to a climax community of spruce forest. this would mean the loss of the moorland habitat and could lead to the loss of some of the plants and animals that currently live there. preventing succession keeps the moorland ecosystem intact

80
Q

how can succession be managed to conserve the moorland ecosystem?

A

allow animals to graze on the land

light managed fires

81
Q

how can succession be managed by allowing animals to graze?

A

similar to mowing - the animals eat the growing points of the shrubs and trees, which stops them from establishing themselves and helps to keep vegetation low

82
Q

how can succession be managed by lighting managed fires?

A

after the fires, secondary succession will occur on the moorland - the pioneer species are the species that are being conserved, e.g. heather. larger species will take longer to grow back and will be removed again the next time the moor is burnt

83
Q

what does sustainable mean?

A

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

84
Q

what’s an example of finding a balance between human needs and conservation?

A

the Maasai Mara is a natural reserve in Kenya. it’s a savannah.
raising livestock can bring people into conflict with conservationists.
conservation trusts are working with the Maasai to help them make money from their land through conservation and ecotourism projects rather than farming, and to farm in a sustainable way. so the economic needs of the Maasai are met, while still allowing the area and its wildlife to be conserved

85
Q

what are some examples of conservation techniques?

A

plants can be conserved using seedbanks
fishing quotas
protected areas such as national parks and nature reserves
endangered species can be bred in captivity

86
Q

what are seedbanks?

A

stores of lots of seeds from lots of different plant species. if the plants become extinct in the wild, the stored seeds can be used to grow new plants

87
Q

what are fishing quotas?

A

limits to the amount of certain fish species that fishermen are allowed to catch. fishing quotas help to conserve fish species by reducing the numbers that are caught and killed

88
Q

how are protected areas a form of conservation technique?

A

they protect habitats (and so protect the species in them) by restricting urban development, industrial development and farming

89
Q

how is breeding endangered species in captivity a form of conservation technique?

A

it increases their numbers, then returns them to the wild

90
Q

what is the competitive exclusion principle?

A

2 species that use the same resource in the same way in the same space at the same time can’t co-exist
one will use the resources more effectively and eliminate the other

91
Q

what is the response to intraspecific competition?

A

animals - lower birth rate, higher mortality rate
invertebrates - slow down rate of growth and mature at a smaller size
plants - grow less well/ produce less seeds

92
Q

how can competitive exclusion be avoided?

A

the 2 species must diverge from each other over time in order for the 2 species to coexist

93
Q

what is a biome?

A

a major type of community e.g. tropical rainforest, desert

94
Q

what is a biosphere?

A

the entire portion of the earth inhabited by life. the sum of all ecosystems and communities

95
Q

what is an autotroph?

A

a producer - an organism that can trap an inorganic carbon source using energy from light or from chemicals

96
Q

what is crop rotation?

A

growing different crops in a field in successive years

97
Q

what is eutrophication?

A

an increase in the nitrates, phosphates or organic content of aquatic systems

98
Q

what is organic fertiliser?

A

a fertiliser containing organic substances such as urea, for example farmyard manure or mushroom compost

99
Q

what is a predator?

A

an animal that feeds by killing other organisms

100
Q

what is nitrogen fixation?

A

the conversion of gaseous nitrogen N2, into a more reactive form such as nitrate or ammonia

101
Q

what is a heterotroph?

A

an organism needing a supply of organic molecules as its carbon source

102
Q

what is inorganic fertiliser?

A

a fertiliser containing inorganic ions, such as nitrate, ammonium, potassium and phosphate ions

103
Q

what is organic farming?

A

farming without using synthetic chemicals as fertilisers

104
Q

why do we record the species living in a habitat?

A

it is necessary to estimate the population size to study how the distribution of the members of a population is influenced by biotic or abiotic factors

105
Q

what is random sampling?

A

using a quadrat, this is usually employed to eliminate bias. 2 numbered axis can be laid out over the sample area. generation of random numbers provides co-ordinates for areas to study

106
Q

what is systematic sampling?

A

transects, sometimes quadrats
samples are taken at regular intervals. more informative when a form of transition takes place. random sampling might miss this

107
Q

what are point quadrats?

A

a frame with vertical pins
every plant that touches the pins is recorded
useful if vegetation is dense

108
Q

what determines the size of a quadrat?

A

depends on size of species being investigated or what kind of groups or colonies the species live in

109
Q

what determines the number of samples being taken in the area?

A

the more samples you take in the habitat, the more reliable and representative the results will be

110
Q

how can species frequency data be measured?

A

how many quadrats contained the species you’re interested in out of the number of quadrats you used.
it gives a quick idea on general distribution, and is good when something is hard to count

111
Q

how can species density data be measured?

A

actually count number of species in each quadrat. average is estimated using the data collected

112
Q

what is the mark scheme for how to use a quadrat?

A

use a grid / split area into squares/ sections
method of obtaining random coordinates/ numbers
count numbers/ frequency of species in quadrat
calculate mean/ average number per quadrat
valid method of calculating total number of species

113
Q

what are the advantages of using a transect?

A

useful to monitor how communities change along an environment gradient
excellent for uneven terrain

114
Q

how is the snowshoe hair adapted?

A

greyish-brown fur turns white in winter for camouflage
large ears help in detecting predators
large furry feet act as snow shoes and protect the soles from cold
wide field of view to see predators approaching

115
Q

how is the lynx adapted?

A

excellent binocular vision for judging distances
warm thick furry coat protects from the cold
sharp teeth and claws for puncturing flesh
extra large paws act as snow shoes
very strong hind leg muscles capable of pouncing 6.5m

116
Q

primary succession mark scheme:

A

pioneer species
death and decomposition causes soil to build up ( a change in the abiotic environment) making environment less hostile
because of change, new species colonise, because of adaptations outcompeting previous species
this leads to increased biodiversity/ other factors mentioned in question
climax community develops

117
Q

what is soil?

A

broken bits of rock, organic matter (humus) and mineral ions (plant nutrition)

118
Q

how does succession occur in burnt heathland?

A

pioneer - mosses, lichens, fungi
stages - heather, bracken
gorse, tree sapling
climax community - oak, willow, beech, pine, birch

119
Q

how does succession occur in felled woodland?

A

pioneer - mosses, ferns, maybe lichens
stages - grasses, foxgloves
bramble, honeysuckle, tree sapling
climax community - oak, willow, beech, pine, birch

120
Q

how does succession occur in a drained pond?

A

pioneer - sphagnum mosses, reeds, rushes
stages - grasses, sedges
alder, willow, tree sapling
climax community - oak, willow, beech, pine, birch

121
Q

what is managed succession?

A

when animal or human behaviour prevents succession

122
Q

why might a particular habitat be conserved?

A

economic - earns money
aesthetic - beauty
ethical - maintenance of habitat for endangered species

A - Biology (21 decks)

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