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Biology Y13 > Populations and ecosystems > Flashcards

Populations and ecosystems Flashcards

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1
Q

what is an ecosystem?

A

an ecosystem is a group of interrelated organisms and their physical environment. Living and Non-living components interact

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2
Q

ecosystems consists of both..?

A

abiotic and biotic conditions

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3
Q

what are abiotic and biotic conditions?

A

Abiotic - non-living, physical features of an ecosystem (e.g temp, pH, light, soil conditions)
biotic - living features of an ecosystem (e.g presence of predators or food)

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4
Q

what is a habitat?

A

the place where an organism lives within the ecosystem

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5
Q

what is a microhabitat?

A

immediate surrounding (only for small organisms)

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6
Q

what is the environment?

A

set of conditions surrounding the habitat

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7
Q

what is a niche?

A

the role of the species within the habitat/ ecosystem. (e.g what it eats, predators, conditions it lives in, where and when it feeds etc)

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8
Q

a niche has biotic and abiotic interactions give examples?

A

biotic - the organism it eats, and those it’s eaten by
abiotic - the temperature range an organism can live, the time of day when an organism is active?

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9
Q

what is special about a niche?

A

each species has their own unique niche. it may look like they are both filling the same niche but there are slight variations

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10
Q

what happens if two species occupy the same niche?

A

they will compete with eachother. one species will be more successful than the other and only one species will remain

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11
Q

explain the difference between habitat and niche?

A

Habitat focuses on how the environment impacts the organism while niche focuses on how the organism impacts the environment.

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12
Q

what is a fundamental niche?

A

range of conditions in which an organism could survive

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13
Q

What is a realised niche?

A

Range of conditions in which it is actually found (usually more restricted because of competition)

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14
Q

what is an adaption?

A

an adaption is a feature that members of a species have that increases their chance of survival and reproduction.

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15
Q

what are the three types of adaptions?

A

physiological, behavioural, anatomical

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16
Q

what advantage do giraffe’s have ?

A

long necks, so when food is scarce they are at an advantage

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17
Q

what is natural selection?

A

process by which organisms with better adaptions are more likely to survive, reproduce and pass on advantageous alleles that determine these adaptions. this increases the frequency of these alleles in the population, which means the adaption becomes more common.

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18
Q

what else do organisms need to adapt to?

A

abiotic and biotic conditions

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19
Q

how are otters adapted to abiotic conditions?

A

otters have webbed feet, this increases their chances of survival they can live and hut on both land and water

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20
Q

how are some bacteria adapted to biotic conditions?

A

some bacteria produce antibiotic - increases chance of survival as it kills other species of bacteria in the same area

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21
Q

variation in population size

A
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22
Q

what is a population?

A

group of organisms of the same species living in a habitat at the same time. (e.g all foxes in the woods)

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23
Q

what is a community?

A

all individuals of different species living in the same place at the same time. (e.g all foxes, squirrels, trees form a community)

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24
Q

what is the population size?

A

is the total number of organisms of one species in a habitat

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25
Q

what is the carrying capacity?

A

the maximum stable population size of a species that an ecosystem can support is called the carrying capacity

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26
Q

why does carrying capacity vary?

A

as a result of change in abiotic and biotic factors

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27
Q

when abiotic conditions are ideal what is more likely to happen?

A

species, organisms can grow more quickly and reproduce successfully

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28
Q

give an example of this?

A

when the temperature a mammal’s surroundings is the ideal temperature for metabolic reactions to take place, they don’t have to use up as much energy maintaining their body temperature. this means more energy can be used for growth and reproduction, so the population will increase in size.

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29
Q

when abiotic factors are not ideal, what is likely to happen?
give an example?

A

organisms can’y grow or reproduce successfully.
e.g when the temperature of a mammal’s surroundings is significantly lower or higher than their optimum body temperature, they have to use a lot of energy to maintain the right body temperature. this means less energy will be available for growth and reproduction, so population size will decrease

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30
Q

what is competition?

A

where two or more organisms try to use the same resources that is insufficient to satisfy all requirements fully. it may be interspecific or intraspecific.

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31
Q

what is interspecific competition?

A

interspecific competition is where organisms of different species compete with each other for the same resources. these species usually occupy the same niche and one of them has an competitive advantage.

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32
Q

what will usually happen?

A

population of this species gradually increase in size, other decrease. if conditions remain the same, will lead to complete removal of the other species. A.K.A competitive exclusion principle

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33
Q

what is the competitive exclusion principle?

A

where 2 species competing for limited resources, one uses resources more effectively, ultimately eliminating the other

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34
Q

in order for interspecific competition to affect population size what must be affected? give an example.

A

birth or death rate
e.g increased food supply does not necessarily mean more individuals but bigger individuals
e.g decrease in food = death by starvation, population decreases
e.g increase food supply, more individuals survive and pass on alleles, so population increases

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35
Q

What is intraspecific competition?

A

intraspecific competition occurs when individuals of the same species compete with one another for the same resources. it is the availability of resources that determines the population size. it can cause a cyclical change in population size around the ecosystem’s carrying capacity.

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36
Q

why does the population size change around the carrying capacity?

A

this is because the population of species increases when resources are plentiful.

37
Q

as population increases, more organisms will be competing for the same amount of food and space. Eventually these resources become limited. now what happens if the population grows beyond the carrying capacity?

A

if organisms grow beyond the carrying capacity, there won’t be enough resources for all organisms and the population will begin to decline

38
Q

how does the cycle continue?
if there is a smaller population..?

A

there’s less competition for space and food, which is better for growth and reproduction - so the population starts to grow again. this cyclical pattern then continues

39
Q

give an example of Intraspecific competition? also draw a graph to show this.

A
  • lots of resources for rabbits
  • population grew so large that resources became limited - the carrying capacity of the ecosystem was exceeded. as there weren’t enough resources, the rabbit population fell
  • a smaller population of rabbits (below the carrying capacity) meant there was less competition, so population of the rabbits began to grow again
40
Q

predation

A
41
Q

what is predation?

A

is where an organism (the predator) kills and eats another organism (the prey)
e.g lions kill and eat (predate on) buffalo. the population of predators and prey’s are interlinked. as population of one changes, it causes the other to change.

42
Q

explain what happens if the prey population increases?

A

then there is more food for predators, so the predator population grows.

43
Q

what happens when predator population increases?
what does this mean

A

as predator population increases, more prey is eaten so the prey population then begins to fall.
this means there’s less food for the predators, so their population decreases, and so on.

44
Q

draw a graph to predation

A
45
Q

What series of patterns does a predator-prey graph show?

A
  • the size of the predator and prey both fluctuate
  • there will always be more prey than predators - so the prey population will always peak at a higher point
  • the size of the population will always change in the prey and then the predator (lag time)
46
Q

Sampling

A
47
Q

How to sample plant species over a large area?

A

 obtain a map of the area
 divide the map into grids
 select a large number of coordinates using a running mean
 select a random set of coordinates using a random number chart
 in each coordinate place a quadrat
 measure abundance of the plant species in each quadrat = frequency or percentage cover
 calculate average for the whole area

48
Q

How to sample plants species along a path?

A

 use a transect
 place a tape along the path, count number of plants touching tape (Line Transect)
 or
 place a tape along the path, at regular intervals along the tape place a quadrat, measure abundance within the quadrat (Belt Transect)

49
Q

How to sample animal species in an area?

A

 mark-release-recapture technique
 set a trap
 capture the animal species [Sample 1]
 mark them, tag or fluorescent marker – ensure its non-toxic and not harmful
 release them
 after some time - sufficient time for them to mix with the whole population, replace the trap
 count number in 2nd set [Sample 2] and count the number marked
 estimate population size by: number in sample 1 x number in sample 2 /
marked in sample 2

50
Q

Mark-Release-Recapture

A
51
Q

What is the equation for Mark-Release-recapture to calculate the population number?

A

Population = Total number of first sample(marked) X total number in the second sample / total number of marked individuals required

52
Q

Assumptions of Mark-release-recapture technique?

A

 no births or deaths
 no immigration or emigration
 marked animals mix evenly with population
 mark is not toxic
 mark does not come off
 large population

53
Q

Ecological succession

A
54
Q

what is succession?

A

change in the ecological community over time

55
Q

what is primary succession?

A

when a pioneer species colonise land which has never had any vegetation on it over a long period of time to form a climax community. (pioneer species such as lichen can colonise bare rock)

56
Q

Describe the process of succession - MSA!

A
  1. (Colonisation by) pioneer species;
  2. Pioneers/species/organisms change the
    environment/habitat/conditions/factors;
    Accept example of change e.g. forms soil/humus/organic matter/nutrients.
    Must convey idea of change being caused by pioneers/species/organisms
  3. (Environment becomes) more suitable for other/new species
    OR
    (Environment becomes) less suitable for previous species;
    Accept previous species out-competed.
  4. Change/increase in diversity/biodiversity;
    1. (To) climax community;
57
Q

What are pioneer species?

A

first species to colonise

58
Q

What may result in the formation of bare rock?

A

natural disasters such as: earthquakes and volcanic eruption

59
Q

What is lichen?

A

Lichen is green, white grey looking patches found on bare rock. lichen is also an example of a symbiotic relationship of two species coexisting together and bringing a mutual benefit. it consists of algae and fungus.

60
Q

explain the role of algae within lichen which explain why lichen is able to survive on bare rock?

A

Algae can photosynthesise which explain why lichen is green. and because it is photosynthesising it is creating glucose and carbohydrates for storage and sharing it with the fungi

61
Q

fungi has two advantages when it comes to adapting to harsh abiotic conditions?

A

can absorb water a bit like a sponge, so when it rains it can absorb and hold onto that water. whereas the rest of the water is going to run off the rocks

62
Q

explain how lichen a pioneer species is able to change the harsh abiotic factors?

A

through it’s death and decomposition and change abiotic factors to become less harsh and form a thin layer of soil called humus.

63
Q

What does soil/ Humus allow for?

A

this means mosses and smaller plant seeds can lodge into that thin layer and soil and will retain some water and minerals so these plants can now grow and reproduce

64
Q

explain the effect this has on the soil?

A

it will increase the depth and nutrient content of the soil, so we now have thicker soil with even more nutrients, so can now hold a larger amount of water, so even larger plants are able to grow and reproduce

65
Q

What is the second advantage of fungi when it comes to surviving on bare rock?

A

can release enzymes to outside of it’s cells (extracellular) and releases these enzymes onto the rock to release minerals. this can be absorbed by the algae and the fungi?

66
Q

so the lichen is helpful to survival when..?

A

there is little water available, no food source other than light and no minerals (except in rock) and no competition with species

67
Q

How does bare rock change abiotic factors to become less harsh?

A

overtime lichen will die and decay, but reproduce so constantly have more lichen as they die. When they die and reproduce a thin layer of soil is formed, Humus

68
Q

Why will existing species get outcompeted by new species constantly?
Give an example

A

overtime each new species changes the environment. in such a way that it becomes less suitable for the previous species. therefore each existing species is outcompeted by a new species colonising.

e.g when a new plant starts to grow, they will be covering up the lichen, so can no longer receive sunlight –> outcompeted

69
Q

what is the final step?

A

climax community

70
Q

what is a climax community?

A

the endpoint of succession: the community is now in equilibrium with the environment

71
Q

what is the climax community dominated by?

A

by trees

72
Q

in the end we end up getting..?

A

and increased biodiversity, abiotic factors are now more favourable and the environment becomes more stable

73
Q

And when the environment is more stable, the environment can support..?

A

a whole range of different species and animals, so increased survival of species

74
Q

What is Secondary succession?

A

Occurs on ground which had been previously colonised but is now available because the community has now been destroyed. (so soil is already created)

75
Q

what are some causes of disruption?

A

human destruction e.g deforestation
or grazing by animals and natural disasters such as floods

76
Q

What happens if succession starts on bare sand

A

the abiotic factors will be different, for example a high salt concentration from the ocean and there will be very little water availability because sand is porous, so water will seep through sand. Also pioneer species will be different on a sand dune, instead of lichen there will be xerophytes.

77
Q

why will the whole area recover if a plant gets destroyed?

A

because there will be so many different species and individuals so whole area start to recover

78
Q

when there are more individuals of different species in the same are we get..?

A

more complex food webs

79
Q

Conservation of habitats

A
80
Q

what is the conservation of habitats?

A

Conservation is the protection and management of species and habitats (i.e. ecosystems) in a sustainable way.

the prevention of succession progressing through conservation .

81
Q

What is the main biggest cause of destruction to habitats?

A

Humans -

82
Q

what affect does human destruction have on habitats?

A

loss of food and space for organisms which leads to extinction

83
Q

so to conserve habitats we need to?

A

manage succession

84
Q

when does destruction usually happen?

A

as human population grows, there is more need for food and space (housing), timber can be used for resources in housing. (the need for natural resources also increases)

85
Q

what does maintaining succession do?

A

prevents climax community, so a greater variety of habitats are conserved and therefore a greater variety of habitats are conserved, and therefore a greater range of species

86
Q

But we need to compromise the conflict between human needs and conservation. how is this done?

A

For example, forests can be coppiced to provide timber for fuel and furniture, which still allows for species to survive but there is also a lot of space/ area for a whole range of species to thrive.

87
Q

What is coppicing?

A

where trees are cut down to the base.

88
Q

Explain the advantage of conserving rainforests? - MSA

A
  1. Conserve/protect
    species/plants/animals/organisms
    OR
    For (bio)diversity;
  2. Conserve/protect habitats/niches
    OR
    Provides/many habitats/niches;
  3. Reduces climate change;
  4. Source of medicines/drugs/wood;
  5. Reduces erosion/eutrophication;
  6. (For) tourism;
89
Q

FINISH

A

Biology Y13 (13 decks)

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